NRF24L01 Continuous Carrier

RE: NRF24L01 Continuous Carrier

ketiljo — Thu, 02 Sep 2021 12:43:23 GMT

Hi Tony

Is this the crystal you're using? https://www.digikey.com/en/products/detail/abracon-llc/ABM11-16.000MHZ-B1U-T/9997511

If so, the CL value is 10 pF. The load caps are calculated as follows:

Ccap = CL *2 - Cpin, where C pin = ~2 pF

For a 10 pF crystal, the caps should then be 18 pF.

When you touch the crystal with a probe, the capacitance in the probe will pull the frequency. The best way to check the frequency of the crystal is to use a spectrum analyzer and measure the exact frequency of a unmodulated carrier.

cheers,

Ketil

RE: NRF24L01 Continuous Carrier

ToBeDD — Wed, 01 Sep 2021 13:17:17 GMT

Hi Ketil,

thank you for qour quick reply.

Meanwhile I've implemented the "Appendix C" Procedure from Datasheet REV2.0 which worked first try. This also proves that the SPI and my Codebase is in working condition.

For the schematic: I've used the reference design from datasheet REV2.0 "Appendix D". My Crstal is a 16MHz Type (ABM11-16.000MHZ-B1U-T from Abracon). It runs with a nice sinusodial at perfekt frequency (verified with scope).

Is there something else that could go wrong here?

Thank you in advance!

Tony

RE: NRF24L01 Continuous Carrier

ketiljo — Wed, 01 Sep 2021 12:03:49 GMT

Hi Tony

The procedure for setting up a carrier is the same for the + and non + devices. The only difference between the two is that the + version can do data in ACK packets plus a few more minor thing.

If the procedure doesn't work, there's something going on with your design. Can you post the schematic for the nRF24L01 part and the 16 MHz crystal spec please?

Ketil