Fix RAK3401 SKY66122-11 FEM control: enable CSD/CPS for proper PA/LNA operation#6
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…gative claims number.
…rect-Release-of-RefCountedDigitalPin Fixed RefCountedDigitalPin.h and SSD1306Display for Heltec v4
…reply `gps sync` reply: fill buffer with text
… LNA operation The RAK13302 1W module uses a Skyworks SKY66122-11 front-end module with three digital control pins (CSD, CTX, CPS) that must be actively driven by the host MCU. The previous code only managed CTX (GPIO 31) — toggling it for TX/RX — but never initialized CSD (GPIO 24) or CPS (GPIO 21), leaving them floating with no pull-up/pull-down resistors on the PCB. With floating CSD and CPS, the SKY66122 was in an undefined operating mode: - The 30 dB TX PA may not have been reliably engaging - The 16 dB RX LNA was never reliably active, degrading receive sensitivity
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Needs to be rebased at least after #9777 |
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preamble: I was talking to someone about their RAK3401 board on Discord and dived into datasheets and current implementation. I asked them to test and come back with findings, but I strongly believe the FEM isn't being controlled properly and this can cause RX sensitivity to be bad and perhaps even cause power/overheating issues.
The RAK13302 1W module uses a Skyworks SKY66122-11 front-end module with three digital control pins (CSD, CTX, CPS) that must be actively driven by the host MCU. The previous code only managed CTX (GPIO 31) — toggling it for TX/RX — but never initialized CSD (GPIO 24) or CPS (GPIO 21), leaving them floating with no pull-up/pull-down resistors on the PCB.
With floating CSD and CPS, the SKY66122 was in an undefined operating mode:
I have 4 variants for you to try:
I expect variant number 4 to have the best improvement. When replying with your findings please mention the builds you have tested!
Following the comment from Heltec engineer I also applied the register patch here. It should help with keeping AGC in check.
I don't have a RAK13302 device so I cannot test this myself.
References:
Mirror of meshcore-dev#1836