What is a meaning of "PLL programming resolution" ?

RE: What is a meaning of "PLL programming resolution" ?

morimasaki51 — Sun, 20 Aug 2017 23:30:27 GMT

I misunderstood that the center frequency is adjusted with an external 32768Hz oscillator. In order to have the correct center frequency, it seems to be only updating the SDK from 11 to 12 or 13. morimasaki51

RE: What is a meaning of "PLL programming resolution" ?

Jørn — Fri, 11 Aug 2017 12:45:23 GMT

When you say external 32768Hz OSC, do you mean you're using an external oscillator, or a 32 kHz crystal? I am curious as to why this would affect your center frequency.

RE: What is a meaning of "PLL programming resolution" ?

morimasaki51 — Mon, 31 Jul 2017 07:00:58 GMT

External 32768Hz OSC solves this phenomenon.

RE: What is a meaning of "PLL programming resolution" ?

morimasaki51 — Mon, 31 Jul 2017 06:55:35 GMT

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

RE: What is a meaning of "PLL programming resolution" ?

Jørn — Tue, 04 Jul 2017 07:12:06 GMT

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.

RE: What is a meaning of "PLL programming resolution" ?

morimasaki51 — Tue, 04 Jul 2017 03:04:28 GMT

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

RE: What is a meaning of "PLL programming resolution" ?

Jørn — Mon, 03 Jul 2017 07:32:57 GMT

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