Hi Siyavash,
Can I ask for scope shots of your digital interface lines?
Upon power-up a reset should be initiated so as to place the digital interface to a known state. This is done by writing 40 consecutive 1’s to the part. After the reset, the part can be configured for the application.
I noticed that you wrote 48 consecutive 1’s, If this is to reset the part, the extra byte is not necessary.
It is okay for the SYNC pin to be floating as it has an internal pull-up resistor connected to DVDD.
In your code, you wrote:
input(PIN_a5) output_high(pin_a3); output_low(pin_b4);
What are these for?
In general, the DOUT/RDY line is tri-stated when CS is high. So, for debug, I suggest that you tie CS low. After performing the reset, you should see DOUT/RDY pulsing at the default output data rate (50 Hz). I suggest you now try to write to a register, for example, the mode register to change the output data rate. If the write operation works correctly, you will see DOUT/RDY pulse at the new output data rate. Now, try to read back the mode register to confirm that the data read back is the same as the data that you loaded to the register. The above sequence will confirm whether your read and write routines are correct.
In general, I recommend that DIN and SCLK are held high when read and write operations are not being performed. This makes the serial interface more robust. Also, the correct number of SCLK pulses need to be applied for every read and write operation. An incorrect number of SCLJK pulses will cause the serial interface to lose synchronization.
Thanks and Best Regards,
Chris