Problems with NIOS II SPI communication

[Altera_Forum]

Hi, 

I'm using two DE0 board to communicate with SPI core. One configued as master and another as slave.  I tried to check spi status register to complement the slave code. And whole process is the master send data-- 0xabcd,and the slave receive the data and send back. But I found that the master can't receive the right data sometimes, less than 50% time the received data is right.  I run the master program with debug mode first and then run the slave one to avoid signal toggle on the slave's input side. I set SCLK from 128kHz to 1MHz,the problem is still there.   Here is my code for slave: int main(void) {  alt_u32 rddata=0x0;  alt_u32 status;  IOWR_ALTERA_AVALON_SPI_STATUS(SPI_BASE,0x0000);  IOWR_ALTERA_AVALON_SPI_TXDATA(SPI_BASE,0x1001);  IORD_ALTERA_AVALON_SPI_RXDATA(SPI_BASE);  while(1)  {  do  {  status = IORD_ALTERA_AVALON_SPI_STATUS(SPI_BASE);  }  while((status & ALTERA_AVALON_SPI_STATUS_RRDY_MSK)==0 &&  (status & ALTERA_AVALON_SPI_STATUS_RRDY_MSK) == 0);  rddata= IORD_ALTERA_AVALON_SPI_RXDATA(SPI_BASE);    IOWR_ALTERA_AVALON_SPI_TXDATA(SPI_BASE, rddata);  }    Code for master is : int main(void) {  void send(alt_u16 write);  alt_u16 receive();  alt_u16 wrdata=0xabcd;  alt_u16 rddata;  IOWR_ALTERA_AVALON_SPI_SLAVE_SEL(SPI_BASE, 1);  IORD_ALTERA_AVALON_SPI_RXDATA(SPI_BASE);  while(1)  {  send(wrdata);  rddata=receive();  }  return 0; } void send(alt_u16 write) {  alt_u32 status;  alt_u16 data;   IOWR_ALTERA_AVALON_SPI_CONTROL(SPI_BASE, 0x0400);  IORD_ALTERA_AVALON_SPI_RXDATA(SPI_BASE);  do  {  status = IORD_ALTERA_AVALON_SPI_STATUS(SPI_BASE);  }  while (((status & ALTERA_AVALON_SPI_STATUS_TRDY_MSK) == 0)&&  (status & ALTERA_AVALON_SPI_STATUS_RRDY_MSK) == 0);  IOWR_ALTERA_AVALON_SPI_TXDATA(SPI_BASE , write);  data=IORD_ALTERA_AVALON_SPI_RXDATA(SPI_BASE);  do  {  status = IORD_ALTERA_AVALON_SPI_STATUS(SPI_BASE);  }  while ((status & ALTERA_AVALON_SPI_STATUS_TMT_MSK) == 0);  IOWR_ALTERA_AVALON_SPI_CONTROL(SPI_BASE, 0); }  alt_u16 receive() {  alt_u16 data;  alt_u32 status;  IOWR_ALTERA_AVALON_SPI_CONTROL(SPI_BASE, 0x0400);  IORD_ALTERA_AVALON_SPI_RXDATA(SPI_BASE);  do  {  status = IORD_ALTERA_AVALON_SPI_STATUS(SPI_BASE);  }  while (((status & ALTERA_AVALON_SPI_STATUS_TRDY_MSK) == 0 ) &&  (status & ALTERA_AVALON_SPI_STATUS_RRDY_MSK) == 0);  IOWR_ALTERA_AVALON_SPI_TXDATA(SPI_BASE , 0x00);  data=IORD_ALTERA_AVALON_SPI_RXDATA(SPI_BASE);  do  {  status = IORD_ALTERA_AVALON_SPI_STATUS(SPI_BASE);  }  while ((status & ALTERA_AVALON_SPI_STATUS_TMT_MSK) == 0);  IOWR_ALTERA_AVALON_SPI_CONTROL(SPI_BASE, 0);  return data; }    Can anybody help on this problem? I think there maybe some mistake in my code. Has anybody use SPI core as a slave? Most people use the SPI core as a master, I really need some on the slave mode. Thank a lot!

[Altera_Forum]

hi truefrank,  

I checked your code and it is working fine for  DE2-115 board.