Hi Grisha,
For register 0x500, load the harmonic value. In your case it would be value 2. The since you need to enable the spur reduction function for spur A, you need set bit 7. All together, you have to write 0x82 in register 0x0500. In register 0x0503, the full 360 degree phase shift is represented by a full scale code. This means that a 180 degree phase shift is equivalent to setting the MSB of the register.
The full scale amplitude of the cancellation spur is approximately -60dBc when the Gain bit (0x0500 bit 6) is logic 0, and -54dBc when it is logic 1. Since we wrote 0x82, the full scale amplitude is already set to -60dBc.
Best Regards
Louijie