better comments.

enable interrupt later.
This commit is contained in:
nvt-se 2007-09-14 19:20:24 +00:00
parent ca733ddfce
commit 290f41db06

View File

@ -105,16 +105,16 @@ dma_transfer(unsigned char *buf, unsigned len)
* The source address is incremented for each byte, while the
* destination address remains constant.
*
* Important to use DMALEVEL when using USART TX
* interrupts so first edge
* doesn't get lost (hangs every 50. - 100. time)!
* In order to avoid missing the first rising edge of the trigger
* signal, it is important to use the level-sensitive trigger when
* using USART transfer interrupts.
*/
DMA0CTL = DMADT_0 | DMADSTINCR_0 | DMASRCINCR_3 | DMASBDB | DMALEVEL | DMAIE;
DMA0CTL = DMADT_0 | DMADSTINCR_0 | DMASRCINCR_3 | DMASBDB | DMALEVEL;
DMA0SA = (unsigned) buf;
DMA0DA = (unsigned) &TXBUF0;
DMA0SZ = len;
DMA0CTL |= DMAEN; // enable DMA
U0CTL &= ~SWRST; // enable UART state machine, starts transfer
DMA0CTL |= DMAEN | DMAIE; // enable DMA and interrupts
U0CTL &= ~SWRST; // enable UART state machine, starts transfer
}