What is a meaning of "PLL programming resolution" ?

[morimasaki51]

I use nRF52832-CIAA . I am troubled that RADIO frequency is as high as 200 kHz. BTW, What does "PLL programming resolution" mean in a datasheet?

[Jørn]

Hello morimasaki51

The shift in center frequency is within the typical value of 250kHz shown in the nRF52832 product specification for 1Msps BLE here.

The PLL programming resolution of 2kHz is an internal specification for the Phase Locked Loop, that generates the 2.4GHz signal. This value does not have any value for someone using our chip in development of a product, and should probably have been omitted from the datasheet. The value of interest for you would be the PLL channel spacing, of 1 MHz (this is actually called PLL programming resolution in the nRF51 series product specification). This is the smallest jump in frequency the radio can do when changing between channels.

Best regards

Jørn Frøysa

[morimasaki51]

Hello Jorn-san, Thank you for your reply. Can we adjust "PLL channel spacing" in your hint? morimasaki51

[Jørn]

The PLL channel spacing itself cannot be changed, it is the smallest change in frequency the radio is capable of making. If you look at the nRF52832 product specification, page 219 section 23.14.9 you have the radio frequency peripheral hardware register. It allows a change in frequency in 1MHz steps. Do note however this peripheral is blocked when using a SoftDevice as it will take control of it, see table 1 here.

[morimasaki51]

Hello Jorn-san I found that Radio frequency of nRF52832 is shifted by used SDK 11.0.0. morimasaki51

[morimasaki51]

External 32768Hz OSC solves this phenomenon.