I'm using the AD5142 for my application. I can write to the device and update the wiper position etc fine using the description of the SPI interface and protocol in the data sheet. However, I cannot currently use the read functionality (Command number 3). Unlike using the SDO pin for daisy chaining devices, the datasheet only briefly mentions that SDO can also be used to read internal device state via command number 3 and never gives and example or description of how.
- For instance, do I need to use a 24 clock cycle and read the result back in the last 8 bits after the 16-bit request?
- The datasheet says that the the SDO pin will provide 16-bit shifted version of SDI input for daisy chaining. This seems to conflict with the statement that it can be used for reading via command 3 as well.
Another ambiguity in the datasheet are Tables 11 and 17 which describe the meaning of the address bits in the SPI command. There is a column called "Stored Channel Memory" that I cannot find a description for in the datasheet. Is this the addressing used for selecting the address within EEPROM to read back? And just so its clear: I have a 2.2k pullup on SDO as required in the datasheet.
Added that I have 2.2k pullup on SDO
[edited by: jonnew at 2:20 PM (GMT 0) on 15 Jul 2020]