Data transfer from SAI to DTCM using HPDMA not working

[nige_w]

I am using a Nucleo-N657X0-Q board to prototype a data collection system that collects samples from an ADC connected to the SAI peripheral and places the results in RAM. If I use CPU AXI RAM0 as the destination this works correctly, but if I change the destination to DTCM all I get is a buffer full of zeroes.

According to chapter-17 of the ref manual, HPDMA1 AXI port has access to the DTCM and I am setting the DAP field of HPDMA-CH0 TR1 register to Port-0 as required (setting it wrong results in a DTEF interrupt).

I have RISAF 1 and RISAF 2 set as follows:

  RISAF1->REG[0].CFGR    = 0x00000000;
  RISAF1->REG[0].CIDCFGR = 0x00FF00FF; /* RW for everyone */
  RISAF1->REG[0].STARTR  = 0;
  RISAF1->REG[0].ENDR    = 0xFFFFFFFF; /* all-encompassing */
  RISAF1->REG[0].CFGR    = 0x00000101; /* enabled, secure, unprivileged for everyone */

  RISAF2->REG[0].CFGR    = 0x00000000;
  RISAF2->REG[0].CIDCFGR = 0x00FF00FF; /* RW for everyone */
  RISAF2->REG[0].STARTR  = 0;
  RISAF2->REG[0].ENDR    = 0xFFFFFFFF; /* all-encompassing */
  RISAF2->REG[0].CFGR    = 0x00000101; /* enabled, secure, unprivileged for everyone */

I have the channel 0 bits in both HPDMA_PRIVCFGR and HPDMA_SECCFGR set.

I also have added the following to the reset handler and can read and write to DTCM OK using the CPU.

  ldr   r0, =0x30000000
  ldr   r1, =0x30020000
  mov	r2,#0
clear_dtcm:
  str   r2,[r0]
  add   r0,r0,#4
  cmp   r0,r1
  bcc   clear_dtcm  

The program is a secure domain only application.

Can anyone think of any other reason why this is not working?

Thanks

Nige