TMS320F28069F: what is SPI setting for half duplex communication.

Hae Ryong Jung

Expert 2150 points

Part Number: TMS320F28069F

Dear TI Members,

I am developing SPI communication between F28069 and other MCU.

MCU is SPI master, F28069 is SPI slave and using Rx, Tx ISR.

As I tested, both RxISR and TxISR were executed during any SPI communication.(seems to be full duplex)

It is quite confusing to handle, so I'd like to make it one way communication(half duplex)

For example, first, MCU send request to F28069, and MCU receive response from F28069 later

There is no sending/receiving data at the same time.

It makes me sure that F28069 is receiving request via RxISR during MCU sending,

To do this, what is initial SPI setting ?

Thanks in advance.

over 6 years ago

0 Marlyn Rosales Castaneda20 over 6 years ago

TI__Mastermind 22835 points

Hi Hae,
There is no specific setting to make the slave device be 'half duplex' instead of 'full duplex'.
However, you can clear or set the TALK bit according to when you want the device to transmit.
If you just want the device to listen you can set the TALK bit to 0. Then later on when you are ready for it to transmit set the TALK bit to 1.

Best Regards,
Marlyn

0 Hae Ryong Jung over 6 years ago in reply to Marlyn Rosales Castaneda20

Expert 2150 points

Hi Marlyn,

Thanks for your response.
As I have tried with TALK bit, still Rx, Tx ISR called at the same time.
Anyway, Thank for your comment, I will look into TALK bit more.

Best Regards,
Hae Ryong

0 Marlyn Rosales Castaneda20 over 6 years ago in reply to Hae Ryong Jung

TI__Mastermind 22835 points

Hae,

That is odd, the TALK bit should take care of that.

If after you look at it a bit more you still have questions/concerns please do not hesitate to ask.

Best Regards,

Marlyn

0 Marlyn Rosales Castaneda20 over 6 years ago in reply to Marlyn Rosales Castaneda20

TI__Mastermind 22835 points

Hae,
Have you been able to resolve your problem?

Best,
Marlyn

0 Hae Ryong Jung over 6 years ago in reply to Marlyn Rosales Castaneda20

Expert 2150 points

Instead of using TALK bit, I have called SPI_resetTxFifo() and SPI_enableTxFifo() at the end of Receiving packets and clearing all Rx buffer as well in RxISR.

clearing Tx buffer at the end of sending packet in TxISR.

then Rx, Tx seems to be OK.

I have set SPI clock to be 125kHz, then no error is detected for the communication.

Thanks for your help!

0 Marlyn Rosales Castaneda20 over 6 years ago in reply to Hae Ryong Jung

TI__Mastermind 22835 points

Hae,
I am glad you were able to resolve your issue. Thank you for posting your solution!
If you need anything else please don't hesitate to ask.

Best Regards,
Marlyn

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TMS320F28069F: what is SPI setting for half duplex communication.