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Add nrf52 power management for RAK3401 #1984

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42 changes: 30 additions & 12 deletions variants/rak3401/RAK3401Board.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,31 @@

#include "RAK3401Board.h"

#ifdef NRF52_POWER_MANAGEMENT
// Static configuration for power management
// Values set in variant.h defines
const PowerMgtConfig power_config = {
.lpcomp_ain_channel = PWRMGT_LPCOMP_AIN,
.lpcomp_refsel = PWRMGT_LPCOMP_REFSEL,
.voltage_bootlock = PWRMGT_VOLTAGE_BOOTLOCK
};

void RAK3401Board::initiateShutdown(uint8_t reason) {
// Disable SKY66122 FEM (CSD+CPS LOW = shutdown, <1 uA)
digitalWrite(SX126X_POWER_EN, LOW);

// Disable 3V3 switched peripherals and 5V boost
digitalWrite(PIN_3V3_EN, LOW);

if (reason == SHUTDOWN_REASON_LOW_VOLTAGE ||
reason == SHUTDOWN_REASON_BOOT_PROTECT) {
configureVoltageWake(power_config.lpcomp_ain_channel, power_config.lpcomp_refsel);
}

enterSystemOff(reason);
}
#endif

void RAK3401Board::begin() {
NRF52BoardDCDC::begin();
pinMode(PIN_VBAT_READ, INPUT);
Expand Down Expand Up @@ -31,18 +56,11 @@ void RAK3401Board::begin() {
// HIGH = FEM active (LNA for RX, PA path available for TX).
// TX/RX switching (CTX) is handled by SX1262 DIO2 via SetDIO2AsRfSwitchCtrl.
pinMode(SX126X_POWER_EN, OUTPUT);
#ifdef NRF52_POWER_MANAGEMENT
// Boot voltage protection check (may not return if voltage too low)
// We need to call this after we configure SX126X_POWER_EN as output but before we pull high
checkBootVoltage(&power_config);
#endif
digitalWrite(SX126X_POWER_EN, HIGH);
delay(1); // SKY66122 turn-on settling time (tON = 3us typ)
}

#ifdef NRF52_POWER_MANAGEMENT
void RAK3401Board::initiateShutdown(uint8_t reason) {
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@samschlegel samschlegel Mar 10, 2026

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had to move the block for power_config to be defined before begin and figured it made sense to just move it all

// Disable SKY66122 FEM (CSD+CPS LOW = shutdown, <1 uA)
digitalWrite(SX126X_POWER_EN, LOW);

// Disable 3V3 switched peripherals and 5V boost
digitalWrite(PIN_3V3_EN, LOW);

enterSystemOff(reason);
}
#endif
3 changes: 2 additions & 1 deletion variants/rak3401/platformio.ini
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Expand Up @@ -6,6 +6,7 @@ build_flags = ${nrf52_base.build_flags}
${sensor_base.build_flags}
-I variants/rak3401
-D RAK_3401
-D NRF52_POWER_MANAGEMENT
-D RADIO_CLASS=CustomSX1262
-D WRAPPER_CLASS=CustomSX1262Wrapper
-D LORA_TX_POWER=22
Expand Down Expand Up @@ -124,4 +125,4 @@ build_flags =
;-D MESH_DEBUG=1
build_src_filter = ${rak3401.build_src_filter}
+<helpers/ui/SSD1306Display.cpp>
+<../examples/simple_sensor>
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@samschlegel samschlegel Mar 10, 2026

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can remove if desired. I have a pretty minimal VSCode setup and I'm pretty sure this is just the default so maybe work keeping?

+<../examples/simple_sensor>
8 changes: 8 additions & 0 deletions variants/rak3401/variant.h
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Expand Up @@ -78,6 +78,14 @@ extern "C"
static const uint8_t A7 = PIN_A7;
#define ADC_RESOLUTION 14

// Power management boot protection threshold (millivolts)
// Set to 0 to disable boot protection
#define PWRMGT_VOLTAGE_BOOTLOCK 3300 // Won't boot below this voltage (mV)
// LPCOMP wake configuration (voltage recovery from SYSTEMOFF)
// AIN3 = P0.05 = PIN_A0 / PIN_VBAT_READ
#define PWRMGT_LPCOMP_AIN 3
#define PWRMGT_LPCOMP_REFSEL 4 // 5/8 VDD (~3.13-3.44V)

// Other pins
#define WB_I2C1_SDA (13) // SENSOR_SLOT IO_SLOT
#define WB_I2C1_SCL (14) // SENSOR_SLOT IO_SLOT
Expand Down