Other Parts Discussed in Thread: ADS8678
The SPI signals for an ADS8674/ADS8678 device are connected to GPIO lines on a processor and controlled through software to implement the SPI protocol for the device. After power on, the first command to the device is to read the AUTO_SEQ_EN register (0x01), which should return a value of 0x0F (ADS8674) or 0xFF (ADS8678). However, the value received is 0x0E or 0xFE, depending on the device. Multiple devices have been used with the same results.
The timing for the operation is shown in the scope trace, and it seems to match the requirements in the data sheet. Please note the clock frequency is quite slow in order to maintain the duty cycle specification for the device, but there is no minimum specification for the clock frequency.
Also, reading and writing other registers does not seem to operate correctly. Are there any actual timing traces available from the evaluation module that can be used as reference to try to find the problem?
Thanks