Hello,
I am utilizing a Laird (now ezurio) bl5340 module on my custom board which requires the internal 13.5pF caps to be set for the high frequency 32Mhz clock source as specified by their datasheet:
I have done this by adding the following to my custom board deconfig file as shown here:
Within my custom board I'm also using an external 32kHz clock for the low frequency control with 5ppm accuracy in the hope of getting better BLE performance. I would like confirmation that the above config file will correctly utilize the external clock source. Here are the schematics for how we hooked up the clock:
Used this information from the Laird data sheet to determine this configuration for the wiring:
My question is regarding my defconfig file and if those options are correct. When I look at the bl5340_dvk defconfig file for example, they have the same settings for the HFXO clock, so I think that is right, but that dev kit also uses an external low frequency oscillator, but I don't see an explicit config for setting the low frequency controller to use the external source. Am I misunderstanding what the "CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=y" option does? Is this not required, and does the system automatically know to utilize the external source? Do I need to set "CONFIG_CLOCK_CONTROL_NRF_K32SRC_20PPM=y" as that is the lowest option, my source is rated at 5ppm? I'm using MPSL (switches between ble and custom layer for synch purposes) so I believe these timings actually do impact how the radio resources get split up and I would like to be as efficient as possible and utilize this very nice clock source to its fullest. I'm assuming I don't need to set any of the internal LFXO caps due to our rail to rail clock setup? Help is greatly appreciated.
