Application note - NXP Semiconductors
Contents
1. Fig 33 Descriptor file screenshot In usbdesc c there are several descriptors including 1 HID report descriptor 2 USB standard device descriptor 3 USB configuration descriptor 4 USB String descriptor Reading the comments associated with each line of code will give the idea some idea on what the descriptor will achieve For instance the Vendor and Product IDs are listed in the device descriptor The report structure and size gets listed in the report descriptor At this time let s focus our interest on the String Descriptor The strings present in this structure should match the strings on the Delphi application AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 28 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified Vendor Mame WXP Semiconductors Product Name Keil MCB2140 HID Serial dme DEMO Interface HID Hh Fig 34 Descriptor information screenshot Let s modify the Serial Number value from DEMO to 2148 Index Qed Serial Number 0x04 bLergth USB STRING DESCRIPTOR TYPE f biesoriptortype D p0 E U M ote OS ay Oo OF OT ee oo PS Index O4 Serial Number 0x04 bLength USB STRING DESCRIPTOR TYPE f bDescriptorType Ve ple aes eel es ae Be oyy Just with these changes build the library Update the library file in the Blinky project and build the Blinky application as2. i Build the HID library Copy the new HID lib file to the Blinky project folder 0O A W N Re connect the ULINK to the MCB2148 board Build the Blinky project and load the user application into the LPC2148 Go through the bus enumeration process Now open the Delphi application The application will not be able to recognize the LPC2148 because the vendor and product ids don t match WW NXP LPC214x HID Example Seles Mam NXP Semiconductors uct Mane Keil MCB2140 HID Tr P By fit m P M P m P M P mP m Pp INT1 not pressed MCB 1 40 Board not detected Fig 31 Delphi application screenshot Note For a host application to recognize the device firmware they should have the same Vendor and Product IDs 5 2 Descriptors Let s try to understand some aspects of descriptors Below we were able to enquire some information from the device AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 27 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified Vendor Mame WXP Semiconductors Product Name Keil MCB2140 HID Serial dme DEMO Interface HID Hh Fig 32 Descriptor information screenshot Let s open the descriptor file within the HID Uv2 project Project Workspace Eh MCB2140 Board 4 Source Code r usbcfg h E E usbhw c E hiduser c
3. cceeeeeeeeeees 12 User application Blinky ccccecceeeeseeeeeeeees 13 HID library LPC2148 firmware c c0cccceee 13 Host application DeIphl ccccessseeeeeeeeeeees 13 So 0 e E ae ners E en E E ere E rere 14 Configuring the library ccccceeeccceeeeeeeeeeeeeeeees 15 Vendor ID and Product ID ccceecceeeeeeeeee eee 15 FUO TSO Iocs arere a R 16 The HID API interface cccccceeeeeeeeeeeeeeeeeees 16 USB Init address of GetInReport address of SetOUtREport ccccccccsssseeeeeeeeeseeeeeeeeeeeeeeas 17 USB_Connect Boolean ccccccsseeeeeeeeeeeeees 17 GetlnReport void and SetOutReport void 17 Building the HID library and user blinky ADDING AU ON Pee 19 Building the HID library ccccsseceesseeeeeeeeeeens 19 Step 1 Change project settings to create a ibrary QUUDUN sacecccxcsae cecescuaseedseredeerscesceconeceeeses 19 Step 2 Build the library cccccccccessseeeeeeeeeees 20 Building the user application Blinky 20 Running the LPC2148 with the Delphi application pine ctee tar A E E A wonsteustatavestees 21 BUS enumeration ccccceececeeeeeeeeeeeeeeeseeeeseeeeees 21 IN and OUT flow of data cccccccceseseeeeeeeees 22 Host application functions ccccecseeeeeeeeeeeees 24 BOI ISE aal 26 Changing the vendor and product ID 26 IDDESGCIDIONS sucscesienct
4. respectively as shown in the figure below Under the HID class support wizard it can be seen that the HID package is configured to send and receive 1 byte through two arrays InReport and OutReport respectively These arrays are declared as global structures in the library and hence will be available to the user application Also the polling interval from the host for both IN and OUT transactions is set at 8ms Here polling interval means that the host will request a report from the device every 8ms using an IN transaction and it will send a report to the device every 8ms using an OUT transaction At this time we are just planning to enumerate the LPC2148 as a generic HID device As ageneric HID device the LPC2148 will be able to manage simple communication between the host and device 4 3 The HID API interface The HID library provides four basic APIs that would illustrate the functioning of the HID class These APIs without parameters are shown in the below image AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 16 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified HID USB Library USB Init USB Connect GetinReport SetOutReport SS3 SSS InReport OutReport Fig 17 HID library APIs 4 3 1 USB _ Init address of GetinReport address of SetOutReport This function handles the initialization of the USB interfa
5. Information in this document is believed to be accurate and reliable However NXP Semiconductors does not give any representations or warranties expressed or implied as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information Right to make changes NXP Semiconductors reserves the right to make changes to information published in this document including without limitation specifications and product descriptions at any time and without notice This document supersedes and replaces all information supplied prior to the publication hereof AN10736_1 LPC214x USB simplified Suitability for use NXP Semiconductors products are not designed authorized or warranted to be suitable for use in medical military aircraft space or life support equipment nor in applications where failure or malfunction of a NXP Semiconductors product can reasonably be expected to result in personal injury death or severe property or environmental damage NXP Semiconductors accepts no liability for inclusion and or use of NXP Semiconductors products in such equipment or applications and therefore such inclusion and or use is for the customer s own risk Applications Applications that are described herein for any of these products are for illustrative purposes only NXP Semiconductors makes no representation or warranty that such applications will be suitable for the specified use with
6. that there has been a change in transfer type During bus enumeration the device and the host communicate using Control transfers and then depending upon the application the transfer type will shift to Interrupt Isochronous or Bulk In this case the LPC2148 is enumerating as a generic HID device So the transfer type will switch to Interrupt transfer One can find out the exact switch of the transfer type by analyzing the communication over a USB protocol analyzer Control Transfer on Endpoint 0 Bus enumeration E bate Eki interrupt Transfer on buffer buffer Endpoint 7 Host application is now in control Fig 26 Host timeline NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 23 of 35 NXP Semiconductors AN1 0736 AN10736_1 4 5 2 LPC214x USB simplified As shown in Fig 26 the red arrow indicates a timeline The host at some point in time will switch from Control to Interrupt Now the host will continuously poll the device for reports and send a report to the device when the user updates the application Host application functions 1 One can get more information on the device by clicking on the top buttons from Vendor Name all the way down to Interface When these buttons are clicked the Delphi application will get this information from descriptors that were exchanged during the enumeration process As mentioned earlier descriptors are structures that pro
7. well Download the code into the LPC2148 and let it enumerate If the Delphi application is open then wait for the bottom bar to become green Once the device is detected click on the buttons again and you will get the information from the updated descriptors as shown below AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 29 of 35 NXP Semiconductors AN10736 LPC214x USB simplified a a P a a P NAP LPC214x HID Example P1 16 P1i 17 P1 18 Product Mame Product Name P1 19 P1 20 Serial Number 2148 P1 21 P1 22 Interface Interface P1 23 vendor Mame Vendor Name INT1 not pressed MCB 140 Board dete Fig 35 Updated descriptor screenshot aaa 5 3 Host applications Delphi 5 3 1 Software This document would not be complete without discussing a few points regarding the Delphi application An evaluation version of the Delphi 2007 for Win32 software can be downloaded from the following website http Awww nxp com redirect codegear com win32 The Delphi application comes with complete source code and project files Along with this package we also used a HID component that acts like a bridge between the application and the HID device driver This HID component can be downloaded for free from the following website http www nxp com redirect soft gems net This component gives complete access to the L
8. 008 15 of 35 NXP Semiconductors AN10736 LPC214x USB simplified application should have the same matching IDs for it to recognize the LPC2148 We will revisit this in Section 4 Project Workspace E MCB2140 Board 59 Source Code i UsbeFg h usbhw c usbcore c usbdesc c Vendor and 1 usbuser c Product ID s H hiduser c Data that goes InReport lt into the host l Data that goes OutReport S out of the host Files Regs Books M Functions Fig 16 Vendor product ID screenshot a Templates Expand All Collapse an option USB Configuration USE Power vendor ID Product ID Max Number of Interfaces Max Number of Endpoints Max Endpoint 0 Packet Size USB Event Handlers Human Interface Device HID Configuration Interface Nurnber Report Bytes In In Report Polling Interval Report Bytes Gut Out Report Polling Interval Text Editor_ Configuration Wizard usbohg hi Help Value SelF powered OxO04CC 0x1235 1 4 64 Bytes 4 2 2 HID report In the HID class data is exchanged between the host and the device in structures called reports During bus enumeration the device will inform the host the format of the report In this case the report structure is a simple array and the size is configurable In the configuration wizard the size of IN and OUT reports are set by Report Bytes In and Report Bytes Out
9. 1 2 Step 2 Build the library Let s go ahead and build the library JA Fe pA EIT Board Bh IWW i y y o E E aa Board Fig 21 Step 2 screenshot The HID lib file gets created in the Obj folder A copy of this file already exists in the Blinky folder If any changes are made to the library then the new HID lib file should be copied to the Blinky folder 4 4 2 Building the user application Blinky The Blinky example is all set to build However if the user wishes to add the library to this application then a simple step needs to be carried out In the project workspace simply create a new group called Library show on left below Right click on the Library folder and click on Add files to Group Library Under files of type select lib files and then select HID lib AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 20 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified Add Files to Group Library Lookin Blinky J e m aa Project Workspace Flash Ha meeziae Flash oie H E Startup Code m General ARM r Startup ia taruna Startup File H E Source Code demo_delphi c l gt Demo C file Documentation i Abstract txt E E Library HIC lib iy HID Library File name Files of type Library file lib Fig 22 Blinky screenshot Let s buil
10. AN10736 LPC214x USB simplified API approach to HID class Rev 01 12 August 2008 Application note Document information Info Content Keywords USB device LPC214x HID software library USB 2 0 Abstract This document will enable the user to start using the LPC214x USB 2 0 Device peripheral in a matter of hours It also covers the basics of the USB 2 0 protocol and explains the API interface for the HID software library founded by Philips NXP Semiconductors AN1 0736 LPC214x USB simplified Revision history Rev Date Description 01 20080812 Initial version Contact information For additional information please visit http www nxp com For sales office addresses please send an email to salesaddresses nxp com AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 2 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified 1 Introduction The LPC214x family of microcontrollers is comprised of 64 pin ARM 7 based devices that contain a range of peripherals including a USB 2 0 full speed device controller This device series can be equipped with up to 512 kB of on chip flash memory and they can run at a maximum speed of 60 MHz The patented Memory Accelerator Module MAM together with the 128 bit wide flash makes these chips a great choice for USB based applications In general USB programming is a challenge compared to other embedded serial int
11. OST WINCOW S PC Laptop o HID Driver HID USB Library DEVICE LPC214x API interface User Application Fig 8 USB host device software example 3 1 LPC214x device firmware TAD oo HID USB Library DEVICE LPC214x API interface User Application Fig 9 Device example In this package we are attempting to provide the HID software as a library to the user application As mentioned before the Keil HID Software is adopted The HID class details are now configurable using the modified configuration wizard that is provided in AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 11 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified this package Once configured the package should be imported to the user application as a library and then it can be accessed using a very simple API interface With this approach the user application need not understand the entire details of the USB protocol and focus all the attention on the application The APIs are explained in detail in the following section 3 2 USB host details Delphi Application API interface HOST Windows PC Laptop HID Driver Fig 10 Host example On the host side we don t have to provide any device drivers for the HID Class Windows OS comes pre built with the HID class driver and it provides an API interface that could be used by PC based applications to create
12. PC2148 generic HID device AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 30 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified API interface HID Component Windows HID Driver Fig 36 HID component 5 4 Code snippets Out Report Because of the HID component sending an OUT report to the device becomes as simple as the below code snippet ff initialize the output report LPC2140 OutputReport ReportiIp 0 LPC2140 OutputReport LEDBits soo ff write the bits to the LPC2140 HID to reset the LEDs LPC2140 HID WriteFile LPC2140 OutputReport SilgeOf LPC2140 OGutputReport BytestWritten As seen above the OUT report gets initialized and then is sent downstream using a simple API LPC2140_HID Writefile Enumeration The HID component offers several events that can be used by the Delphi application In this application the following events are utilized the enumerate event the Device Data IN report event and Device Change The enumerate and device data events are discussed below AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 31 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified HidCtl TivHidDeviceController Properties Events E Onarrival OnDeviceChange HidCtiDeviceChange OnDeviceData HidCtibeviceData OnDeviceDataErroa
13. a but error correction is not a must The human ear would not be able to pick up small errors in audio samples every now and then Under normal circumstances a USB transfer should experience no more than a very occasional error due to line noise Control transfer All the above USB devices have to first go through the bus enumeration process As mentioned above bus enumeration is the process wherein the host gets to Know about the capabilities of the device A control transfer type follows a strict format for communication and all devices must support this transfer So if one follows a typical USB communication trace acquired from a USB protocol analyzer they would notice that all the initial communication is handled by control transfers and then depending upon the application the transfer type will switch to either Interrupt Bulk or Isochronous As an example a printer would use control transfer during the bus enumeration process and then switch to bulk transfers for transferring files and status information Device classes USB devices that share many attributes or request similar services are grouped within the same class specification A class specification defines functions that describe how the data will be transferred They also define the number and type of buffers that are supported by the class Classes make it easier to develop device drivers and firmware in a standardized way Windows and other operating systems include dri
14. a host application In this case we have chosen Delphi to create the host application 4 Running the USB application This section covers the following 1 Software setup explained Configuring the library The HID API interface Building the HID library and user application oF OO N Running the applications 4 1 Software setup explained This package comprises of the following packages AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 12 of 35 NXP Semiconductors AN1 0736 4 1 1 4 1 2 AN10736_1 LPC214x USB simplified gt tee Simplified USB E I HID Firmware Library Blinky User Application LPE2148 Firmware at HID Library Host Application Delphi Host Application Fig 11 Software packages User application Blinky The Blinky project is a typical first choice for running the first example on an evaluation board This also would be our choice for a user application After running this example one can hopefully realize how the API interfaces make it easy for the host and device to communicate The target of this project is the internal Flash of the LPC2148 This demo is all set to run with the Delphi Host Application and the Keil MCB 2140 board The HID Library file is configured accordingly HID library LPC2148 firmware This library is a modified version of the Keil HID example that was o
15. ce in the LPC2148 which includes resetting the USB interface and setting the address to 0 As mentioned in Section 2 1 during bus enumeration the LPC2148 would communicate with the host using Address 0 on Endpoint 0 This function takes the addresses of the two other APIs as parameters GetInReport void and SetOutReport void These two APIs are defined by the user application The HID library will be calling these functions at run time Hence dynamic binding had to be incorporated that enables the HID library to call these functions at runtime using function pointers 4 3 2 USB Connect Boolean This function initiates the connect sequence if the Boolean value is set to TRUE and initiates the disconnect sequence if the Boolean value is set to FALSE To be more precise it uses the SoftConnect feature of the LPC214x To get more information on SoftConnect please refer the LPC214x User Manual If the SoftConnect feature is not being used it is not necessary to call the USB_Connect function 4 3 3 GetlInReport void and SetOutReport void These two functions have to be defined by the user Let s revisit Section 2 4 and analyze some key points AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 17 of 35 NXP Semiconductors AN1 0736 AN10736_1 LPC214x USB simplified A OST OUT IN Endpoint Endpoint buffer buffer OV Device Fig 18 In out host transa
16. ctions with endpoints 1 The host and the device send and receive data using IN and OUT transactions and they use their respective IN and OUT buffers 2 Within the HID class data gets transferred between the host and the device using reports Reports can have a flexible format in this case they are simple arrays The size of these arrays are set by the USB configuration wizard Section 4 2 1 3 The host will poll the device at regular intervals and request send reports So the above figure can be further expanded to the following E HOST 5 E Endpoint Endpoint buffer buffer Fig 19 Data accumulation in OutReport As shown above data sent from the host will get accumulated in OutReport Similarly data that needs to be sent to the host needs to get accumulated in InReport When host requests the data the HID library will empty the InReport into the respective IN buffer endpoint GetInReport will be called by the HID Library when host requests a report from the device User has to define GetInReport and fill the InReport accordingly SetOutReport will be called by the HID library when host has sent a report for the device User has to define SetOutReport and empty the OutReport accordingly NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 18 of 35 NXP Semiconductors AN1 0736 4 4 4 4 1 4 4 1 1 AN10736_1 LPC214x USB simp
17. d attempt to understand the USB interface on both the device and host side 5 1 Changing the vendor and product ID Let s try to understand the significance of Vendor and Product IDs Please double click on their values and change it any other hex value Project Workspace x 5 MCB2140 Board Expand All Collapse AIl Help H E Source Code usbefg h Option value H 4 usbhw c USB Configuration usbcore c Vendor and USB Power Self powered yp 1 l usbdesc c vendor ID 0x04CC 4 usbuser c Product ID s ae ae Product ID 0x1235 4 hiduser c Max Number of Interfaces 1 Max Number of Endpoints 4 Max Endpoint 0 Packet Size 64 Bytes E DMA Transfer E USB Event Handlers ese Human Interface Device HID Configuration Data that goes Interface Number 0 nReportl em into the host AE i if In Report Polling Interval 32 ms Data that goes Report Bytes Out 1 OutReport a isha port out of the host Out Report Polling Interval 32 ms n aes a Text Editor Configuration Wizard Files Regs d Books Di Functions amp Templates usbelg h Fig 30 Changing vendor and product ID screenshot AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 26 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified After making the above modification to the HID uv2 project carry out the following steps
18. d is now ready for use AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 21 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified The below images were captured on Windows XP Professional Version 2002 Drivers Hardware Profiles fer Driver Signing lets you make sure that installed drivers are A compatible with Windows Windows Update lets you set up how Windows connects to Windows Update for drivers Driver Signing Windows Update H m Modems Hardware profiles pr different hardware confiqurations System Properties 12X m Device Manager USB Human Interface Device Properties System Restore Automatic Updates Remote f Fle Action View Help General Driver Details General Computer Name Hardware Advanced e H f8 2 Rg E USBSJIOBAY1INBMLYX 28 USB Human Interface Device Device Manager ey a Batteries The Device Manager lists all the hardware devices installed on H P Computer your computer Use the Device Manager to change the properties See Disk drives Device type Human Interface Devices of any device H rg Display adapters Manufacturer Standard system devices 7 i eo Location Location 0 Keil MCB2140 HID Ma Human Interface Devices a HID compliant device Device status Ea USB Human Interface Device i This device is working properly H S Keyboards lf you are having problems with this device cl
19. d the user application together with the HID library Click on the build button as shown below Once the application is built successfully load the code into the LPC2148 Flash by using the Load button as shown below Project Worksp o MCB2148 Flas q Startup Code A Startup s Build Load 4 6 Source Code A demo_delphi c x Ipc214x h tune h Fig 23 Build screenshot The LPC2148 is now ready to communicate with the Delphi host application 4 5 Running the LPC2148 with the Delphi application Let s run the application and at the same time try to relate this to our understanding of the USB protocol 4 5 1 Bus enumeration Let s see bus enumeration in action Please carry out the following steps 1 Disconnect the ULINK from the LPC2148 evaluation board 2 On the host side right click on the My Computer and browse to System Properties window 1 Then click on Device Manager window 2 will show up 3 Keeping this window open connect the LPC2148 over USB to the host PC Laptop As the LPC2148 undergoes bus enumeration the window will get updated 4 Once enumeration is completed the USB Human Interface Device icon should show up on Window 2 shown in red box below Double clicking on USB Human Interface Device should lead to window 3 5 This window identifies the USB HID device as a Keil MCB2140 HID This shows that the device has enumerated correctly an
20. e Rev 01 12 August 2008 3 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified Peo ee Ta o UB Speake Fig 1 USB host example The LPC214x microcontroller is a great fit for as a peripheral solution since it is equipped with USB device controller This IP follows the USB 2 0 specification and supports full speed 12Mbps transfers The USB 2 0 protocol also supports hi speed 480Mbps however it is not supported in the LPC214x This section covers the following 1 What happens when you plug in the USB cable 2 USB applications and transfer types 3 Device classes 4 How does data flow between the host and device 2 1 What happens when you plug in the USB cable The starting point of USB communication in the simplest form between the host and the device can be considered to be the plugging of the USB cable into the USB port of the host AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 4 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified Fig 2 Host hub port The host hub port Fig 2 is able to detect the attachment of the USB device and makes the host controller aware of the same The host controller then starts communicating with the USB device which could be a mouse keyboard flash drive etc This initial communication between the host and the device is termed as bus enumeration Bus enumeration is the p
21. erfaces since it involves a basic understanding of the USB protocol and the PC Laptop interface With this package we are attempting to simplify the whole USB 2 0 programming experience This package includes 1 LPC214x Keil firmware library and associated APIs 2 Delphi host application for HID Human Interface Device class HID is explained in Section 3 of this manual 3 This manual which explains the basics of the USB protocol and overall library operation The LPC214x firmware library is configurable and using the APIs the user application will be able to send and receive bytes from the host in a matter of hours This firmware library is the modified version of the Keil HID USB example and it provides four basic APIs to the user application The APIs hides the complexity of the USB protocol and successfully transfers all the focus on the application This manual attempts to cover all the dots and includes the following sections 1 Understanding USB from an application perspective 2 Software Overview 3 Running the USB application 4 Exercise 2 Understanding USB AN10736_1 USB is a host peripheral solution There is only one host and all the peripherals devices are connected to this particular host Please take note of the single host in this figure The host would typically be a PC or a laptop Connected to the host would be the various peripherals via USB hubs NXP B V 2008 All rights reserved Application not
22. esccccntdexcoictteaeitetectaciaceeieoseddetie 27 Host applications Delphl cccecseeeeeeeeeeeees 30 SOW secesie riea araea ORTA EAER 30 Code snippets nnnnnnoooannnnnnnennnnnenneennnnnnnnnennnni 31 founded by LPC214x USB simplified 6 References acces cc eee ccc ceeeedceeceeeecaueneacee 33 7 LOG al INFOMATION sissie 34 7 1 DefinitionS soso cess diceeepigoece tec poaetetcscoceecnacee sacs 34 7 2 Disclaimers seroren par ERRON 34 7 3 Trademarks aisaiinenneseenenenernernnnrnnrrerrnnrrnerrerrnnn 34 8 Contents s snsssnsnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn e 35 Please be aware that important notices concerning this document and the product s described herein have been included in the section Legal information NXP B V 2008 All rights reserved For more information please visit http www nxp com For sales office addresses email to salesaddresses nxp com Date of release 12 August 2008 Document identifier AN10736_1
23. h the INT1 status I NXP LPC214x HID Example Vendor Mame NXP Semiconductors Product Name Keil MCB2140 HID Serial Number DEMO Interface HID z s z z L z L ri Fig 28 INT1 status screenshot 3 Check boxes from P1 16 to P1 23 correspond to the LEDs on the board By checking these boxes one can set or clear the LED status on the MCB board Similar to IN reports checking the boxes will generate an OUT report to the device The HID library will then call SetOutReport in the user application that will enable or disable the LEDs on the board Lets analyze the current SetOutReport void function void SetOutReport void IOPIN1I IOPIN1 amp LEDMSK OutReport 0 lt lt 16 Hw GC PW Fe As shown above the value of OutReport gets sent to IOPIN1 which updates the LEDs accordingly Action OUT Flow of Data Click on the check boxes on the Delphi application and as the boxes are clicked the corresponding LEDs on the board should light up AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 25 of 35 NXP Semiconductors AN10736 LPC214x USB simplified Serial Number DEMO Interface HID INT1 not pressed MCB2140 Board detected Fig 29 Board detection screenshot Product Mame Keil MCB2140 HID JER vendor Mame NXP Semiconductors 5 Exercise In this section we will run some short exercises an
24. ick Troubleshootto star HTD Mice and other pointing devices the troubleshooter H z Monitors Hi Network adaa 1 B PCMCIA adapgers Troubleshoot oie a way for you to setup and store Device usage Use this device enable Hardware Profiles Cox JL Fig 24 Bus enumeration screenshots 4 5 1 1 AN10736_1 IN and OUT flow of data To see communication between the host and the LPC2148 let s open the Delphi Host Application Please open LPC214x_HID exe under the Delphi folder This application has the same Vendor ID and Product ID as set in the HID Library firmware Section 4 2 1 If these values are changed the host application will not be able to identify the LPC2148 Vendor ID Celle Prodiact IC iz If the above IDs are matched the LPC2148 board will get detected by the Delphi application and this will be indicated by the color of the bottom bar turning green NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 22 of 35 NXP Semiconductors AN1 0736 AN10736_1 LPC214x USB simplified 1 NXP LPC214x HID Example vendor Name Vendor Name 7 Product Name Product Name Serial Number Serial Number 1 Interface Interface INT1 not pressed MCB2 40 Board detected Fig 25 Delphi host application screenshot At this point bus enumeration is completed and the host is already polling the device for data This further means
25. ied E m LPT21 x Simplified USB 9 HID Firmware Library 9 Blinky a G lesen i Lst O Obj E Host Application C Delphi Fig 14 Firmware folder screenshot Now open the configuration wizard by clicking on 1 and 2 below 1 usbcfg h 2 Configuration wizard Project Workspace v x E ry MCB2140 Board Expand All Collapse All Help il Option Yalue Be ses USB Configuration a Ea usbcore c USB Event Handlers H 2 usbdesc c Human Interface Device HID Configuration usbuser c hiduser c Text Editor A Configuration Wizard Files Regs Qd Books et Functions amp Templates usbeta Fig 15 Configuration wizard screenshot AN10736_1 4 2 Configuring the library 4 2 1 Vendor ID and Product ID The configuration wizard provides a GUI for configuring the Vendor and the Product information in the form of Vendor and Product IDs Each vendor like NXP Semiconductors will have his own unique Vendor ID A Vendor ID can be obtained from the following website http Awww nxp com redirect usb org developers vendor Also each vendor can have several Product IDs Why is it important to know about Vendor and Product IDs Later on we will be invoking a host application that will be able to communicate with the LPC2148 This host NXP B V 2008 All rights reserved Application note Rev 01 12 August 2
26. lified NOTE The size of InReport and OutReport is set in the usb_api h file and this should match the size set in the configuration wizard Section 4 2 1 The usb_api h file is located in the Blinky folder 1 define USB_HID_REPORT_IN 1 2 define USB_HID_REPORT_OUT 1 For example if the report Bytes In and Report Bytes Out are set to 2 then the above definitions should also be set to 2 Report Bytes In I In Report Polling Interval 6 ms Report Bytes Out l Out Report Polling Interval 6 ms Building the HID library and user blinky application So far we have understood the HID library configuration wizard and we have also understood the HID API interface Let s go ahead and build the HID Library Building the HID library To build a library in the Keil environment carry out the following steps Step 1 Change project settings to create a library output NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 19 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified L40 Board Options for Target MCB2140 Board Device Target Output Listina User CC Asm Linker Debug Utilities Select Folder for Ubjects Name of Executable HID C Create Executable Obj HID I Debug Information Create Batch File I Create HEX File Browse Information Create Libram NObjMHID LIB OF Cancel Defaults Fig 20 Step 1 screenshot 4 4
27. ne configuration Bus enumeration is transparent to the user After the USB cable is plugged in the host enumerates the device Once enumeration is complete Windows adds the new device to the Device Manager display in the Control Panel The device is then configured and AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 5 of 35 NXP Semiconductors AN1 0736 2 2 2 2 1 LPC214x USB simplified ready to transfer data We will revisit bus enumeration when we run the actual example that is provided in this package USB applications and transfer types Let s look at some of the most common USB applications and try to understand the different types of USB transfers Interrupt transfer Fig 3 Keyboard and mouse Interrupt transfers are useful when data has to transfer within a specific amount of time Typical applications would include keyboard and mouse Fig 3 Users don t want a noticeable delay between pressing a key or moving a mouse and seeing the result on the screen Though the name interrupt transfer suggests the device can cause a hardware interrupt to the PC the truth is like all other USB transfers an interrupt transfer only happens when the host polls the device The transfer is interrupt like because there is a guarantee that the host will request or send data within a specified time interval i e polling interval Interrupt transfers are also popula
28. out further testing or modification 7 3 Trademarks Notice All referenced brands product names service names and trademarks are property of their respective owners NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 34 of 35 NXP Semiconductors AN10736 8 Contents 2 1 2 2 1 2 2 2 2 2 3 2 2 4 2 3 2 4 3 1 3 2 4 1 4 1 1 4 1 2 4 1 3 4 1 4 4 2 1 4 2 2 4 3 1 4 3 2 4 3 3 4 4 4 4 1 4 4 1 1 4 4 1 2 4 4 2 4 5 4 5 1 4 5 1 1 4 5 2 5 1 5 2 5 3 5 3 1 5 4 MTOdUCUON soises 3 Understanding USB ccsecsssessseeeeeeenseeseeeees 3 What happens when you plug in the USB cable 4 USB applications and transfer types 00 6 Interrupt tranSfer ccccccccseeeeceeeeeeceeseeseeeseeseees 6 Bulk transfer cccccsecccsececseeeeseeeeceeeeceeeeseeeessaees 6 lsochronous tranSfel ccccecceceeeeceeeeeeeeeeeeeeeeaes 7 Control TAS OT ace accainctcaicsots eioerinxte teveen veuicbuenniancanbatietes 7 Device classes ccccceeccceeeeeceeeceeeeseaeesseeeeseneesaes 7 How does data flow between the host and device E E E E ee 8 USB software OVEIrvVieW ccccsssseeeseeseeeeeees 10 LPC214x device firmware cccccecseeeeeeeeeeeees 11 USB host CCl Sse iccicarcacctionsndocivueaseseoantsagiueshatdvnnes 12 Running the USB application 00000 12 Software setup explained
29. r OnDeviceUnplug OnEnumerate HidCtlEnumerate OnRemoval Fig 37 Enumeration events screenshot The enumerate event is triggered when Windows is enumerating the LPC2148 On the application front the following function will be called As seen below the very first step after this event is to match the Vendor and Product ID s with that of the application const cMaP VID 04cc cLPC USB PID 1235 function TfrmMain Hidct lEnumerate const HidDew TJvHidDewice const Idx Integer Boolean var BytesUritten Cardinal begin if Hidbewv ttributes vendorIp cNXF WID and iHidDew Attributes Product ID cLPC USB PID then IN report The device data event occurs when the USB device has sent some data to the USB host This further means the HID component will trigger this event when a report is received from the LPC2148 On The application front the following function gets called AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 32 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified procedure T rmMain HidCtlbeviceDbata HidDev TJyvyHiddeyice ReportIp Byte const Data Pointer Size Word hegin if StrPas Datal lt gt then begin otaticText1i caption INT1 pressed staticTextl Color clRed staticTextl Font Color clCreat end else hegin staticTextil Caption INT1 not pressed staticTextl Color clCreanm sta
30. r because Windows includes class drivers that enable applications to do interrupt transfers that conform to the HID specification HID is explained later in section 2 2 2 Bulk transfer AN10736_1 Fig 4 Printer scanner and CD ROM NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 6 of 35 NXP Semiconductors AN1 0736 AN10736_1 2 2 3 2 2 4 2 3 LPC214x USB simplified When a file is sent for printing one typically does not care much of the speed at which the file reaches the printer However it is very important that the file reaches the printer without any errors Bulk transfers are useful for transferring data where time is not critical Typical applications would be printers scanners and CD ROMs Fig 4 A bulk transfer can send large amounts of data without creating congestion on the bus because other transfer types occur before bulk transfers On an otherwise idle bus bulk transfers are the fastest transfer type Bulk transfers detect errors and use data toggle bits to ensure that no data is lost lsochronous transfer Fig 5 USB speakers lsochronous transfers are streaming real time transfers that are useful when data has to arrive at a constant rate or by a specific time and occasional errors can be tolerated USB speakers Fig 5 would be an example of a product that uses isochronous transfers Such devices need a guaranteed delivery rate for dat
31. riginally developed for the LPC2148 The original Keil example can be obtained from the below website http www nxp com redirect keil com 306 asp The modifications though subtle helped us to create a simple library that simplifies the HID experience Once the library is created users have to just use four API calls to access it Host application Delphi A Delphi HID application is provided with complete project files and source code The user application i e Blinky is configured to run with the Delphi application Fig 12 shows a screenshot of the Delphi Application NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 13 of 35 NXP Semiconductors AN10736 LPC214x USB simplified Yendor Name Vendor Hame Product Name Product Mame ei pei pei ja jat Serial Number Serial Number i j l Interface Interface p p pP P P P P P peak INT1 not pressed MCB2140 Board not detected Fig 12 Screenshot of Delphi application 4 1 4 Setup USB Connections Fig 13 Setup example oo Configure the setup as shown in Fig 13 using the Keil MCB 2140 board and the Keil ULINK Please browse to the LPC2148 Firmware folder and open the HID uv2 project AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 14 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplif
32. rocess through which the host learns about the capabilities of the device Since any USB device can be connected to the host hub port at anytime bus enumeration becomes the essential first step of USB communication Bus enumeration includes the following key steps 1 Assigning an address to the device All devices on the USB bus will be given a unique address from the host However when any device starts communicating with the host it always start communicating using address 0 2 Reading data structures from the device As we know any peripheral can be connected to the USB Host hub port Hence each time a peripheral is connected the host will request a series of data structures from the device that will inform the host about its capabilities These data structures are called descriptors Descriptors will contain a range of information including details about the Vendor and the product Vendor and Product IDs will be covered in Section 4 3 Assigning and loading a device driver Using the information from the descriptors the host controller is now able find the device driver that can manage communication with the device 4 Selecting a configuration Once the device driver is loaded it will request a configuration from the device A device may have different configurations For example a high power device may also support a low power mode resulting in a configuration descriptor for each mode Most devices typically support only o
33. so has buffers at its end but they are not called endpoints So for any device it would have both IN and OUT endpoints All devices must have an IN endpoint 0 and OUT endpoint 0 since this is used by control transfer for bus enumeration Let s modify Fig 6 and show more details using endpoints AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 9 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified Mra r buffer buffer Device Fig 7 In out host transactions with endpoints 3 USB software overview In this package we have selected to use the HID class specification By using the HID class we are saving ourselves the trouble of creating a custom device driver on the host side Also there is a lot of support from the online community in terms of host applications For the LPC214x now a HID device to work correctly with our laptops USB Host the following software packages would be needed 1 USB Device in this case LPC21 4x e Device Firmware In the below figure this would constitute HID USB Library and User Application 2 USB Host typically PC laptop e Windows HID driver e Host Delphi Application AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 10 of 35 NXP Semiconductors AN10736 LPC214x USB simplified Delphi Application API interface rd y H
34. ticTextil Font Color clNavy end end SetOutReport sends a 0 or 1 depending upon the status of the INT1 button On the host side if the data is 1 then the text color changes to red else the text color remains cream 6 References Hopefully after reading the above chapters the reader has gained some insight into the USB interface and its protocol An essential next step would be to read some related documents on the USB protocol and the USB chapter of the LPC214x user manual e USB 2 0 Specification http Awww nxp com redirect usb org developers docs e The USB Complete book http Awww nxp com redirect Ilvr com usbc htm e Universal Serial Bus System Architecture e LPC214x UM and other related information http www standardics nxp com products lpc2000 lpc214x e Host applications for HID http Awww nxp com redirect lvr com hidpage htm AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 33 of 35 NXP Semiconductors AN10736 7 Legal information 7 1 Definitions Draft The document is a draft version only The content is still under internal review and subject to formal approval which may result in modifications or additions NXP Semiconductors does not give any representations or warranties as to the accuracy or completeness of information included herein and shall have no liability for the consequences of use of such information 7 2 Disclaimers General
35. vers for common classes If the device s class is supported by the operating system a driver for the device need not be provided for instance this applies to the HID class NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 7 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified Let s look at some of the most common classes se 9 1 Human Interface Device HID 2 Mass storage 3 Printer 4 Audio device 5 Imaging 2 4 How does data flow between the host and device Data flows IN and OUT with respect to the host If data is going from the device to the host it is called an N transaction and if the data is going from the host to the device it is called an OUT transaction as shown below A typical transfer control isochronous bulk interrupt is made of several transactions A transaction is in turn made of up several packets Fig 6 is a general picture that shows IN and OUT transactions with respect to the host AN10736_1 NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 8 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified Fig 6 In out host transactions On the device side data that needs to be sent to the host and data that is received from the host gets collected in an area called Endpoint An endpoint is a buffer that can store multiple bytes The host al
36. vide information on the capabilities of the device Section 2 1 Action Descriptors Click on all the buttons and the GUI should get updated with the information from the descriptors IY NXP LPC214x HID Example Vendor Mame NXP Semiconductors Product Name Keil hiCB2140 HID Serial Numer DEMO Interface HID INT1 not pressed MCB2140 Board detected Fig 27 GUI screenshot 2 The host is continuously polling the LPC2148 for an IN report every 8ms as set by the configuration wizard This further means that the HID lib will call GetlnReport void every 8 ms and enquire the user application if there is any data for the host GetInReport void is defined in the Blinky project Lets analyze the current GetIlnReport void function void GetInReport void if IOPINO amp PBINT 0 Check if PBINT is pressed InReport 0 0x01 else InReport 0 0x00 LO CO HT DD OF Aa WH LP Fe NXP B V 2008 All rights reserved Application note Rev 01 12 August 2008 24 of 35 NXP Semiconductors AN1 0736 LPC214x USB simplified InReport gets a 0 or a 1 depending upon the status of the INT1 button When this data arrives on the host side it is indicated to the Delphi application The application then goes and reads the data and changes the INT1 GUI element status accordingly Action IN Flow of Data Click on the INT1 button on the MCB2140 board and GUI should get updated wit
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