We are using the TMS5704357 Processor and are trying to communicate with the MMC5983 device, we also tried the MCU9250 and had a similar problem where the communication does not work. the similarity of the parts are the 2 devices are they are both magnetometers they have SPI I2c dual use pins, and we have a different processor that works for both of them but there is something different our TMS5704357 that is not allowing communication.
We think it is the transactions
Here is the logic analyzer of the working processor
The first transaction always seems to be different then the rest
Subsequent transactions follow what we expect
and the TMS5704357 all the transactions are like this, where there is no reply
Changing how MOSI starts out on the TMS570 to try to make it match closer to the one that works
We have been changing the setting quite a bit to try and match the working transaction for the different processor but we cannot seem to quite duplicate it, the differences that we see are:
- The low signal a half clock cycle early
- The chip select go low closer to the transaction
- The one clock pulse period that is longer after 8 bits
any suggestions?
