MSP430F5659 DMA for transmitting via UART

As shown in figure 11-3, after DMAEN=0, the next transfer will restart from the beginning of the buffer.

Table 11-2 shows that TXIFG does not trigger a transfer if TXIE is set. So you could enable the interrupt to pause DMA.

As shown in figure 11-3, after DMAEN=0, the next transfer will restart from the beginning of the buffer.

[Itsik] - As I see, the size is not reset. I can use it for calculate the location of the next bytes to send - correct?

Table 11-2 shows that TXIFG does not trigger a transfer if TXIE is set. So you could enable the interrupt to pause DMA.

[Itsik] - Yes, but I will have to deal with interrupt handler because it is not promise that I will success to reset the TXIFG after setting the TXIE before the interrupt handler will called. So it looks like little tricky.

If the 1st solution is acceptable I prefer it.

As shown in figure 11-3, the size is reset.

When byte is sent, according to the button state, the register is decremented (Decrement DMAxSZ) and not the local variable (T_Size).

When the DMAEN is reset, the leftmost arrow takes me to the 'Reset' state (Is this state is reset the size register?) then setting back the DMAEN the (DMAxSZ -->T_Size ) register is setting the local value.

So where the size register is reset if the DMA is disabled?

Quota from datasheet:

DMAEN is automatically cleared when DMAxSZ transfers have been made.

According to the datasheet, the DMAEN is reset when the size arrived to zero and not the opposite direction.

For sum up:

Suspend will be implemented by DMAEN = 0;

Resume will be implemented by:

1) calculating the source address using the DMAxSZ value.

2) DMAEN = 1;

3) DMAxSZ with no change.

Can you confirm?