RAK4270 TCXO Settings

Issue: TCXO

Setup: Custom Firmware



I am using custom firmware I created in STM32CubeIDE. It’s been working great, except with lower data rates. I enabled Low Data-rate Optimization and it’s now semi-reliably working down to SF11-BW10khz, or SF12-BW20khz, but cannot reliably do SF12-BW10khz or lower.

I suspect the issue is with the clock timing accuracy. The datasheet is unclear about the TCXO that’s used. Despite the 0ohm value for the decoupling capacitor on the schematic, I do believe there is a TCXO rather than a regular crystal oscillator, because the module does not work without enabling DIO3 as TCXO control. I have tried giving the TCXO over 150ms to settle, and I’ve tried running it from 1.8v to 3.3v.

I would like to minimize the settling delay time since I’m rx duty cycling to reduce power when using higher data-rates. I would also like to provide the TCXO with the correct voltage level. Does anybody know what TCXO is used so that I can lookup it’s characteristics, determine if it’s capable of better accuracy, determine the minimum settling delay, and determine the correct voltage settings?

Hi @mintenj ,

Here’s the specs of the TCXO.

11300001217D(X1G004131004200)datasheet.pdf (1.0 MB)

I hope this can help you optimized your FW.

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