SPI not functioning: LoPy NFC reader PN5XX case



  • Hello,

    I'm trying this for days now and I'm desperate. Can you help me ? Here is the problem. I'm trying to communicate with a PN532 board (http://puu.sh/wVkAH/f8804a6549.jpg) via a LoPy board with SPI.

    3.3v, GND, SCK(P10), MISO (P12), MOSI (P11) and SS(P9) are well connected on the LoPy board.

    I re-wrote some PN532 c/cpp/python libraries for micropython thanks to some pieces of code on forums (here is my code: https://pastebin.com/6h3fuWjF)

    Basically I'm starting a SPI connection (SPI.MASTER, baudrate=1000000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB)
    First thing, in all libraries I found they all use SPI.LSB but in pycom lopy doc there is ONLY MSB (screenshot of the doc: http://puu.sh/wVkJY/9cf5c92e48.png)

    Then to test the connection I'm checking the PN5xx firmware by sending a frame, I logged it:
    writeframe (decimal)
    TX: 1
    TX: 0
    TX: 0
    TX: 255
    TX: 2
    TX: 254
    TX: 212
    TX: 2
    TX: 42
    TX: 0
    end frame

    Then the PN5xx updates its register, when data are ready I'm supposed to make a "Status read" call by sending 0x02 to the PN5xx here is the log:

    Read status
    TX: 2
    RX: 0

    And that's my problem whatever I send I always get 0x00 data. Sometimes magically I receive 0x10(16) whatever frame I send. I thought it was coming from the MSB/LSB problem (0x10 => 0x01) and 0x01 is what I'm expected to get, but when I try to read the register I'm still getting 0x00

    I'm sure the PN5xx is working, I've tried to use an Arduino UNO + AdafruitPN532_SPI lib and it worked pretty well. I logged the frame, it's the same as mine with my python code but when it comes to Read status arduino uno gets a 0x01 response code. (And SPI.cpp lib is using firstbit=LSB)

    So 1st, why I can't use LSB instead of MSB on my LoPy and 2nd, Why I'm always getting error response from the PN5xx

    Thanks for help !

    (Btw, I'm writing this in one block just after 3 days of this thing which is driving me crazy sorry for my english)


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