TMS320F280049: SPIA and SPIB difference

Hi expert,

My customer is using F280049 for OBC DCDC project, F280049 serve as PFC control.

The F280049 SPIB is set as slave, communicating with F28377S.

they found that after adding the main power , F280049 spi can not run into interrupt.

they use the ISO7741 to do the isolation and add the filter so the waveform from SPI pin is very clean.

they also make the spi baudrate drop from 1MHz to 200kHz.

then they change it to spiA, the issue solved. 

so I want to double check what is difference between SPIA and SPIB.

pin configuration is as below, any other thing is not change. and SPIB works well without high power.

280049 slave development(old)

SPIB GPI014/c1k/(also use GPIO28)
SPIB GPI029/ste/
SPIB GPI030/simo/
SPIB GPI031/somi/

280049 slave development
SPIA GPI056/c1k/
SPIA GPI057/ste/
SPIA GPI016/simo/
SPIA GPIO17/somi/

the package they use is 100PIN.

BR

Emma