TMS320F280039C: Tamagawa T-Format Reference Design, if not connect with the encoder, the SPI send wrong data, how to solve this?

NAN LI

Hi, Every experts,

I have some problems, when I use the Tamagawa T-format absolute-encoder reference design, when the MCU connected to the encoder, the wave of Rx and Tx are right.

but when I disconnected the encoder , I found the the TX wave is very abnormal, as the first picture shows: the yellow line is the TXEN signal，the blue line is SPI SOMI（TX），

Obviously, in some cyles, the TXEN signal is pull down before the TX sending is complete. and in some cyles After Tx send the signal the Tx Pin is not pull up.

This is difference with using SCI peripheral.

the sencod picture is a normal wave when connected to a encoder.

over 3 years ago

0 NAN LI over 3 years ago

Prodigy 80 points

Supplementary instruction: the abnormal cyles looks like there's no stop bit, One period has, One period that doesn't .

0 NAN LI over 3 years ago

Prodigy 80 points

I use the CLB simulation to check this phenomenon, it show the same error result,

The yellow line is the OUTLUT_5 signal (use the F28388D core), that is write to TXEN, Hope you can solve this Bug

the blue line is BOUNDARY in0

0 NAN LI over 3 years ago

Prodigy 80 points

In the reference manual, there are four state: IDLE->TRANSMIT_DATA->WAIT_FOR_START->RECEIVE_DATA->IDLE，I think the reason of the problem is that if do not connect the encoder, The WAIT_FOR_START state will switch to IDLE state, and START_OPERATION directly. and it cause the problem. hope you can solve this.