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Original question:

TMs570 SPI Reception - Compatibility mode

TMS570LC4357: HI-3593 response message

Alex Duranti
Prodigy 191 points
Part Number: TMS570LC4357


Good morning,

I'm experimenting with TMS570LC4357 microcontoller to communicate with HI-3593 Holt for ARINC-429  data transfer.

I've an issue: 

I transmit on arinc the following 32 bit message: 0x12345678

On the Holt receiver i send the op-code followed by 4 byte but i read back the following message: 0xFF123456.

 

I execute a dummy write on SPIDAT1 as required, but the first byte is 0xFF.

(If i not execute the dummy write the message response wil be: 0xFFFF1234)

Thanks

Alex

  • 0
    TI__Guru**** 197546 points

    Hi Alex,

    Alex Duranti said:
    I execute a dummy write on SPIDAT1 as required, but the first byte is 0xFF.

    Since HI-3593 command byte instruction, reception is half-duplex, the SPI host discards the dummy byte it receives while serially transmitting the command byte.

    From TMS570 (host) size, you need to transfer 5 bytes, the 1st byte is the command or opcode to HI-3593, the 2nd to 5th bytes are the dummy bytes.

  • 0 in reply to QJ Wang
    Prodigy 191 points

    Thanks QJ,

    I explain more in detail the HI-3593 unexpected behaviour:

    - I enable the self test on Holt device: (command: 0x0830)

    - I send the following test message to the Holt TX (0x0C12345678)  -->op code + 4 data bytes

    - i read the message on Holt RX FIFO (0xA000000000) -->op code + 4 dummy bytes

    The message that i read on SPI is: 0xFFFF123456

    It seems that there are 2 dummy bytes on the received response