Content originally posted in LPCWare by IanB on Sat May 21 00:34:13 MST 2016
Having to change the MCU seems a bit melodramatic to me!
I agree with Ex-Zero here - especially as the AD7792 is further complicated by having the DOUT/RDY pin as part of the interface - A lot easier to implement the SSEL in software as a GPIO pin.
As some of the data are 2 bytes long, it is easier to set the SSP interface to 16 bits for that data, so that it can be read in one operation.
The SSEL function isn't too clever in the LPC15xx either - it all goes horribly wrong if there is an interrupt between two SSP reads, so, again, it is far easier to implement the SSELs as GPIO.