I'm trying to operate the Fast NCO switching feature of AD6688 / AD6902 on 5 different phases with no success.
I'll explain what I did so far :
Step 1 :
Calculate 5 FTWs and set each in the appropriate NCO channel :
1. Chose NCO channel to update by setting Bits[3:0] in the NCO control registers 0x0374.
2. Calculate the FTW using this formula : (page 49 in the Data Sheet) and setting the 48bits word into registers : 0x0376 to 0x037B.
3. Repeat steps 1 through 2 for all other 4 channels.
Step 2 :
Chose the GPIO option for transferring between channels - GPIO_B1 in Edge Control Mode :
1. Wrote 0x0 to Bits[7:4] in Register 0x0042.
2. Configured the NCO channel selector in GPIO edge control mode by setting Bits[7:4] in the NCO control registers 0x0374 to 0xB.
3. Configured the wrap point for the NCO channel selection by setting Bits[3:0] in the NCO control registers 0x0374 to 4.
Step 3 :
Toggling GPIO_B1 0>1
1. What am I doing wrong ?
2. Does setting the selector - red circled FTW/POW write index (in the below Figure 75.) is by writing to register 0x0374 bits [3:0] ?
Add second question
[edited by: KobiP at 11:09 AM (GMT -4) on 4 Sep 2023]