I have been trying unsuccessfully to configure and verify the configuration register on the ADS8330. From the data sheet and other documents it appears the SPI should be CPOL = 0, CPHA = 1. When I try and write 0x5FD to the configuration register, I read back 0x9FA. The waveforms are shown below. Been fighting this for a bit so any help would be greatly appreciated. (Note: I have also tried CPHA = 0 with no luck there either)
Hello Tim,
I think the output is correct, but you are not reading on the correct clock edge.
The ADS8330 launches the MSB on the falling edge of chip select, and then launches the remaining bits on the falling edge of SCLK. The ADS8330 also captures data on the falling edge of SCLK.
When writing to the ADC, the host should update data on the rising edge of SCLK. Also, when reading from the ADC, the host should capture data on the rising edge of SCLK as well.
Reading the SDO pin on the rising edge of SCLK results in a register value of 0x4FD, which matches what you wrote to the register (ignoring the value of D8)
I think you need to adjust your settings for the SPI port. SPI mode 00 should work.
Regards,
Keith Nicholas
Precision ADC Applications
