Unable to read Register from ADE7758

[LeanSol345]

Hi, I'm using Rasp-Pico to read registers from ADE7758. I want to read registers that are Non-Zero by default e.g. OPMODE (address:0x13; def-value:4) and I don't think external circuit for Voltage or Current measurements will matter while reading just these registers (default non-zero). SPI communication is initialized by phase=1; polarity=0 and the OUTPUT is 0 (ZERO).

I think there could be an issue while settling SPI, polarity or phase (but I'm unable to understand it). I've tried different polarity and phase bits in SPI but no use.
Here is the CODE, I'm writing:

read_command is to take the register in 8-bit as 0x7F will make communications register = 0111 1111, so the MSB will define read operation (Low logic) as per ADE7758 datasheet.

https://www.analog.com/en/products/ade7758.html

ChipSelect is initially zero to write register address to ADE7758 in order to read it. (As per my understanding, this is how it should be done.)

[ OPMODE = 0x13
spi = SPI(0, baudrate=5000000, phase=1, polarity=0, sck=Pin(2), mosi=Pin(3), miso=Pin(4))
cs = Pin(5, Pin.OUT)

def read_register(address):
try:
read_command = 0x7F & address
cs.value(0)
spi.write(bytearray([read_command]))
time.sleep_ms(1)
data = spi.read(1)
cs.value(1)
return data[0]

except Exception as e:
print("Failed to read from SPI: ", e)
return None

def main():
MODE_VAL = read_register(OPMODE)
print("Register Value is: ", MODE_VAL)

while True:
main()
time.sleep(2)
]

 

[aliarifat794]

The CS pin must be set low before sending any command and set high after the command is completed to properly frame the SPI communication. If you have an oscilloscope, please check if it is happening.

 

[LeanSol345]

The CS pin must be set low before sending any command and set high after the command is completed to properly frame the SPI communication. If you have an oscilloscope, please check if it is happening.

I think it's low before writing register bytes to slave IC.

 

[KlausST]

I think it's low before writing register bytes to slave IC.

"I think" is no good design practice.
you should KNOW.

This means in first place: reading the datasheet. It specifies "how long" before starting the clock the /CS pin needs to be LOW. (and how long it needs to be LOW after commuincation is finished).

And in second place: if you don´t know how it is: measure it.

It´s quite straight forward to look at the timing and levels of a (serial) communication when you encounter any problems.

5MHz for an SPI clock is rather fast. For sure there are faster SPI communcations. But why did you chose it to be that fast? Why not more relaxed?

Klaus