TX PLL programming (VCO and VCOCAP Code Selection)


#1

Hi,

Trying to follow the VCO and VCOCAP Code Selection algorithm so I can program the TX PLL to my desired frequency.
I start out with a reference clock of 25 MHz and want to program my TX PLL to 2140 MHz.
Then calculate my Integer and Fractional, NINT= 0xAB, NFRAC= 0x199999.
I also set up the charge pump currents as described in the starter guide.
Then I start the VCO and VCOCAP Code Selection.
I sweep over the different VCOs and write the min and max VCOCAP values and check the output of the comparators after each write. The output of the comparators always stays the same for every VCO/VCOCAP, 0x43. (VTUNE_H=0, VTUNE_L=1).
According to the flow chart I should be panicking, but I was hoping there was something wrong with my setup :slightly_smiling:
According to the register description, the comparators should be on by default (ADR: 0x1B).
Here are my register settings:
ADR: 0x9, DATA: 0x41
ADR: 0x5, DATA: 0x3A
ADR: 0x34, DATA: 0x2
ADR: 0x41, DATA: 0x19
ADR: 0x45, DATA: 0x78
ADR: 0x44, DATA: 0xB
ADR: 0x10, DATA: 0xAA
ADR: 0x11, DATA: 0x99
ADR: 0x12, DATA: 0x99
ADR: 0x13, DATA: 0x99
ADR: 0x15, DATA: 0xB1
ADR: 0x16, DATA: 0x8C
ADR: 0x17, DATA: 0xE3,
ADR: 0x18, DATA: 0x40