Texas Instruments TMS320DM357 manual Industry Standards Compliance Statement

Introduction www.ti.com

Example 4. Programming the USB DMA Controller (continued)

//Increment descriptor counter tx_desc[ch]++;

}

//Routine to start the RX DMA for a given channel void start_rx_dma(int ch) {

int index_save;

index_save = usbRegs->INDEX; // Save the index to restore later

//Must have at least 3 descriptors to receive anything if (rx_desc[ch] < 2) {error++;} else {

usbRegs->INDEX = ch+1; usbRegs->RCPPICR = 1; //Enable Rx CPPI DMA

usbRegs->CHANNEL[ch].RCPPIDMASTATEW1 = (Uint32)(&rx_bufferDesc[ch][0]); CSL_FINS(usbRegs->PERI_RXCSR,USB_PERI_RXCSR_DMAEN,1);

//Update the buffer count register. This ADDS to the existing value, does not

overwrite.

switch (ch) {

case 0: usbRegs->RBUFCNT0 = rx_desc[ch]; break;

case 1: usbRegs->RBUFCNT1 = rx_desc[ch]; break;

case 2: usbRegs->RBUFCNT2 = rx_desc[ch]; break;

case 3: usbRegs->RBUFCNT3 = rx_desc[ch]; break;

}
}
usbRegs->INDEX = index_save;	// Restore the index to previous value
}

//Function to build Rx DMA descriptors
void add_rx_descriptor(int ch, unsigned char *		outBuf, int bytes) {
int index_save;
index_save = usbRegs->INDEX;	//	Save the index to restore later

if (bytes < 1) {bytes = 64; error++;} usbRegs->INDEX = ch+1;

//Link previous buffer to this one if this is not the first descriptor of the channel if (rx_desc[ch] > 0) rx_bufferDesc[ch][4*(rx_desc[ch]-1)] =

(Uint32)(&rx_bufferDesc[ch][4*rx_desc[ch]]);

rx_bufferDesc[ch][4*rx_desc[ch]+0] = (Uint32)(0x00000000);		// Next descriptor
rx_bufferDesc[ch][4*rx_desc[ch]+1] = (Uint32)outBuf;		// Buffer address
rx_bufferDesc[ch][4*rx_desc[ch]+2] = (0x0000 << 16) bytes;		// Rx buffer size in bytes
rx_bufferDesc[ch][4*rx_desc[ch]+3] = OWNER 0;		// OWNER
rx_desc[ch]++;
usbRegs->INDEX = index_save;	// Restore the index to previous value

}

1.6Industry Standard(s) Compliance Statement

This device conforms to USB 2.0 Specification and On-The-Go Supplement to the USB 2.0 Specification Rev 1.0a.

22 Universal Serial Bus (USB) Controller SPRUGH3–November 2008

Submit Documentation Feedback