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TRF7970A: SDM transmission issue

Part Number: TRF7970A
Other Parts Discussed in Thread: MSP430F2370

Hi,

We are using sloa214 Application code as base code for our boar with MSP430F2370 TRF7970A and our board is similar to TRF7970A EVM in terms of GPIO assignment.

In case of SDM trasmission in Auth1 MSP430F2370 should be sending 4 byte.

0x60 , 0x04, CRC_1, CRC_2 

so it should be below binary form with parity bit for first 2 byte

000001101 001000000

but when RFID card Auth fails on logic analyzer we are observing following data. It is geting shifted to the right.  
0000001101 001000000

See attached waveform or open attached Logicport session (can be viewed in https://www.pctestinstruments.com/downloads.htm) for more detail.

On same board some time cards works perfectly fine with reduced range. what could be possible reason. LogicPort_MSP430F2370_TRF7970A.rar

  

  • Hello Hardik,

    That is not behavior we have seen before. Is this occurring on only one unit? How many units have you tested at this point? Can you give numbers of pass vs fail?

    Also along with that, if you can provide the site & lot code information for the device, we can look into the history of material you received. You can either send a screenshot of the device with the markings displayed or record the 7 digit information, see this for what is relevant: https://www.ti.com/lit/pdf/sloz011

    Also to better understand your system can you provide the following:

    1) Are you running in 3V mode or 5V mode?

    2) What are your Regulator Control settings?

    3) Are you following the startup sequence outlined in the device datasheet?

  • Hi,

    We have TRF 7970A TI 8CK AHXP G4 marking on chip.

    Out of 1000 board we have nearly 100 boards which not working properly. We have captured this signal in one faulty board do you want to test this in more boards.

    Out of 100 some of working with very low range for example in my main question the board I used for test from 100 faulty board If I place RFID card on antenna it works every time but when I  create gap between antenna and rfid card about 10 mm it pass mifare classic auth only by many retries takes 4-5 seconds card read retries at every 200ms. So this waveform is from fail case where auth1 fails but as said earlier if I place RFID tag on antenna without any gap it works every time. 

    Some other board do not detect RFID card even if we place directly on antenna. For your information other perfectly working fine board detects RFID card at arround 40-50mm distance form antenna and RFID card.

    Also to better understand your system can you provide the following:

    1) Are you running in 3V mode or 5V mode?

    Ans: Board is at 3V  this waveform captured when board with 3V. For test as we have provision for 5V in hardware we tested it for 5V but performance is not improved in faulty boards.   

    2) What are your Regulator Control settings?

    Ans: Code is based on sloa214 application note nothing changed other than LED indication and retry on card read failure and some other application logic.

    3) Are you following the startup sequence outlined in the device datasheet?

    Ans: Code is based on sloa214 application note nothing changed other than LED indication and retry on card read failure and some other application logic.

    If require we can share code in private to you let me know so I can get permission for the same.

    Regards,

    Hardik Harpal

     

  • Hello Hardik,

    Sorry for delay in reply here.

    Thanks for the screenshots, the issue is very clear to see and when compared to my own screenshots, I do see that extra bit clearly on yours.

    What I don't understand fully is the range dependence. Are you seeing the extra bit not transmit when some tags are brought in close range? And that the range to the tag is influencing if that extra bit is output?

    hardik harpal said:
    Ans: Board is at 3V  this waveform captured when board with 3V. For test as we have provision for 5V in hardware we tested it for 5V but performance is not improved in faulty boards.   

    Are you setting the 5V setting when doing this? Or are you sourcing 5V but leaving the device configured for 3V operation? If you are sourcing 5V you need to change the software to be running in 5V mode as well. I would like to understand your test results with both 5V sources and 5V setting applied.

    hardik harpal said:
    Ans: Code is based on sloa214 application note nothing changed other than LED indication and retry on card read failure and some other application logic.

     

    I see, okay so that would mean that Regulator Control is running in Automatic mode. I would recommend doing manual setting for your board based on your input voltage. If you are really at 3V input then I would say you need to use a setting of Regulator Control = 0x04 at highest. You can also try 0x00. See if either of these help.

    hardik harpal said:
    If require we can share code in private to you let me know so I can get permission for the same.

    I'm not too worried about the code, but what I really would need to see next is the schematic to check for any issues there. I will send you an E2E friend request so you can share the schematic privately.

    Edit By the way...

    hardik harpal said:
    We have TRF 7970A TI 8CK AHXP G4 marking on chip.

    That did not pull up a result for me, can you send a picture of the IC so I can make sure the LTC is right in order to check into the history of that silicon batch? You can private message me that as well if you need.

  • Thanks for reply.

    I will do more test and let you know better understanding on this issue.

    But in mean time can you help me with another issue facing in same project. you can find detail about this issue here https://e2e.ti.com/support/microcontrollers/msp430/f/166/t/927536   basically as card fails I have added retries so atleast after few retries it may able to read card. In this when card fails to authenticate some time code jumps to ISR trap to find out what ISR generated I written down all possible ISR handler even that ISR is not enabled in code so after running test I found out that TimerB1 INT is getting triggered. I am sharing test code with you in private message for better understanding.

    Regards,

    Hardik Harpal    

  • Hello Hardik,

    Unfortunately I don't have the MSP430 knowledge to help. I can say the libraries would not set those flags, they only include proprietary algorithms for Mifare, nothing to do with timers.

    I asked the team who handles those questions to look into for you so you should be getting a reply from a TI employee (if you haven't yet).

    You may also want to post as well with latest details.