TMS320F28027F: SCI Functionality Questions

Garrett,

1. How to use SCI FIFO:

Can both TX and RX FIFO be used without enabling an interrupt? The system seems to request less interrupts for better motor control. Right now they are only enabling SCI RX and not SCI TX. Can TX still be used with RX FIFO?

CW->Yes, you can use RX FIFO and TX FIFO without the interrupts. I don't see any issues with enabling the interrupt for RX and not TX or vice-versa, however I have never tried this.

2. What is the process of reading from and writing to FIFO? The customer says they seem to be user invisible

CW-> To write the TX FIFO simply write to SCITXBUF, to read from the RX FIFO simply read from SCIRXBUF. Additionally, there are some status flags to indicate the state of the FIFO to the user. 

3. When using the Auto baud setting do both the RX and TX interrupts need to be enabled?

CW-> I don't think it is required, however the user will still need to clear the CDC bit in software after the ABD is set while CDC is 1, which indicates autobaud alignment has occurred. A that time the SCI transmit FIFO interrupt (TXINT) will be set, I assume the user could watch for the flag to occur in application code and clear the CDC bit. Again, I have never tried this but I don't foresee any issues.

Regards,
Cody

Cody,

I appreciate the quick response. This helped the customers understanding in these areas. They did however have a follow up question:

1) The TX interrupt was not set, only RX, yet after autobaud alignment hardware generates a TXINT interrupt. They are wanting to confirm that the software will clear the ABD bit and CDC bit in the interrupt service routine.

Thanks for the help,

Garrett

Garrett,

1) Did the value in the baud rate registers get updated after attempting the autobaud alignment? Was the customer able to see the ABD bit get set?

The software should have no problem clearing the ABD or CDC bit inside of an ISR, just simply clear the bits.

Regards,
Cody