Cheetah SPI Host Adapter User Manual v3.08
Contents
1. The default behavior of locating the Cheetah DLL is dependent on the operating system platform and specific programming language environment For example for a C or C application the following rules apply On a Windows system this is as follows 1 2 3 The directory from which the application binary was loaded The applications current directory 32 bit system directory for a 32 bit application Examples o c Windows System32 Windows XP Vista 7 32 bit o C Windows System64 Windows XP 64 bit o Windows SysWow64 Windows Vista 7 64 bit 64 bit system directory for a 64 bit application Examples o C Windows System32 Windows XP Vista 7 64 bit The Windows directory Ex c Windows The directories listed in the PATH environment variable On a Linux system this is as follows First search for the shared object in the application binary path If the proc filesystem is not present this step is skipped Next search in the applications current working directory Search the paths explicitly specified in LD_LIBRARY_PATH Finally check any system library paths as specified in etc ld so conf and cached in etc ld so cache On a Mac OS X system this is as follows ile 2 3 First search for the shared object in the application binary path Next search in the applications current working directory Search the paths explicitly specified in DYLD_LIBRARY_PATH 17 Na amp2. Therefore this function may be called repeatedly if the same sequence of commands is to be shifted across the bus multiple times As data is shifted by the Cheetah device onto the MOSI line the slave device will shift the same amount of data back across the MISO line This function will put the first num_bytes number of bytes received from the slave device into the data_in 41 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual array To ensure that all of the data from the slave device is captured call ch_ spi batch length to determine how much data to expect from the slave device Setting num_ bytes to 0 is permissible for cases where the data from slave device is not reguired and can simply be discarded If the number of bytes received from the slave device is less than num_ bytes only the number of bytes received will be put into data_in However all of the outgoing bytes in the queue will still be shifted When setting num_bytes to a value less than the total outgoing length a special optimization will automatically take effect This optimization will help reduce the traffic on the USB bus in the inbound direction Cheetah to host This optimization introduces an 8 clock cycle delay in the operation of the Cheetah device at the point that the Cheetah device stops sending the slave response back to the host Submit an Asynchronous SPI Shift ch_spi_async_submit int ch spi async submit Cheetah cheetah Submit the SPI s
3. devices are ordinarily specified to accept logic high inputs above approximately 3 volts 2 2 2 ESD protection The Cheetah adapter has built in electrostatic discharge protection to prevent damage to the unit from high voltage static electricity This adds a small amount of parasitic capacitance approximately 15 pF to the SPI bus Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 2 2 3 Power Consumption The Cheetah adapter consumes approximately 125 mA of power from the host PC However it reports itself to the host PC as a low power device This reporting allows the Cheetah adapter to be used when its host port is connected to a bus powered hub which are only technically specified to supply 100 mA per port Normally this extra amount of power consumption should not cause any serious problems since other ports on the hub are most likely not using their own 100 mA budget If there are any concerns regarding the total amount of available current supply it is advisable to plug the Cheetah adapter directly into the host PC s USB host port or to use a self powered hub 2 3 USB 2 0 The Cheetah adapter is a High Speed USB 2 0 device It can be plugged into either a high speed or full speed port However a high speed port must be used to achieve full throughput at high data rates SPI clock rates gt 3 Mbps 2 4 Temperature Specifications The Cheetah adapter is designed to be operated at room temperature 10 35 C The electro
4. 1 3 5 1 Detecting Ports As described in following API documentation chapter the ch_find devices routine can be used to determine the mapping between the physical Cheetah adapter and their port numbers 3 6 Cheetah Dynamically Linked Library 3 6 1 DLL Philosophy The Cheetah DLL provides a robust approach to allow present day Cheetah enabled applications to interoperate with future versions of the device interface software without recompilation For example take the case of a graphical application that is written to communicate SPI through a Cheetah device At the time the program is built the Cheetah software is released as version 1 2 The Cheetah interface software may be improved many months later resulting in increased performance and or reliability it is now released as version 1 3 The original application need not be altered or recompiled The user can simply replace the old Cheetah DLL with the newer one How does this work The application contains only a stub which in turn dynamically loads the DLL on the first invocation of any Cheetah API function If the DLL is replaced the application simply loads the new one thereby utilizing all of the improvements present in the replaced DLL On Linux the DLL is technically known as a shared object SO 16 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 3 6 2 DLL Location Total Phase provides language bindings that can be integrated into any custom application
5. Adapter User Manual polarity the polarity of the clock signal see Table 4 phase the phase of the clock signal to sample on see Table 5 bitorder the bit order big endian or little endian see Table 6 ss polarity the polarity of the slave select signals Table 4 polarity enumerated types CH SPI POL RISING FALLING Clock idle low active high CH SPI POL FALLING RISING Clock idle high active low Table 5 phase enumerated types CH SPI PHASE SAMPLE SETUP Sample on the leading edge of the clock signal CH SPI PHASE SETUP SAMPLE Sample on the trailing edge of the clock signal Table 6 bitorder enumerated types CH SPI BITORDER MSB Big endian bit order CH SPI BITORDER_ LSB Little endian bit order Return Value A Cheetah status code is returned with CH_OK on success Specific Error Codes None Details These configuration parameters specify how to clock the bits that are sent and received on the Cheetah SPI interface The polarity option specifies which transition constitutes the leading edge and which transition is the falling edge For example CH SPI POL RISING FALLING would configure the SPI to idle the SCLK clock line low The clock would then transition low to high on the leading edge and high to low on the trailing edge The phase option determines whether to sample or setup on the leading edge of the clock signal For example CH SPI PHASE SAMPLE SETUP would configure the SPI to sample
6. Host Interface Speed ch_host ifce_speed int ch host ifce speed Cheetah cheetah Return the interface host speed Arguments cheetah handle of a Cheetah adapter Return Value This function returns enumerated values specifying the USB speed at which the host computer is communicating with the given Cheetah device See Table 3 Table 3 Host interface speed enumerated types CH HOST IFCE FULL SPEED Full speed 12 Mbps interface CH HOST IFCE HIGH SPEED High Speed 480 Mbps interface Specific Error Codes 31 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual None Details Used to determine the USB communication rate between the Cheetah device and the host A High Speed USB interface is highly recommended to take full advantage of the high speed SPI interface 5 5 SPI Interface 5 5 1 SPI Overview In order to use the Cheetah API to send SPI data across the bus at high speed commands are accumulated in a queue until a call is made to batch shift all of the queued commands The sequence of commands in the command queue for a typical SPI transaction is 1 Call ch_ spi queue clear to clear the command queue 2 Call ch _spi queue oe to add a command to the queue to enable the Cheetah devices outputs on the SPI bus 3 Call ch spi queue ss to add a command to the queue to enable the slave select signal 4 Callch spi queue byte and ch spi queue array to queue data to be sent across the SP
7. indirect special general incidental or consequential damages arising from the use of its site the software or documentation downloaded from its site or any derivative works thereof even if Total Phase or distributors have been advised of the possibility of such damage The software its documentation and any derivative works is provided on an as is basis and thus comes with absolutely no warranty either express or implied This disclaimer includes but is not limited to implied warranties of merchantability fitness for any particular purpose and non infringement Total Phase and distributors have no obligation to provide maintenance support or updates Information in this document is subject to change without notice and should not be construed as a commitment by Total Phase While the information contained herein is believed to be accurate Total Phase assumes no responsibility for any errors and or omissions that may appear in this document 6 2 Life Support Equipment Policy Total Phase products are not authorized for use in life support devices or systems Life support devices or systems include but are not limited to surgical implants medical systems and other safety critical systems in which failure of a Total Phase product could cause personal injury or loss of life Should a Total Phase product be used in such an unauthorized manner Buyer agrees to indemnify and hold harmless Total Phase its officers employees affiliate
8. on the leading edge and setup on the trailing edge of the clock 35 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual For example mode 3 in the figure found in the SPI Background chapter would correspond to the pair CH SPI POL FALLING RISING CH SPI PHASE SETUP SAMPLE The bitorder option is used to indicate whether LSB or MSB is shifted first The ss_polarity option is a bit mask that indicates whether each SS line is active high or active low For example setting ss_polarity to 0x05 would mean that SS3 and SS1 are active high and SS2 is active low Clear Batch Gueue ch_spi_gueue clear int ch spi queue clear Cheetah cheetah Clear the batch gueue Arguments cheetah handle of a Cheetah adapter Return Value A Cheetah status code is returned with CH_OK on success Specific Error Codes None Details All queued data and commands are removed from the queue Queue the Cheetah Output Enable ch_spi_queue_oe int ch spi queue oe Cheetah cheetah u08 oe Enable disable the outputs Arguments cheetah handle of a Cheetah adapter oe 0 to disable the outputs and 1 to enable Return Value A Cheetah status code is returned with CH_OK on success 36 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual Specific Error Codes None Details This function enables and disables the outputs on the Cheetah device When enabled the Cheetah device connects to the SPI bus and is ready to drive th
9. the DLL and API integration of the Cheetah software Furthermore all API calls can potentially return the errors CH UNABLE_TO_ LOAD DRIVER or CH INCOMPATIBLE DRIVER If either of these errors are seen please make sure the driver is installed and of the correct version Where appropriate compare the language binding versions e g CH HEADER VERSION found in cheetah h and CH CFILE VERSION found in cheetah c to verify that there are no mismatches Next ensure that the Rosetta language binding e g cheetah c and cheetah h are from the same release as the Cheetah DLL If all of these versions are synchronized and there are still problems please contact Total Phase support for assistance Note that any API function that accepts a Cheetah handle can potentially return the error code CH INVALID HANDLE if the handle does not correspond to a valid Cheetah device that has already been opened If this error is received check the application code to ensure that the ch_open 22 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual command returned a valid handle and that this handle was not corrupted before being passed to the offending API function Finally any API call that communicates with a Cheetah device can also return the error CH COMMUNICATION ERROR This means that while the Cheetah handle is valid and the communication channel is open there was an error communicating with the device This is possible if the device was unp
10. via hardware control This SS is in the same location as the SS line of the Aardvark and Beagle products SS2 Pin 1 Second Slave Select an additional control line that allows slaves to be turned on and off via hardware control SS2 Pin 3 Third Slave Select an additional control line that allows slaves to be turned on and off via hardware control 2 1 5 Powering Downstream Devices It is possible to power a downstream target such as an SPI EEPROM with the Cheetah adapter s power which is provided by the USB bus It is ideal if the downstream device does not consume more than 20 30 mA The Cheetah adapter is compatible with USB hubs as well as USB host controllers Bus powered USB hubs are technically only rated to provide 100 mA per USB device If the Cheetah adapter is directly plugged into a USB host controller or a self powered USB hub it can theoretically draw up to 500 mA total leaving approximately 375 mA for any downstream target However the Cheetah adapter always reports itself to the host as a low power device Therefore drawing large amounts of current from the host is not advisable 2 2 Signal Specifications Power Consumption 2 2 1 Logic High Levels All signal levels should be nominally 3 3 volts 10 logic high This allows the Cheetah adapter to be used with both TTL 5 volt and CMOS logic level 3 3 volt devices A logic high of 3 3 volts will be adequate for TTL compliant devices since such
11. Cheetah SPI Host Adapter ry Features P H A S E SPI Master Full Duplex SPI at 40 MHz Unsupported Overclocking up to 50 MHz All Modes Supported e High Speed USB Device 480 Mbps transfer to host PC Actual Host Data Throughput Nearly 100 of SPI Clock Rate Windows Linux and Mac OS X compatible Supported products Cretan TT Low cost Cheetah SPI Host Adapter User Manual v3 08 February 28 2014 Summary The Cheetah SPI Host Adapter is a high speed SPI shifter that is capable of communicating over an SPI serial bus at up to 50 MHz 6 TOTAL PHASE Cheetah SPI Host Adapter User Manual 1 General Overview 1 1 SPI Background 1 1 1 SPI History SPI is a serial communication bus developed by Motorola It is a full duplex protocol which functions on a master slave paradigm that is ideally suited to data streaming applications 1 1 2 SPI Theory of Operation SPI requires four signals clock SCLK master output slave input MOSI master input slave output MISO and slave select SS Figure 1 Sample SPI Implementation Each slave device requires a separate slave select signal SS This means that as devices are added the circuit increases in complexity Three signals are shared by all devices on the SPI bus SCLK MOSI and MISO SCLK is generated by the master device and is used for synchronization MOSI and MISO are the data lines The direction of transfer is indicated by their names Data i
12. I bus 5 Call ch spi queue ss to queue a command to disable the slave select signal 6 Optionally call ch spi queue oe to queue a command to disable the outputs of the Cheetah device 7 Call ch_spi_batch_ shift to send the accumulated accumulated commands across the SPI bus Please note that the queue is not cleared after it has been executed This allows the same queue to be executed multiple times without re queuing commands The only way to clear a queue is by calling ch spi queue clear If the user wishes to repeat the exact same shift sequence on the bus the last step can be executed without the preceding ones Also the OE enable commands and SS assert deassert commands are held persistent on the Cheetah device For example if the SS line is left asserted after one transaction it will stay asserted until modified in a subsequent transaction 32 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual The data sent from the slave device to the Cheetah device across the MISO line will be filled into the data_in parameter of the ch_spi_batch_ shift function Also ch spi batch length can be called prior to calling ch spi batch shift to find out how large of an array needs to be allocated for the data_in argument The SPI master and slave must both be configured to use the same bit protocol mode Prior to sending any data across the SPI bus the application should call ch spi configure and ch spi bitrate to set the pr
13. TOTAL PHASE Cheetah SPI Host Adapter User Manual 4 Finally check the usr lib and usr local lib system library paths If the DLL is still not found the CH UNABLE TO LOAD LIBRARY error will be returned by the binding function 3 6 3 DLL Versioning The Cheetah DLL checks to ensure that the firmware of a given Cheetah device is compatible Each DLL revision is tagged as being compatible with firmware revisions greater than or egual to a certain version number Likewise each firmware version is tagged as being compatible with DLL revisions greater than or egual to a specific version number Here is an example DLL v1 20 compatible with Firmware gt v1 15 Firmware v1 30 compatible with DLL gt v1 20 Hence the DLL is not compatible with any firmware less than version 1 15 and the firmware is not compatible with any DLL less than version 1 20 In this example the version number constraints are satisfied and the DLL can safely connect to the target firmware without error If there is a version mismatch the API calls to open the device will fail See the API documentation for further details 3 7 Rosetta Language Bindings API Integration into Custom Applications 3 7 1 Overview The Cheetah Rosetta language bindings make integration of the Cheetah API into custom applications simple Accessing Cheetah functionality simply reguires function calls to the Cheetah API This API is easy to understand much like the ANSI C library
14. aving the other 4 batches still outstanding The function will fill the user supplied buffer with the incoming MISO data for the completed batch The incoming data will be copied from the internal incoming buffer originally created by ch_spi_async_submit into the user supplied data in buffer The internal buffers both outgoing and incoming for the completed batch will be deleted before this function returns to the application If ch_close is called without collecting pending asynchronous batches those batches will be canceled even if they are in progress All temporary buffers will be freed as well 44 amp TOTAL PHASE Cheetah SPI Host Adapter User Manual A suggested mode of operation would be as follows 1 Submit 2 4 asynchronous batches each with about 40 ms worth of SPI shifting A single batch can contain many SPI commands packets of course 2 Call ch_spi async collect to collect one batch Signal another thread to process this data 3 Submit another asynchronous batch to replace the one that was just collected 4 Repeat steps 2 amp 3 while your other thread simply processes the data Note that this merely is a recommendation for use and developers can modify this procedure as it suits their own application requirements The application must keep full accounting of how many batches have been submitted and how many are collected during each step of the process It is even possible that the application will
15. ber Specific Error Codes None Details None Get Unique ID ch_unique_id u32 ch unique id Cheetah cheetah Return the unique ID of the given Cheetah device Arguments 28 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual cheetah handle of a Cheetah adapter Return Value This function returns the unique ID for this Cheetah adapter The IDs are guaranteed to be non zero if valid The ID is the unsigned integer representation of the 10 digit serial number Specific Error Codes None Details None Status String ch_status_ string const char ch status string int status Return the status string for the given status code Arguments status status code returned by a Cheetah API function Return Value This function returns a human readable string that corresponds to status If the code is not valid it returns a NULL string Specific Error Codes None Details None Version ch_version int ch version Cheetah cheetah CheetahVersion version Return the version matrix for the device attached to the given handle Arguments cheetah handle of a Cheetah adapter 29 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual version pointer to pre allocated structure Return Value A Cheetah status code is returned with CH_OK on success Specific Error Codes None Details If the handle is 0 or invalid only the software version is set See the details of ch_open_ext
16. bit and 64 bit distributions of Linux with kernel 2 6 and integrated USB support When using the 32 bit library on a 64 bit distribution the appropriate 32 bit system libraries are also required 3 1 4 Mac OS X Compatibility The Cheetah software is compatible with Intel versions of Mac OS X 10 5 Leopard 10 6 Snow Leopard 10 7 Lion 10 8 Mountain Lion and 10 9 Mavericks Installation of the latest available update is recommended 3 2 Windows USB Driver 3 2 1 Driver Installation To install the appropriate USB communication driver under Windows use the Total Phase USB Driver Installer before plugging in any device The driver installer can be found either on the CD ROM use the HTML based guide that is opened when the CD is first loaded to locate the Windows installer or in the Downloads section of the Cheetah adapter product page on the Total Phase website After the driver has been installed plugging in a Cheetah adapter for the first time will cause the adapter to be installed and associated with the correct driver The following 12 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual steps describe the feedback the user should receive from Windows after a Cheetah adapter is plugged into a system for the first time Windows XP 1 The Found New Hardware notification bubble will pop up from the system tray and state that the Total Phase Cheetah Host Adapter has been detected Note that installation may take a whi
17. e signal lines When the Cheetah output enable is disabled the device disconnects from the bus and each signal line is held at their current values with very weak internal pull up or pull down on the Cheetah device Call this function to enable the Cheetah outputs before calling any of the other queue functions Queue Slave Select Signals ch_spi_queue_ss int ch spi queue ss Cheetah cheetah u08 active Queue Slave Select assertion deassertion Arguments cheetah handle of a Cheetah adapter active a bit mask based on the 3 SS lines where 1 corresponds to assertion and 0 to deassertion Return Value A Cheetah status code is returned with CH_OK on success Specific Error Codes None Details This function adds a command to the batch queue to assert deassert the SPI slave select lines The active parameter is a bit mask For example setting active to 0x05 would mean that SS3 and SS1 are asserted and SS2 is deasserted The polarity of the slave select is determined from a previous call to ch spi configure Queue a Byte ch_spi_queue_byte int ch spi queue byte Cheetah cheetah 37 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual int count u08 data_out Queue a byte value to be sent across the bus one or more times Arguments cheetah handle of a Cheetah adapter count number of bytes to put in queue data_out value of the byte to queue Return Value Returns the actual number of times the byt
18. e connector If you flip your Cheetah adapter over Figure 4 such that the text on the serial number label is in the proper upright position the pin order is as shown in the following diagram Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual Figure 4 The Cheetah SPI Host Adapter in the upside down position Pin 1 is located in the lower left corner of the connector and Pin 10 is located in the upper right corner of the connector 2 1 2 Order of Leads 1 SS2 2 GND SS3 NC 5V MISO NC 5V SCLK MOSI SS1 of E a a le Ue _ GND 2 1 3 Ground GND Pin 2 GND Pin 10 It is imperative that the Cheetah adapter s ground lead is connected to the ground of the target system Without a common ground between the two the signaling will be unpredictable and communication will likely be corrupted Two ground pins are provided to ensure a secure ground path 2 1 4 SPI Pins SCLK Pin 7 Serial Clock control line that is driven by the master and regulates the flow of the data bits MOSI Pin 8 Master Out Slave In this data line supplies output data from the master which is shifted into the slave Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual MISO Pin 5 Master In Slave Out this data line supplies the output data from the slave to the input of the master SS1 Pin 9 Primary Slave Select the primary control line that allows slaves to be turned on and off
19. e in data_ out was added to the queue This should equal count Specific Error Codes None Details Queues count number of bytes to send and sets each byte to the value of data_out For this command and the ch_spi_queue_array command the polarity phase and bit ordering will be determined by the configuration set with the ch spi configure function Gueue a Byte Array ch_spi_gueue array int ch spi queue array Cheetah cheetah ul6 num bytes const u08 data out Gueue an array of bytes to be sent across the bus Arguments cheetah handle of a Cheetah adapter num bytes number of bytes in data_out data out byte array to gueue Return Value Returns the number of bytes queued This should equal num bytes 38 SJ amp TOTAL PHASE Cheetah SPI Host Adapter User Manual Specific Error Codes None Details The array will be processed with a minimal run length encoding algorithm so repeated sequences of single bytes will be sent more efficiently This helps reduce outgoing host to Cheetah bandwidth on the USB bus For this command and the ch_spi_ queue byte command the polarity phase and bit ordering will be determined by the configuration set with the ch_ spi _ configure function Queue a Delay in Cycles ch_spi_queue_delay_cycles int ch spi queue delay cycles Cheetah cheetah int cycles Oueue a delay value on the bus in units of clock cycles Arguments cheetah handle of a Cheetah adapter cyc
20. for the definition of CheetahVersion Sleep ch_sleep_ms u32 ch_sleep ms u32 milliseconds Sleep for given amount of time Arguments milliseconds number of milliseconds to sleep Return Value This function returns the number of milliseconds slept Specific Error Codes None Details This function provides a convenient cross platform function to sleep the current thread using standard operating system functions The accuracy of this function depends on the operating system scheduler This function will return the number of milliseconds that were actually slept Target Power ch_target_power int ch target power Cheetah cheetah u08 power mask Activate deactivate target power pins 4 and 6 30 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual Arguments cheetah handle of a Cheetah adapter power mask enumerated values specifying power pin state See Table 2 Table 2 power mask enumerated types CH TARGET POWER OFF Disable target power pins CH TARGET POWER ON Enable target power pins CH TARGET POWER QUERY Queries the target power pin state Return Value The current state of the target power pins on the Cheetah adapter will be returned The configuration will be described by the same values as in the table above Specific Error Codes None Details Both target power pins are controlled together Independent control is not supported This function may be executed in any operation mode
21. functions e g there is no unnecessary entanglement with the Windows messaging subsystem like development kits for some other embedded tools First choose the Rosetta bindings appropriate for the programming language Different Rosetta bindings are included with the software distribution on the distribution CD They can also be found in the software download package available on the Total Phase website Currently the following languages are supported C C Python Visual Basic 6 Visual Basic NET and Ci Next follow the instructions for each language binding on how to integrate the bindings with your application build setup As an example the integration for the C language bindings is described below For information on how to integrate the bindings for other 18 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual languages please see the example code included on the distribution CD and also available for download on the Total Phase website 1 Include the cheetah h file included with the API software package in any C or C source module The module may now use any Cheetah API call listed in cheetah h 2 Compile and link cheetah c with your application Ensure that the include path for compilation also lists the directory in which cheetah h is located if the two files are not placed in the same directory 3 Place the Cheetah DLL included with the API software package in the same directory as the applicatio
22. ge Remove 13 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 3 Follow the instructions in the uninstaller Windows Vista 7 1 Select Control Panel Uninstall a program 2 Right click on Total Phase USB Driver and select Uninstall Change 3 Follow the instructions in the uninstaller 3 3 Linux USB Driver As of version 3 08 the Cheetah communications layer under Linux no longer requires a specific kernel mode or user mode driver to operate This differs from previous versions that required the user to ensure independently that the libusb library was installed on the system See the README txt in the API package for more details Most modern Linux distributions use the udev subsystem to help manipulate the permissions of various system devices This is the preferred way to support access to the Cheetah adapter such that the device is accessible by all of the users on the system upon device plug in For legacy systems there are two different ways to access the Cheetah adapter through USB hotplug or by mounting the entire USB filesystem as world writable Both require that proc bus usb is mounted on the system which is the case on most standard distributions 3 3 1 UDEV Support for udev requires a single configuration file that is available on the software CD and also listed on the Total Phase website for download This file is 99 totalphase rules Please follow the following steps to enable the appr
23. h the hardware version or vice versa The version information will be available in the memory pointed to by ch_ ext Details If 0 is passed as the pointer to the structure ch_ ext this function will behave exactly like ch_open The CheetahExt structure is described below struct CheetahExt CheetahVersion version Features of this device int features The CheetahVersion structure describes the various version dependencies of Cheetah components It can be used to determine which component caused an incompatibility error struct CheetahVersion Software and hardware versions ul6 software ul6 firmware ul6 hardware Hardware revisions that are compatible with this software version The top 16 bits gives the maximum accepted hardware revision The lower 16 bits gives the minimum accepted hardware revision 26 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual u32 hw revs for sw Firmware revisions that are compatible with this software version The top 16 bits gives the maximum accepted firmware revision The lower 16 bits gives the minimum accepted firmware revision u32 fw revs for sw Driver revisions that are compatible with this software version The top 16 bits gives the maximum accepted driver revision The lower 16 bits gives the minimum accepted driver revision This version checking is currently only pertinent for WIN32 platfor
24. hift operations in the gueue for asynchronous execution Arguments cheetah handle of a Cheetah adapter Return Value The number of bytes to be sent by the Cheetah device across the SPI bus Specific Error Codes CH SPI BATCH EMPTY QUEUE The queue was empty CH SPI ASYNC MAX REACHED The maximum number of outstanding asynchronous batches has been reached CH SPI ASYNC EXCESS DELAY The queue has a queued delay after the last shifted byte which is not permissible for asynchronous batch shifting Details This function will submit the current batch queue asynchronously to the Cheetah A temporary outgoing buffer will be created to store the batch queue An internal incoming buffer will be also created to asynchronously capture the slave response data The application programmer does not have to explicitly manage these two buffers The function will immediately return after queuing this batch onto the USB rather than waiting for the shift to complete on the SPI bus 42 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual At this point the application can submit another batch to the queue This can be done immediately by submitting the same queue a second time without altering it the application simply needs to call ch_spi_async_ submit again Or the application may clear the queue and assemble a different batch all together see the ch_spi_queuefamily of functions Any subsequent calls to ch spi async submit will again c
25. ion It is a zero based number Return Value This function returns a Cheetah handle which is guaranteed to be greater than zero if valid Specific Error Codes CH UNABLE TO OPEN The specified port is not connected to a Cheetah device or the port is already in use CH INCOMPATIBLE DEVICE There is a version mismatch between the DLL and the hardware The DLL is not of a sufficient version for interoperability with the hardware version or vice versa See ch_open_ext for more information Details This function is recommended for use in simple applications where extended information is not required For more complex applications the use of ch_ open ext is recommended Open a Cheetah device ch_open_ext Cheetah ch open ext int port number CheetahExt ch ext Open the Cheetah port returning extended information in the supplied structure Arguments port number same as ch open ch ext pointer to pre allocated structure for extended version information available on open 25 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual Return Value This function returns a Cheetah handle which is guaranteed to be greater than zero if valid Specific Error Codes CH UNABLE TO OPEN The specified port is not connected to a Cheetah device or the port is already in use CH INCOMPATIBLE DEVICE There is a version mismatch between the DLL and the hardware The DLL is not of a sufficient version for interoperability wit
26. ires multi threaded use of the Cheetah functionality each Cheetah API call can be wrapped with a thread safe locking mechanism before and after invocation It is the responsibility of the application programmer to ensure that the Cheetah open and close operations are thread safe and cannot happen concurrently with any other Cheetah operations However once a Cheetah device is opened all operations to that device can be dispatched to a separate thread as long as no other threads access that same Cheetah device 3 8 2 USB Scheduling Delays More specifically each API call that is used to send data to and from the Cheetah adapter can incur up to 125 us 1 ms in delay on the PC host for USB High Speed Full Speed connections This is caused by the inherent design of the USB architecture The operating system will queue any outgoing USB transfer request on the host until the next USB frame period The frame period is 125 us 1 ms Thus if the application attempts to execute several transactions in rapid sequence there can be 1 2 ms delay between each transaction plus any additional process scheduling delays introduced by the operating system The best throughput can be achieved for single transactions that transfer a large number of bytes at a time 20 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 4 Firmware 4 1 Philosophy The firmware included with the Cheetah adapter provides for the analysis of the supported protoco
27. le 30 60 seconds per device 2 When the installation is complete the Found New Hardware notification bubble will again pop up and state that your new hardware is installed and ready to use Windows Vista 7 1 A notification bubble will pop up from the system tray and state that Windows is installing device driver software 2 When the installation is complete the notification bubble will again pop up and state that the device driver software installed successfully To confirm that the device was correctly installed check that the device appears in the Device Manager To navigate to the Device Manager screen select Control Panel System Properties Hardware Device Manager for Windows XP or select Control Panel Hardware and Sound Device Manager for Windows Vista 7 The Cheetah adapter should appear under the Universal Serial Bus Controllers section for Windows XP Vista 7 3 2 2 Driver Removal The USB communication driver can be removed from the operating system by using the Windows program removal utility Instructions for using this utility can be found below Alternatively the Uninstall option found in the driver installer can also be used to remove the driver from the system Note It is critical that all Total Phase devices have been removed from your system before removing the USB drivers Windows XP 1 Select Control Panel Add or Remove Programs 2 Select Total Phase USB Driver and select Chan
28. les cycles of delay to add to the outbound shift Return Value Returns the actual number of cycles of delay that were queued Specific Error Codes None Details Queues cycles amount of delay on the bus These are in units of clock cycles as set with ch_ spi bitrate The delays can only be queued in multiples of 8 The 39 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual function will return the actual number of cycles queued The requested number of cycles will be rounded up to the next multiple of 8 The requested number of cycles must be greater than zero and less than or equal to 232 9 If the requested number of cycles is out of bounds no delay is queued and the function will return 0 Gueue a Delay in Nanoseconds ch_spi_gueue delay_ns int ch spi queue delay ns Cheetah cheetah int nanoseconds Gueue a delay value on the bus in units of nanoseconds Arguments cheetah handle of a Cheetah adapter nanoseconds amount of time for delay in nanoseconds Return Value Returns the actual number of nanoseconds of delay that were gueued Specific Error Codes None Details Gueues nanoseconds amount of delay on the bus The fundamental unit of delay that can be queued on the Cheetah SPI bus is 8 times the clock period Therefore reguested delay will be rounded up to the next even multiple of this time span The function will return the actual number of nanoseconds gueued The reguested number of nan
29. ls It is installed at the factory during manufacturing Updates to this firmware are provided through a device upgrade utility The Cheetah software automatically detects firmware compatibility and will inform the user if an upgrade is required 4 2 Procedure Firmware upgrades should be conducted using the procedure specified in the README txt that accompanies the particular firmware revision 21 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 5 API Documentation 5 1 Introduction The API documentation describes the Cheetah Rosetta C bindings 5 2 General Data Types The following definitions are provided for convenience typedef unsigned char u08 typedef unsigned short ul6 typedef unsigned int u32 typedef unsigned long long u64 typedef signed char s08 typedef signed short s16 typedef signed int s32 typedef signed long long s64 5 3 Notes on Status Codes Most of the Cheetah API functions return a status or error code back to the caller The complete list of status codes is provided at the end of this chapter All of the error codes are assigned values less than 0 separating these responses from any numerical values returned by certain API functions Each API function can return one of two error codes with respect to the loading of the Cheetah DLL CH_UNABLE TO LOAD LIBRARY and CH INCOMPATIBLE LIBRARY If these status codes are received refer to the previous sections in this datasheet that discuss
30. lugged while being used These common status responses are not reiterated for each function Only the error codes that are specific to each API function are described below All of the possible error codes along with their values and status strings are listed following the API documentation 5 4 General 5 4 1 Interface Find Devices ch_find_devices int ch_find devices int nelem ul6 devices Get a list of ports to which Cheetah devices are attached Arguments nelem Maximum size of the array devices array into which the port numbers are returned Return Value This function returns the number of devices found regardless of the array size Specific Error Codes None Details Each element of the array is written with the port number Devices that are in use are OR ed with CH PORT NOT FREE 0x8000 Under Linux such devices correspond to Cheetah adapters that are currently in use Under Windows such devices are currently in use but it is not Known if the device is a Cheetah adapter 23 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual Example Devices are attached to port 0 1 2 Ports 0 and 2 are available and port 1 is in use devices 0x0000 0x8001 0x0002 If the input array is NULL it is not filled with any values If there are more devices than the array size as specified by nelem only the first ne lem port numbers will be written into the array Find Devices ch_fi
31. ms u32 drv revs for sw Software requires that the API interface must be gt this version u16 api req by sw All version numbers are of the format major lt lt 8 minor example v1 20 would be encoded as 0x0114 The structure is zeroed before the open is attempted It is filled with whatever information is available For example if the hardware version is not filled then the device could not be queried for its version number This function is recommended for use in complex applications where extended information is required For simpler applications the use of ch_open is recommended Close a Cheetah ch close int ch close Cheetah cheetah Close the connection to the given Cheetah 27 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual Arguments cheetah handle of a Cheetah adapter to be closed Return Value The number of adapters closed is returned on success This will usually be 1 Specific Error Codes None Details If the handle argument is zero the function will attempt to close all possible handles thereby closing all open Cheetah adapters The total number of Cheetah adapters closed is returned by the function Get Port ch_port int ch port Cheetah cheetah Return the port number for this Cheetah handle Arguments cheetah handle of a Cheetah adapter Return Value The port number corresponding to the given handle is returned It is a zero based num
32. n executable or in another directory such that it will be found by the previously described search rules 3 7 2 Versioning Since a new Cheetah DLL can be made available to an already compiled application it is essential to ensure the compatibility of the Rosetta binding used by the application e g cheetah c against the DLL loaded by the system A system similar to the one employed for the DLL Firmware cross validation is used for the binding and DLL compatibility check Here is an example DLL v1 20 compatible with Binding gt v1 10 Binding v1 15 compatible with DLL gt v1 15 The above situation will pass the appropriate version checks The compatibility check is performed within the binding If there is a version mismatch the API function will return an error code CH INCOMPATIBLE LIBRARY 3 7 3 Customizations While the provided language bindings stubs are fully functional it is possible to modify the code found within this file according to specific reguirements imposed by the application designer For example in the C bindings one can modify the DLL search and loading behavior to conform to a specific paradigm See the comments in cheetah c for more details 19 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 3 8 Application Notes 3 8 1 Threading The Cheetah DLL is designed for single threaded environments so as to allow for maximum cross platform compatibility If the application design requ
33. nd_devices_ext int ch find devices ext int num devices ul6 devices int num ids u32 unigue ids Get a list of ports and unique IDs to which Cheetah devices are attached Arguments num devices maximum number of devices to return devices array into which the port numbers are returned num ids maximum number of device IDs to return unigue ids array into which the unique IDs are returned Return Value This function returns the number of devices found regardless of the array size Specific Error Codes None Details This function is the same as ch_find devices except that it also returns the unique IDs of each Cheetah device The IDs are guaranteed to be non zero if valid The IDs are the unsigned integer representation of the 10 digit serial numbers The number of devices and IDs returned in each of their respective arrays is determined by the minimum of num_devices and num_ids However if either array is NULL the length passed in for the other array is used as is and the NULL 24 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual array is not populated If both arrays are NULL neither array is populated but the number of devices found is still returned Open a Cheetah device ch_open Cheetah ch open int port number Open a connection to the Cheetah at the given port Arguments port number The Cheetah port number This port number is the the same as the one obtained from the ch find devices funct
34. nic components are rated for standard commercial specifications 0 70 C However the plastic housing along with the ribbon and USB cables may not withstand the higher end of this range Any use of the Cheetah device outside the room temperature specification will void the hardware warranty 2 5 SPI Signaling Characteristics 2 5 1 SPI Waveforms The SPI signaling is characterized by the waveforms in Figures 5 and 6 6 TOTAL PHASE Cheetah SPI Host Adapter User Manual MOS pe jet Iel rr wo v Ts T Figure 5 above SPI Timing Requirements SS Cac tud tud Figure 6 above SPI Byte Level Timing Table 1 SPI Timing Parameters Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual User Insertable Delay 8 222 tak 1 The above timings only correspond to actions performed within a given SPI transaction Actions that span transactions will be subject to inter transaction USB delays However many SPI packets delineated by SS assert deassert can be sent within a single transaction 2 User insertable delays are guantized in blocks of 8 clock cycles 3 A user delay can be inserted to stretch te tsac OF tesa as needed sac 4 There is normally no gap between data bytes although a user delay can be inserted between bytes if the target SPI slave device needs time to process each received byte 5 The MOSI hold time t can be longer than half of one clock period depending
35. not need multiple threads if it can process the data between steps 2 and 3 and guarantee the algorithm will not take too long to process the incoming data 5 6 Error Codes Table 7 Cheetah API Error Codes Literal Name ch_status_string return value CH_OK O ok CH_UNABLE_TO_LOAD_ LIBRARY unable to load library CH UNABLE TO LOAD DRIVER unable to load USB driver 4 incompatible library version OH INCOMPATIBLE LIBRARY 4 CH INCOMPATIBLE DRIVER e ncompatible ariver version cn nee To oren 8 CH_UNABLE TO cose unable o cose devoe 0 inva CH_INVALID HANDLE 10 invalid device handle CH CONFIG ERROR configuration error CH UNABLE TO LOAD FUNCTION unable to load binding function _IU unable to open device 45 amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 46 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 6 Legal Contact 6 1 Disclaimer All of the software and documentation provided in this datasheet is copyright Total Phase Inc Total Phase License is granted to the user to freely use and distribute the software and documentation in complete and unaltered form provided that the purpose is to use or evaluate Total Phase products Distribution rights do not include public posting or mirroring on Internet websites Only a link to the Total Phase download area can be provided on such public websites Total Phase shall in no event be liable to any party for direct
36. on the exact MOSI propagation time However the maximum guaranteed hold time is O 5 t gik 6 The parameters t and t differ based on mode and polarity For example tac 6 5 and t 4 2 0 clock periods for modes 0 and 2 Likewise t 7 0 and t sa 1 5 clock periods for modes 1 and 3 2 5 2 Speeds The Cheetah device has a flexible clock generator that can produce SPI clock rates ata very fine granularity The minimum bit rate is 100 Hz and the maximum settable bit rate is 50 MHz Many intermediate bit rates are available often with a 1 2 kHz precision The Cheetah software and hardware have been meticulously designed to ensure maximal average throughput over the USB bus In other words if the SPI clock rate is set to 30 MHz the average data rate across an entire transaction will be nearly 30 Mbps end to end from host PC to SPI target device This property holds even for very large transactions ranging from hundreds of kilobytes to many megabytes long This high throughput feature is only possible within a single transaction Multiple transactions will suffer unavoidable USB bus latencies Hence the best throughput can be achieved for single transactions that transfer a large number of bytes at a time Rarely there can be delays across the USB bus even within a transaction While there will be a delay in the outgoing SCLK while the Cheetah adapter is paused waiting for 10 Na amp TOTAL PHASE Cheetah SPI Host Adapte
37. oper configuration for the SPI communication This architecture for the Cheetah API allows for maximum flexibility of the control lines SS1 SS2 and SS3 and provides for a mechanism to avoid expensive USB scheduling delays as described in a previous section of this datasheet For example one can send several separate SPI packets with the following sequence 1 Assert the OE 2 Assert the appropriate SS gueue the data and deassert SS Add optional delay on the bus Assert the appropriate SS gueue the data and deassert SS Repeat the last two steps as many times as desired O o A o Call the batch shift function This grouping of packets into a single transactions can be very efficient for programming devices such as EEPROMs or flash memories that require a separate SPI packets for each page that needs to be written The delay step would then correspond to the page write time specified in the memory s datasheet Note that the ch spi_batch_ shift function will only return to the caller after the entire queue has been shifted on the SPI bus There is an alternative non blocking implementation that can be used in lieu of ch spi batch shift The functions ch spi async submit and ch spi async collect allow the user to submit a batch gueue and perform other tasks including assembling and submitting a subseguent queue before collecting the results of the initial SPI shift operation This is an advanced feature that has tradi
38. opriate permissions for the Cheetah adapter 1 As superuser unpack 99 totalphase rules to etc udev rules d 2 chmod 644 etc udev rules d 99 totalphase rules 14 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 3 Unplug and replug your Cheetah adapter s 3 3 2 USB Hotplug USB hotplug requires two configuration files which are available on the software CD and also listed on the Total Phase website for download These files are cheetah and cheetah usermap Please follow the following steps to enable hotplugging 1 As superuser unpack cheetah and cheetah usermap to etc hotplug usb 2 chmod 755 etc hotplug usb cheetah chmod 644 etc hotplug usb cheetah usermap Unplug and replug your Cheetah adapter s ao A Oo Set the environment variable USB DEVFS_ PATH to proc bus usb 3 3 3 World Writable USB Filesystem Finally here is a last ditch method for configuring your Linux system in the event that your distribution does not have udev or hotplug capabilities The following procedure is not necessary if you were able to exercise the steps in the previous subsections Often the proc bus usb directory is mounted with read write permissions for root and read only permissions for all other users If an non privileged user wishes to use the Cheetah adapter and software one must ensure that proc bus usb is mounted with read write permissions for all users The following steps can help setup the correct
39. oseconds must be greater than zero and less than or egual to 2 seconds If the reguested number of nanoseconds is out of bounds no delay is queued and the function will return 0 Get Shift Length ch_spi_batch_ length int ch spi batch length Cheetah cheetah Returns the number of data bytes in the gueue Arguments cheetah handle of a Cheetah adapter 40 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual Return Value Returns the number of data bytes in the queue This does not include the commands SS assertion OE etc It only corresponds to the number of bytes that will be shifted out on the SPI bus The value returned is also the number of bytes to expect from the slave device when the currently queued commands are executed Specific Error Codes None Details None Execute SPI Shift ch_spi_batch_shift int ch spi batch shift Cheetah cheetah int num bytes u08 data in Perform the SPI shift operations in the queue Arguments cheetah handle of a Cheetah adapter num bytes number of bytes to put into data in data in buffer to place data received from slave device Return Value The number of bytes sent by the Cheetah device across the SPI bus Specific Error Codes CH SPI BATCH EMPTY QUEUE The queue was empty Details This function performs all of the accumulated commands in the queue and shifts them in order onto the SPI bus After the operation completes the batch queue is not cleared
40. permissions Please note that these steps will make the entire USB filesystem world writable 1 Check the current permissions by executing the following command ls al proc bus usb 001 2 If the contents of that directory are only writable by root proceed with the remaining steps outlined below 3 Add the following line to the etc fstab file none proc bus usb usbfs defaults devmode 0666 0 0 4 Unmount the proc bus usb directory using umount 5 Remount the proc bus usb directory using mount 15 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 6 Repeat step 1 Now the contents of that directory should be writable by all users 7 Set the environment variable USB DEVFS PATH to proc bus usb 3 4 Mac OS X USB Driver The Cheetah communications layer under Mac OS X does not require a specific kernel driver to operate Both Mac OS X 10 4 Tiger and 10 5 Leopard are supported It is typically necessary to ensure that the user running the software is currently logged into the desktop No further user configuration should be necessary 3 5 USB Port Assignment The Cheetah adapter is assigned a port on a sequential basis The first adapter is assigned to port 0 the second is assigned to port 1 and so on If a Cheetah adapter is subsequently removed from the system the remaining adapters shift their port numbers accordingly Hence with n Cheetah adapters attached the allocated ports will be numbered from 0 to n
41. r User Manual more data to shift out the average throughput will not be diminished appreciably since such events happen so infrequently 2 5 3 Pin Driving The Cheetah adapter can be connected or disconnected from the bus through software control Namely the device can either drive its outputs or place them in high impedance mode When in high impedance mode the Cheetah device will hold the last value of the output lines with very weak pull up or pull down resistances When connected to the bus the Cheetah adapter persistently holds the state of the SS lines across different shift transactions Hence if the SS line is left asserted after one transaction it will stay asserted until modified in a subsequent transaction 11 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 3 Software 3 1 Compatibility 3 1 1 Overview The Cheetah software is offered as a 32 bit or 64 bit Dynamic Linked Library or shared object The specific compatibility for each operating system is discussed below Be sure the device driver has been installed before plugging in the Cheetah adapter 3 1 2 Windows Compatibility The Cheetah software is compatible with Windows XP SP2 or later 32 bit and 64 bit Windows Vista 32 bit and 64 bit and Windows 7 32 bit and 64 bit Windows 2000 and legacy 16 bit Windows 95 98 ME operating systems are not supported 3 1 3 Linux Compatibility The Cheetah software is compatible with all standard 32
42. reate a temporary outgoing buffer and copy the current batch into it Likewise a temporary incoming buffer will also be created Note that the submitted batch should be sufficiently long in real time so that it does not complete before the application can submit more batches and also collect the first batch This will allow the adjacent batches to shift with very little delay between them How long to be safe First there is always the possibility that the applications process could be scheduled out by the operating system before it has an opportunity to submit the subsequent batch The operating system scheduler timeslice may be as much as 10ms Therefore submitted batches should be long enough to bridge one if not two time slices Second if the application is performing its own functions between the submission of two batches the length of the batches should be long enough to accommodate the CPU time of those functions Keep in mind that there can significant memory overhead for each asynchronous batch 1 Up to 4 times the size of the outgoing number of bytes In the worst case if there are no sequential repeats of data the outgoing buffer is approximately twice the size of the number of bytes shifted out on the SPI bus this doesnt count SS assert deassert commands or intermediate delays and there is potentially another factor of two due to kernel user mode memory allocation So if the application shifts 10 KB out in one batch the o
43. s and distributors from any and all claims arising from such use even if such claim alleges that Total Phase was negligent in the design or manufacture of its product 6 3 Contact Information Total Phase can be found on the Internet at http www totalphase com If you have support related questions please go to the Total Phase website For sales inquiries please contact sales totalphase com 47 Na TOTAL PHASE Cheetah SPI Host Adapter User Manual 2006 2014 Total Phase Inc All rights reserved 48
44. s always transferred in both directions in SPI but an SPI device interested in only transmitting data can choose to ignore the receive bytes Likewise a device only interested in the incoming bytes can transmit dummy bytes Each device has its own SS line The master pulls low on a slaves SS line to select a device for communication 6 TOTAL PHASE Cheetah SPI Host Adapter User Manual The exchange itself has no pre defined protocol This makes it ideal for data streaming applications Data can be transferred at high speed often into the range of the tens of megahertz The flipside is that there is no acknowledgment no flow control and the master may not even be aware of the slaves presence 1 1 3 SPI Modes Although there is no protocol the master and slave need to agree about the data frame for the exchange The data frame is described by two parameters clock polarity CPOL and clock phase CPHA Both parameters have two states which results in four possible combinations These combinations are shown in figure 2 Clock Phase CPHA CPHA O CPHA 1 0 CPOL MODE 0 MODE 1 Clock Polarity CPOL CPOL 1 MODE 2 MODE 3 Figure 2 SPI Modes The frame of the data exchange is described by two parameters the clock polarity CPOL and the clock phase CPHA This diagram shows the four possible states for these parameters and the corresponding mode in SPI 1 1 4 SPI Benefits and Drawbacks SPI is a very simple comm
45. tionally only been needed by a few users a detailed description is provided in the relevant API documentation The error code CH SPI ASYNC_ PENDING can be returned by other synchronous functions in the event that asynchronous batches are pending i e have not been yet collected 33 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 5 5 2 SPI Functions Set Bitrate ch_spi_bitrate int ch spi bitrate Cheetah cheetah int bitrate khz Set the SPI bitrate in kilohertz Arguments cheetah handle of a Cheetah adapter bitrate _khz the requested bitrate in kHz Return Value This function returns the actual bitrate set Specific Error Codes None Details The power on default bitrate is 1 MHz Only certain discrete bitrates are supported by the Cheetah adapter As such this actual bitrate set will be less than or equal to the requested bitrate unless the requested value is less than 100 kHz in which case the Cheetah adapter will default to 100 kHz The maximum supported speed for the Cheetah adapter is 50 MHz If bit rate khz is O the function will set the bit rate to the minimum value 100 kHz Configure SPI Bus Parameters ch_spi_configure int ch spi configure Cheetah cheetah CheetahSpiPolarity polarity CheetahSpiPhase phase CheetahSpiBitorder bitorder u08 ss polarity Configure the SPI interface Arguments cheetah handle of a Cheetah adapter 34 Na amp TOTAL PHASE Cheetah SPI Host
46. unication protocol It does not have a specific high level protocol which means that there is almost no overhead Data can be shifted at very high rates in full duplex This makes it very simple and efficient in a single master single slave scenario Because each slave needs its own SS the number of traces required is n 3 where n is the number of SPI devices This means increased board complexity when the number of slaves is increased Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual 1 1 5 SPI References Introduction to Serial Peripheral Interface Embedded com e SPI Serial Peripheral Interface 6 TOTAL PHASE Cheetah SPI Host Adapter User Manual 2 Hardware Specifications 2 1 Connector Specification The ribbon cable connector is a standard 0 100 2 54 mm pitch IDC type connector This connector will mate with a standard keyed boxed header Alternatively a split cable is available which connects to the ribbon cable and provides individual leads for each pin 2 1 1 Orientation The ribbon cable pin order follows the standard convention The red line indicates the first position When looking at your Cheetah adapter in the upright position Figure 3 pin 1 is in the top left corner and pin 10 is in the bottom right corner Figure 3 The Cheetah SPI Host Adapter in the upright position Pin 1 is located in the upper left corner of the connector and Pin 10 is located in the lower right corner of th
47. utgoing buffer overhead is approximately 40 KB 2 2 times the size of the incoming buffer for each batch 3 Size of the data_in buffer supplied to the ch_spi_async_ collect function Hence it is important to not queue many megabytes of batches with the asynchronous interface Additionally only a fixed number of batches can be submitted and be left pending prior to collection This number is fixed to 16 43 Na amp TOTAL PHASE Cheetah SPI Host Adapter User Manual Finally the asynchronous interface is only useful if the outgoing data of any asynchronous batch does not rely on the return MISO data of a previous asynchronous batch Collect an Asynchronous SPI Shift ch_spi_async_collect int ch spi async collect Cheetah cheetah int num bytes u08 data in Collect a previously submitted asynchronous SPI shift queue Arguments cheetah handle of a Cheetah adapter num bytes number of bytes to put into data in data in buffer to place data received from slave device Return Value The number of bytes sent by the Cheetah device across the SPI bus Specific Error Codes CH SPI ASYNC EMPTY There are no outstanding asynchronous batches to be collected Details This function can be called at anytime after submitting a batch for asynchronous processing It will block until the first pending batch completes For example if there are 5 batches outstanding this function will return after 1 batch has fully completed le
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