RM48 - spiTransmitData from spi.c

Hi user4544371,

The reason is that the TX Ready flag is set as soon as the transfer starts.. the SPI is double buffered.
But the function is written to block until the transmission ends, and it reads the SPI buf after the transmission to
avoid having the overrun error flag set.

That's why it's checking for the receive flag instead of the transmit at the end. the next line reads the receive data
to avoid overflow

while((spi->FLG & 0x00000100U) != 0x00000100U)
{
} /* Wait */
SpiBuf = spi->BUF; <<< cannot do this, until receive data is ready.

-Anthony

Hello Anthony,

First thanks for this reply!

Regarding while loop, does it mean that I have to use SPI in a special way (like programming slave to send back ack or something like that)? My program is systematically blocked in this loop because no data received...

Regarding spiBuf, this variable is local and linked to...nothing... I conclude that it is useless.

Below is the code from spi.c:

uint32 spiTransmitData(spiBASE_t *spi, spiDAT1_t *dataconfig_t, uint32 blocksize, uint16 * srcbuff)
{
volatile uint32 SpiBuf;
uint16 Tx_Data;
uint32 Chip_Select_Hold = (dataconfig_t->CS_HOLD) ? 0x10000000U : 0U;
uint32 WDelay = (dataconfig_t->WDEL) ? 0x04000000U : 0U;
SPIDATAFMT_t DataFormat = dataconfig_t->DFSEL;
uint8 ChipSelect = dataconfig_t->CSNR;

/* USER CODE BEGIN (10) */
/* USER CODE END */

while(blocksize != 0U)
{
if((spi->FLG & 0x000000FFU) !=0U)
{
break;
}

if(blocksize == 1U)
{
Chip_Select_Hold = 0U;
}
/*SAFETYMCUSW 45 D MR:21.1 <APPROVED> "Valid non NULL input parameters are only allowed in this driver" */
Tx_Data = *srcbuff;

spi->DAT1 = ((uint32)DataFormat << 24U) |
((uint32)ChipSelect << 16U) |
(WDelay) |
(Chip_Select_Hold) |
(uint32)Tx_Data;

/*SAFETYMCUSW 567 S MR:17.1,17.4 <APPROVED> "Pointer increment needed" */
srcbuff++;

/*SAFETYMCUSW 28 D MR:NA <APPROVED> "Hardware status bit read check" */
while((spi->FLG & 0x00000100U) != 0x00000100U)
{
} /* Wait */

SpiBuf = spi->BUF;

blocksize--;
}

/* USER CODE BEGIN (11) */
/* USER CODE END */

return (spi->FLG & 0xFFU);
}

Many thanks for your help!

Frederic

Frederic,

user4544371 said:

Regarding while loop, does it mean that I have to use SPI in a special way (like programming slave to send back ack or something like that)? My program is systematically blocked in this loop because no data received...

There isn't any sort of ACK and you don't even need to have a slave send anything back for this example.

user4544371 said:

Regarding spiBuf, this variable is local and linked to...nothing... I conclude that it is useless.

The data is discarded in this function - yes - because it is a transmit only function.

But the SPI always transmits and receives at the same time.  

The act of reading spi->BUF clears the RX full status - preventing an overrun error from occurring if you call the transmit function again.

Try commenting out the read of spi->BUF and you'll see that after a few calls to spiTransmitData- you will have the receive overrun error flag set.

Hello Anthony,

Ok, issue solved...

I first configured SOMI as normal IO because not used in my design... So the SPI block did not detect message reception in parallel with emission.

In parallel, please note that HalcoGen bugs on SPI1SOMI[0] configuration... Here are all the details I can give:

Halcogen 04.05.02

Issue: In MIBSPI1 - MIBSPI1Port - SOMI[0] Pin mode setting => A configuration on this pin seems to have no effect on spiREG1->PC0.

 spiREG1->PC0  =   (uint32)((uint32)1U << 0U)  /* SCS[0] */
                    | (uint32)((uint32)1U << 1U)  /* SCS[1] */
                    | (uint32)((uint32)1U << 2U)  /* SCS[2] */
                    | (uint32)((uint32)0U << 3U)  /* SCS[3] */
                    | (uint32)((uint32)0U << 4U)  /* SCS[4] */
                    | (uint32)((uint32)0U << 5U)  /* SCS[5] */
                    | (uint32)((uint32)0U << 8U)  /* ENA */
                    | (uint32)((uint32)1U << 9U)  /* CLK */
                    | (uint32)((uint32)1U << 10U)  /* SIMO[0] */
                    | (uint32)((uint32)0U << 11U)  /* SOMI[0] */
                    | (uint32)((uint32)0U << 17U)  /* SIMO[1] */
                    | (uint32)((uint32)0U << 25U); /* SOMI[1] */

The line /*SOMI[0] */ never goes to 1 so SOMI[0] is not activated...

Setting manually this bit to 1 solve my issue.

Thanks Anthony for your help