Service Manual
Contents
1. 20006 pote ogous WISS aus EST ams SEH aa RadioA_Mode Rx L _ Tx J Rx RadioA_SPI Hoas lees RF_Transmission_A PRD RadioB_Mode Tx Rx li IER RadioB_SPI Je Pktib Pki2b Figure 3 1 Timing Diagram RF_Transmission_B PkiOb The figure above describes the data path for two packets grey from radio A to radio B The mode signal indicates the state of each radio during each 750us time slot The payload for the two packets Pkt0a and Pktla to be transmitted is moved into the transceiver s internal buffer from the microcontroller att 0us 750us later the transceiver for radio A is transitioned to transmit mode and after a startup delay the two packets are transmitted At this time radio B will also be receive mode When the packets are decoded by radio B the payload is buffered in the transceiver until it can be read by the microcontroller at t 1 5ms This figure also shows that each packet is transmitted twice Pktla is first loaded into the transceiver of radio A at t 0s and again 1 5ms later All packets are identified by a 4 bit sequence number and by an additional bit that identifies a packet as a retransmission of a previous packet By checking these values the microcontroller is able to keep track of statistics such as the number of dropped packets which would be indi2. Sheet 2 4 Transceiver TITLE U3 Document Numbers REV Date 12 01 2002 098 11 44 Sheet 3 4 12 01 2007 08 14 03p C Program Files EAGLE 4 16r2 projects Senior Design V3 sch Sheet 3 4 12 01 2007 08 13 25p C Program Files EAGLE 4 16r2 projects Senior Design V3 sch Sheet 4 4 Power Subsystem TITLE U3 Document Numbers REU Date 12 01 2007 38 11 44p Sheet 4 4 Dec07 06 il 12 Kaerch a aS AZ I fis Figure 2 1 PCB Top Side Universal Communications Link 9 ba Ve Wl A 5 B lt t e Di BTA BTS BTS gt bi BS C I o 99 AA HT OS SH Dec07 06 This page intentionally left blank 14 Programming Universal Communications Link The Universal Communications Link is programmed through the JTAG connector located just below the LCD Sampling and Reconstruction Air Protocol Every 125 an interrupt is triggered by a hardware timer resulting in a sample rate of 8 kHz This interrupt samples the module s analog and digital inputs updates the analog and digital outputs and is responsible for all communication between the microcontroller and the transceiver IC The microcontroller s internal ADC has the capability to chain multiple conversion req
3. starts the debugger exit the debugger by pressing CTRL SHIFT D HABS 18 Universal Communications Link Testing The Universal Communications Link can be tested during assembly and after being programmed The following test procedure should be followed if the communications link does not perform as expected For testing procedure during assemble please refer to Chapter 3 Assembly section Assembly Procedure After Assembl The first stage of testing after assemble is to visually inspect the radio module for defects Some defects include bad PCB traces missing misaligned damaged components and poor no solder joints The visual inspection should catch most assembly errors A list of critical checkpoints can be found in the list below Damaged components Incorrect components PCB traces Missing components Misaligned components Solder joints et Ol 0 10 Hardware Testing The second stage of testing will be to verify individual components on the PCB are working properly Due to the scope of this project a large majority of hardware testing requires software being debugged however initial testing of all systems can be performed without software as follows Each of the following tests require at minimum a multimeter which is capable of measuring voltage and current and an oscilloscope which has a 1OMHz bandwidth All voltages are referenced to the ground GND test point on the PCB The radio module must
4. UNIVERSAL COMMUNICATIONS LINK SERVICE MANUAL Joseph Beierschmitt Shawn Freese Jared Leonard Matthew Raygor seg ee Universal Communications Link Contents About This Manual iii Related Doeume tati nnu u ii apa ua Hi Chapter 1 Introduction 5 Chapter 2 Assembly 7 E EE H AE e EANO i eae get ees 7 Assembly ee 7 Chapter 3 Programming 15 Sampling and Reconstruction cccccscccssecsseeseceeceecesecseceeecseeesececeseeeseeessecseecsaecsaecaeceseenseesereseeeenneeags 15 Air POLO COM cos ite ta kate vides iwan catus ee 15 Radio Svpnchron zapen 17 User ne fas ets 17 TEFET deb gger EE EE 17 Chapter 4 Testing 19 Atter Assembly 19 Hardware Testing aha ama 19 Functional Testing 20 5 Troubleshooting 23 Power SUDSY SUSI m Aids 23 Usd 23 Microcontroller nern eier 24 Transceiver energie nn neben 24 Dec07 06 This page intentionally left blank Universal Communications Link About This Manual This manual contains information for assembling and testing the communications link developed by the ECE senior design team Dec0706 This manual requires that you have a basic understanding of interrupting schematics and are proficient in soldering a printed circuit
5. bleshooting power subsystem of this section 2 Verify pin 2 of LCD is within the range of 0 to 0 01V referenced to GND test pad 3 Verify pin 3 of LCD is within range of 0 to 1V referenced to GND test pad if not replace component US level translator 4 Verify pin 6 of LCD is pulsing if not refer to troubleshooting Microcontroller of this section 5 Verify pins 7 14 of LCD is pulsing after a button pressed if not refer to troubleshooting Microcontroller of this section 2992 Dec07 06 Microcontroller Transceiver Check that the pins of the MCU are connected correctly see PCB schematic in this manual Check that the MCU has a voltage input level of approximately 3 3V Check the MCU clock pin 57 to ensure the clock is running properly Check that the MCU is properly programmed with the JTAG connector if the doesn t communicate with the MCU a possible replacement of MCU is needed Check the pins of the transceiver chip are connected correctly see PCB schematic in this manual Check that the transceiver chip has a voltage input level of approximately 3 3V Check to see if the transceiver output pins to see if the chip can communicate with another working radio using a spectrum analyzer 24 Universal Communications Link Notes CH Dec07 06 Notes 26
6. board Related Documentation The following documents contain information that you might find helpful as you use the communications link e The Universal Communications Link final report e The Universal Communications User Manual The following resources contain information about concepts and products related to the communications link nRF24L01 Single Chip 2 4GHz Transceiver MSP430x16x Mixed Signal Microcontroller Hi Dec07 06 This page intentionally left blank Universal Communications Link Introduction The Universal Communications Link was developed as a short range 2 way wireless data link for other senior design teams use The communications link contains components for handling user s data input buffering incoming RF data while sending outgoing RF data and servicing user s commands through an interface The dynamic system shown in Figure 1 1 refers to the combination of the user and the communications link Communications Link User s Data Microcontroller User Interface Transceiver Figure 1 1 Dynamic System The dynamic system in Figure 1 1 represents a 2 way communication system In operation user s data is received from the adjacent link and transmitted to the adjacent link at the same time Dec07 06 This page intentionally left blank Universal Communications Link Assembly The Universal Communications Link can be assembled by hand using a soldering i
7. cated by a gap in sequence numbers between packets The signal strength indicator on the home screen on the LCD is calculated from the number of dropped packets Byte Name Description 0 ACK information Bits 7 5 Reserved for future use Bit4 Acknowledge enable 1 or disable 0 Bits 3 0 Sequence number of last packet from other radio to acknowledge 1 Packet Header Bits 7 6 Packet type default 00 Reserved for future use Bit4 Original transmission 1 or retransmission 0 Bits 3 0 Sequence number 2 13 Analog 0 Data Twelve bytes of data from analog input 0 8 bit wide samples first sample first 14 25 Analog 1 Data Twelve bytes of data from analog input 1 8 bit wide samples first sample first 26 31 Digital Data Six bytes of data from digital inputs 4 bits per sample two samples per byte Byte 0 Bits 3 0 Sample 0 Byte 0 Bits 7 4 Sample 1 Byte 1 Bits 3 0 Sample 2 Byte 5 Bits 7 4 Sample 11 Figure 3 2 Payload Description 16 Universal Communications Link The table above describes the format of a packet s payload as seen by the microcontroller In addition to this payload the transceiver IC appends a 16 CRC and an 11 bit address If a packet is received by a transceiver and the address does not match or the CRC fails the packet will be discarded automatically Every packet contains 32 bytes of payload 30 bytes of which are used to store a
8. have access to power either through the batteries or DC power unless otherwise noted This stage of testing will only be implemented on the prototype design however if the end product design does not pass the functionality testing these checklists shall be implemented to locate the problem Microcontroller Checklist Voltage measured between the microcontroller pins 1 25 58 and the test ground pad must be within the range of 3 27 and 3 33V 19 Dec07 06 Voltage measured between the microcontroller pins 11 52 62 63 and the test ground pad must not exceed 0 03V 8 MHz clock measured between pins 8 and 9 must be present and operating within 5 of 8 MHz User Interface Checklist Voltage measured between the microcontroller pins 13 14 15 16 and the test ground pad must be within the range of 3 27 and 3 33V when the corresponding button is pressed The settling time of each button must reach a stable response within 750 us If this does not happen the tactile switch may need replacement Voltage measured between the LCD pin 1 and the test ground must be with the range of 3 27 and 3 33V Voltage measured between the LCD pin 2 and the test ground must not exceed 0 03V Voltage measured between the LCD pin 4 and the test ground should be within the range of 0 to 1V Dependent upon LCD contrast Power Subsystem Checklist When the external DC power source is not present the internal batteries p
9. is test is to measure the current that the radio module is using when it is in its sleep and transmit receive modes as well as check the power switchover time from external to internal power These measurements are done with the help of a multimeter and are recorded These values should not exceed the specifications define by the project team User Interface Test This test is to perform regression testing of the interface verify that the LCD is contrasted correctly and clearly seen and to check that the non volatile memory of the LCD works Regression testing is done to check newly implemented software that previously worked as desired but has stop working or no longer works in the same way as seen in previous versions of the code The readability of the LCD is visually inspected and adjusted as needed The non volatile memory of the LCD is checked by selecting different channel and power configurations other than the default settings These settings should then be displayed by the LCD in the home screen If the radio module is powered off and later powered back on the LCD should still display these same values and not reset to the default configurations Waveform validation This test is to measure the comer frequencies of the analog filters and verify the signal integrity from the input of one radio module to the output of another An oscilloscope is used to confirm that the signal seen on the input pin of the first radio matches with the out
10. nalog and digital samples This is enough to store 12 samples worth of data 2 8 bit analog channels 4 1 bit digital channels The acknowledge information is not currently used but was included for future expansion Radio Synchronization User Interface In order for the radios to communicate the transmission time slots between the two radios must be synchronized If the 750us transmission time slots overlap by more than 40us the link will fail After initial power up the radios enter a search state where they listen for a packet from another radio to synchronize with Instead transmitting packets every 1 5ms when a radio is in search mode it transmits a packet every 23 25ms and spends the rest of the time in receive mode Every time a radio decodes a valid packet an interrupt is thrown from the transceiver to the microcontroller When this occurs the microcontroller reads an internal timer and compares the time the packet was received to the time the microcontroller expected to receive the packet The microcontroller then sums the error from the last sixteen received packets If this error is too high the microcontroller s timer is reset to resynchronize the radios The transmission timing for the radio is derived from this timer by changing it value the time until the next transmission time slot can be adjusted as well The user interface for the radio module consists of a character LCD and four tactile switches Through these the use
11. put pin of the second User Test This test is to have the client use the radio modules with only the help of the user manual to guide them Successful results will ensure that the user manual does explain correctly and clearly on how to operate the radio modules If the client encounters problems using the modules the user manual will be adjusted accordingly 21 Universal Communications Link Troubleshooting Power subsystem The section is intended to aid the user in troubleshooting the communications link User Interface External DC power source not present internal batteries present 1 Voltage on pin 1 of Texas Instruments TPS78833 voltage regulator should be within range of 3 6 and 4 5V if not replace component U1 dual P channel FET 2 Voltage of pin 5 of Texas Instruments TPS78833 voltage regulator should be within range of 2 9 and 3 3V if not replace component U2 voltage regulator External DC power source present internal batteries not present 1 Voltage on pin 1 of Texas Instruments TPS78833 voltage regulator should be within range of 3 6 and 10V referenced to GND test pad if not replace component D13 Schottky diode 2 Voltage of pin 5 of Texas Instruments TPS78833 voltage regulator should be within range of 2 9 and 3 3V if not replace component U2 voltage regulator LCD does not display 1 Verify pin 1 of LCD is within the range of 3 27 to 3 33V referenced to GND test pad if not refer to trou
12. r is able to select the radios frequency transmit power and is able to place the module into a sleep state All UI processing takes place in the program main thread An infinite loop continuously checks the state of the push buttons and refreshes the LCD when necessary When the channel or transmit power are changed by the user flags are set to inform the sampling ISR to reconfigure the radio The radio is not directly configured in the main thread to prevent resource conflicts TI FET debugger or equivalent New firmware may be downloaded to the MSP430 microcontroller using a TI FET or equivalent adaptor and the Embedded Dec07 06 Workbench software An evaluation copy of Embedded Work bench is available at http supp iar com Download S W item EW430 EVAL Since the current firmware image is greater than 4kb the evaluation or the fully licensed version of Embedded Workbench is required The Kickstart edition will not work To download firmware onto the MSP430 1 Open Embedded Workbench 2 Connect the JTAG interface to the computers Parallel port and to the radio module Power the radio module using either batteries or an AC adaptor On the Workbench menu bar click File gt Open gt Workspace Locate the project folder and select Cpre491_new eww After the project has loaded the firmware image can be downloaded by pressing CTRL D 7 This key sequence downloads the firmware image and
13. ron It is recommended that the user be familiar with soldering surface mount Some difficulty may be encountered when soldering the transceiver integrated chip Schematics The schematics were created using Cadsoft Eagle version 4 16 and can be viewed on the following pages PCB Artwork The PCB artwork was created using Cadsoft Eagle version 4 16 and can be seen in Figure 2 2 and Figure 2 1 Assembly Procedure It is recommended to assemble the communications link in this order Reflow nRF24L01 transceiver IC Solder 0402 components Solder power subsystem circuitry Test supply current should not exceed 15mA Solder msp430f167 microcontroller IC Test supply current should not exceed 15mA Solder remaining IC Solder 0805 components Solder tactile switches and remaining components Test supply current should not exceed 20mA 10 0 OI Er Er O Signal Processing d i I TITLE U3 Ba Document Number REV Date 12 01 2007 98 07 45p Sheet 1 4 12 01 2007 08 08 14p C Program Files EAGLE 4 16r2 projects Senior Design V3 sch Sheet 1 4 ER A BEES gee 7 BA Z Microcontroller 12 01 2007 08 12 40p C Program Files EAGLE 4 16r2 projects Senior Design V3 sch Sheet 2 4 TITLE V3 REU Document Number Date 12 01 2007 08 11 44
14. rovide power to the circuitry therefore should be within the range of 3 6 and 4 5V depending upon the charge on the batteries When the external DC power source is present the external source provides power to the circuitry therefore should be within the range of 5 and 10V depended upon the source Irregardless of the power source present the voltage measured between the voltage out test point and the ground test point must be within the range of 3 27 and 3 33V Battery current lt 10 uA test may be omitted due to the fact the current measurement must be made in series with the batteries which means the batteries must be accessed during this test Transceiver Checklist Voltage measured between pin 1 of 1 5 and the test ground pad must be within the range of 3 27 and 3 33V Voltage measured between pin 8 of PJ5 and the test ground pad must not exceed 0 03V Functional Testing Range Test This test is to measure the number of RF packets lost digital amp analog data over a one second time period The radio modules are placed in an open field and are in line of sight of one another The distance between the radio modules is slowly walked off as the number of RF packets lost is measured Once the number of drop packets has become great enough as to cause the radio modules to cease communication with each other the distance between them is measured and the range recorded 20 Universal Communications Link Power Test Th
15. uests together so that they are initiated by a single trigger Using this feature the ISR can read the results from the previous ADC conversions immediately instead of having to initiate four analog input 1 analog input 2 battery voltage and temperature conversions independently and wait for them to finish After reading the conversion results the next series of conversions is initiated and the ISR continues without blocking The transceiver supports three modes transmit receive and standby While in transmit or standby mode the transceiver is unable to decode incoming packets To account for this time slot synchronization is used to synchronize transmission times between two radios In each 1 5ms period 750us are allocated to each radio to transmit Since the radios operate in the 2 4GHz band the protocol must tolerate Bluetooth traffic Bluetooth devices frequency hop between packet transmissions meaning that Bluetooth traffic may collide with traffic from the radio modules To improve its tolerance to these collisions as well as to add a level of data redundancy the air protocol transmits each packet twice The retransmission always occurs during the next transmission time slot or approximately 1 5ms later Bluetooth packets may last up to 850us after which the device will hop to another frequency Delaying the retransmission longer than this improves the chances of the packet reaching its destination 15 Dec07 06
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