Hi Mustahsin, I have a couple of suggestions to try: I would recommend using 8-bit SPI frame (instead of 16-bit frames as you are currently using). The reset command is only 8-bits and not all other commands will be a multiple of 16 bits, so it may be easier to simply send SPI command byte by byte. The 2 MHz SCLK is a little fast for the ADS1256 if you're using the nominal 7.68 MHz ADC clock. The SPI clock should not exceed 1/4th the frequency of the ADC clock, so you might try using a a slightly lower SCLK frequency. The continuous SCLK is probably causing some issues with reading registers. The ADS1256 has a t6 delay required between the command bytes and the register data byte(s). See figure 34 in the ADS1256 datasheet. If you can try to capture a single RREG command on the oscilloscope with the /CS signal included so that you can see how this command is framed. For troubleshooting, it is okay to loop 1000 times, but I would recommend including the toggling of /CS in the loop to make it easier to differentiate between commands.
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