The AD9540 software was create with visual basic, so I don't have any Matlab code to forward. That said, there's a few threads on DDS engineering zone that might help. See the link below for one. The SPI interface to the AD9540 is like most all other DDSs,
https://ez.analog.com/message/171288#171288
Here's some quick steps to program the AD9540 to see if you're communicating with the device.
Basically it turns off and on the SYNC_CLK.
1) Power up the part
2) Apply the REF CLK source
3) Send a master reset.(This places the internal registers in a known state)
4) Monitor the SYNC_CLK pin 18, it should be toggling.
5) Write to register 0x00h bit 4 (Disable SYNC_CLK) Consists of one byte for the instruction byte and 4 bytes of data so 40 SCLKs/SDIOs right?
6) Send an IO_UPDATE pulse. Note, the pulse must be wider that the SYNC_CLK period.
7) The SYNC_CLK should turn off. If so, you're communicating.
Hope this helps.
