Have done a board with an AD9951. But I cannot get the DDS to respond my SPI commands. The output of the DAC stay flat or the SYNC_CLK stay at the crystal frequency/4.
Here is an exemple of how I write the CFR2 and a picture of the SCK and SDIO:
// Reference Clock
WriteSPI(0b00000001); // Write instruction of the register 0x01
WriteSPI(0b00000000); // Write data starting from MSB
WriteSPI(0b00000010); // Crystal OUT pin active
WriteSPI(0b00100000); // 4x Multiplication
LATCbits.LATC0=1; // I/O Update