// 8 bits per transfer, no loopback, MSB first, 1 transfer per sync
// pulse, no output sync, start on positive-going edge of sync
- AT91C_BASE_SSC->SSC_RFMR = SSC_FRAME_MODE_BITS_IN_WORD(8) |
- AT91C_SSC_MSBF | SSC_FRAME_MODE_WORDS_PER_TRANSFER(0);
+ AT91C_BASE_SSC->SSC_RFMR = SSC_FRAME_MODE_BITS_IN_WORD(8) | AT91C_SSC_MSBF | SSC_FRAME_MODE_WORDS_PER_TRANSFER(0);
// clock comes from TK pin, no clock output, outputs change on falling
- // edge of TK, start on rising edge of TF
- AT91C_BASE_SSC->SSC_TCMR = SSC_CLOCK_MODE_SELECT(2) |
- SSC_CLOCK_MODE_START(5);
+ // edge of TK, sample on rising edge of TK
+ AT91C_BASE_SSC->SSC_TCMR = SSC_CLOCK_MODE_SELECT(2) | SSC_CLOCK_MODE_START(5);
// tx framing is the same as the rx framing
AT91C_BASE_SSC->SSC_TFMR = AT91C_BASE_SSC->SSC_RFMR;
// ourselves, not to another buffer). The stuff to manipulate those buffers
// is in apps.h, because it should be inlined, for speed.
//-----------------------------------------------------------------------------
-void FpgaSetupSscDma(uint8_t *buf, int len)
+bool FpgaSetupSscDma(uint8_t *buf, int len)
{
- AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
-
- AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t) buf;
- AT91C_BASE_PDC_SSC->PDC_RCR = len;
- AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) buf;
- AT91C_BASE_PDC_SSC->PDC_RNCR = len;
-
- if (buf != NULL) {
- AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTEN;
- }
+ if (buf == NULL) {
+ return false;
+ }
+
+ AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS; // Disable DMA Transfer
+ AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t) buf; // transfer to this memory address
+ AT91C_BASE_PDC_SSC->PDC_RCR = len; // transfer this many bytes
+ AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) buf; // next transfer to same memory address
+ AT91C_BASE_PDC_SSC->PDC_RNCR = len; // ... with same number of bytes
+ AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTEN; // go!
+
+ return true;
}
static void DownloadFPGA_byte(unsigned char w)