AM2432: SORTE_G, How to use CRC module

Hi Shimizu-san,

SORTE_G uses the standard CRC hardware of ICSS. Please refer to the AM243x TRM, section "PRU_ICSSG MII_G_RT Module".

For IOEX receive in device, we use RX L2 method: See TRM section "RX MII Port → RX L1 FIFO → RX L2 Buffer → PRU"

We identify the last location of the receive byte, and then check bit 7 (ERROR_CRC) of the received frame, which resides somewhere between R10 to R13 called Status Registers. This makes sense when you read the TRM.

The location in ioex_g.asm where the check is done is here.

; Check CRC
; 2 bytes of data are merged into one byte of status
lsr R1.b0, R1.b0, 1
; add offset to R10
add R1.b0, R1.b0, (10*4)
mvib TEMP_REG_1.b0, *R1.b0
qbbs IOEX_FWD_EOF_CRC_ERROR, TEMP_REG_1.b0, L2_ERROR_CRC_FLAG_BITNUM

I hope this answers your question.

Regards,

 Thomas