I try to establish a communication with the TM4C123GXL and the AD9826. For the communication I use the SPI interface of the TM4C123GXL. The SSI Rx and Tx are connected via a 3 kOhm resistor.
The AD9826 requires the following timings.
With the SPI peripheral from TM4C123GXL I generated the following timings, where blue = clock, turquoise = data and purple = sload
Unfortunately I do not get a response from the AD9826 or rather it is wrong. I try to read the content of the configuration register which has the address 0x000. So by adding the address bit it would be 0x1000000. The response which I expect would be 11111000 - which is the default value for the configuration register.
So this raises the following questions to me.
- Does the AD9826 need a continuous clock? (This would be a problem, as the TM4C123GXL SPI peripheral cannot provide it).
- Is this three wire "SPI" a SPI kind of communication? (For me it looks like the MICROWIRE frame format)
- Any idea what I am doing wrong?
- Is the read bit high or low? I assumed that it is high from the picture below. There is no further indication in the datasheet.