Hello to everyone,
I have strange outputs when communicating with AD7381-4 and am hoping that someone can give me some tips.
First I would provide some basic information:
The data frame contains 16 bits. The MSB determines a read or write operation, followed by 3 bits of the register address. The rest 12 bits are the data to be written when the operation is a write. Details are in the following picture:
There are 5 registers available, the addresses are from 0x1 to 0x5. Details are in the following picture:
To read the registers, send a read command first, then send another command to get the register content.
Now here is my problem:
I use NRF52840 DK board to communicate with it:
The function spi sends its input to the ADC and display the received data:
When I send read commands, there is no useful data, but when I send write commands, I receive fix data:
Read register 0x1 -> receive random numbers.
Read registers other than 0x1 -> receive 0x0.
Write anything to register 0x1 -> receive 0x800 (preset content of register 0x4).
Write anything to register 0x2 -> receive 0x7ff (preset content of register 0x5).
Write anything to register 0x4 or 0x5 -> receive 0x220.
I think the timing specification of my NRF MCU is correct, since I can somehow get fix outputs. However, I still can't control the ADC.
So can anyone please share some tips?