Posted on September 21, 2011 at 00:02Hi all,
I am working a project that has a SPI master on an OMAP-L138. I had the four lines manually wired across from the OMAP-L138 to the STM8-S discovery board. The connections are below:
OMAP SPI CS -> STM8 SPI NSS
OMAP SPI SCLK -> STM8 SPI CLK
OMAP SPI MOSI -> STM8 SPI MOSI
OMAP SPi MISO -> STM8 SPI MISO
This is my initialization function of the SPI as a slave.
static void enable_spi_slave(void)
{
SPI_DeInit();
SPI_Init(SPI_FIRSTBIT_MSB,
SPI_BAUDRATEPRESCALER_8,
SPI_MODE_SLAVE,
SPI_CLOCKPOLARITY_LOW,
SPI_CLOCKPHASE_1EDGE,
SPI_DATADIRECTION_2LINES_FULLDUPLEX,
SPI_NSS_HARD,
0x07);
SPI_Cmd(ENABLE);
}
void main(void)
{
u8 command;
u8 *ptr;
enable_spi_slave();
while(1) {
u8 i=0;
//read_power_amp_status();
//update_ready_status_for_arm();
//while((GPIOE->IDR & 0x20) == 0x00);
if(SPI_GetFlagStatus(SPI_FLAG_RXNE) == SET) {
command = SPI_ReceiveData();
switch(command) {
case PTT_POWER_AMP_GET_STATUS:
{
/*
Write the statuses back to the SPI master.
*/
//for(i=0; i<27; i++) SPI_ReceiveData();
//SPI_ReceiveData();
bufptr = buffer;
for(i=0; i<12; i++) {
//while(SPI_GetFlagStatus(SPI_FLAG_TXE) != SET)
while((GPIOE->IDR &0x20) == 0x00)
{
if((SPI->SR & SPI_FLAG_TXE) == SPI_FLAG_TXE) {
SPI->DR = (u8)0x0d;
SPI->DR = (u8)buffer[i];
//SPI_SendData(buffer[i]);
//bufptr++;
}
}
//SPI_ReceiveData();
}
//SPI_SendData(0x00);
SPI_ReceiveData();
}
break;
default:
{
while((GPIOE->IDR &0x20) == 00) ;
SPI_ReceiveData();
}
break;
}
}
//delay(50);
}
}
Basically, on the OMAP side I send over 0x1 followed by 12 zeros. I can see that the 0x1 came over the wire on MOSI, which is my command (PTT_POWER_AMP_GET_STATUS). I want to write back 12 bytes and that is main problem. I constantly received 0x3a or 0x38. What i sent back is 0xd 0xe 0xa 0xd repeated 3 times. And on the scope, the signal for MISO is not what I expect. Has anyone seen this problem using the SPI slave on the STM8 Discovery?
Any advice or comments is appreciated.
Thanks,
Tom
#stm8s-discovery
