In this application, only four(4) wires of SPI signal(SCLK, CS, SI, SO) are connected. Clock is set to 2MHz, when I tried to read data (for an example, PARTNUMBER) from CC1120, I sent 0xaf8f through SPI to CC1120, and I didn't get the expected chip ID returning from SO pin. Please note the signals on SCLK, CS, and SI pins seem satisfying the requirement, but the signal on SO pin is always high(0xff) when SI is asserted. Unfortunately, I can't attach the oscilloscope screenshots here. Could you please provide any information/suggestion to tackle this issue? Is there any successful instance of this application we can share?
A combined screenshot is attached for reference. Please note the black CS signal is manually added for clarification.
Thanks in advanced for help!
Yang Liu
