Hello ADI support community,
I am using a demo board (DC1564A) with LTC2155-14. I need to change the control register of LTC2155-14 to enable the internal termination resistors (D1 bit of register 0x3). Somehow I can't read back the correct data using the read command.
Here is the steps I used:
1) Software reset (write 0x80 to register 0x0).
2) Clear reset (write 0x00 to register 0x0) (I understand this is optional. I tried with/without this step and got the same results).
3) Write 0x3 with data of 0x1F.
4) Read register 0x3 to confirm the register data. Here I can see the LTC2155-14 is trying to send out data, but the data are all zeros.
Attached is the waveform of the SPI interface for the above steps. The waveform seems to agree with the datasheet of LTC2155-14. But the SDO is low. The SPI clock cycle is slow (320ns). I didn't connect the ENC clock on the demo board. The SPI waveform (measured from FPGA integrated logic analyzer).
Many thanks in advance.
-Charlie
SPI Write/read diagram from LTC2155 datasheet
My test results:
Step 1) Software reset (write 0x80 to register 0x0)
Step 2) Clear reset (write 0x00 to register 0x0)
Step 3) Write 0x3 with data of 0x1F.
Step 4) Read register 0x3 to confirm the register data. Here I can see the LTC2155-14 is trying to send out data, but the data are all zeros.
