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feat: Integrate BME680 Bosch BSEC support for RAK4631 #2634

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59cee5c
feat: Integrate BME680 Bosch BSEC support for RAK4631
NickDunklee May 27, 2026
e501704
Am idiot, and deleted some of the adafruit code path
NickDunklee May 27, 2026
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108 changes: 103 additions & 5 deletions src/helpers/sensors/EnvironmentSensorManager.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,28 @@
// Sensor library includes and static driver instances
// ============================================================

#if ENV_INCLUDE_BME680_BSEC
#ifndef TELEM_BME680_ADDRESS
#define TELEM_BME680_ADDRESS 0x76
#endif
#define TELEM_BME680_SEALEVELPRESSURE_HPA (1013.25)
#include <bsec.h>
#include <Adafruit_LittleFS.h>
#include <InternalFileSystem.h>
static const uint8_t bsec_config_iaq[] = {
#include "config/generic_33v_3s_28d/bsec_iaq.txt"
};
static Bsec bsec_iaq;
static float bsec_temperature = 0;
static float bsec_humidity = 0;
static float bsec_pressure_hpa = 0;
static float bsec_iaq_val = 0;
static uint8_t bsec_accuracy = 0;
static bool bsec_active = false;
static bool bsec_data_ready = false;
#define BSEC_STATE_FILE "/bsec_state.bin"
#endif

#ifdef ENV_INCLUDE_BME680
#ifndef TELEM_BME680_ADDRESS
#define TELEM_BME680_ADDRESS 0x76
Expand Down Expand Up @@ -217,9 +239,10 @@ static void query_bme680(uint8_t ch, uint8_t, CayenneLPP& lpp) {
if (BME680.performReading()) {
lpp.addTemperature(ch, BME680.temperature);
lpp.addRelativeHumidity(ch, BME680.humidity);
lpp.addBarometricPressure(ch, BME680.pressure / 100);
lpp.addAltitude(ch, 44330.0 * (1.0 - pow((BME680.pressure / 100) / TELEM_BME680_SEALEVELPRESSURE_HPA, 0.1903)));
lpp.addAnalogInput(ch, BME680.gas_resistance);
const float pressure_hpa = BME680.pressure / 100.0f;
lpp.addBarometricPressure(ch, pressure_hpa);
lpp.addAltitude(ch, 44330.0f * (1.0f - powf(pressure_hpa / (float)TELEM_BME680_SEALEVELPRESSURE_HPA, 0.1903f)));
lpp.addGenericSensor(ch, BME680.gas_resistance);
}
}
#endif
Expand Down Expand Up @@ -431,6 +454,63 @@ static void query_rak12035(uint8_t ch, uint8_t sub_ch, CayenneLPP& lpp) {
}
#endif

#if ENV_INCLUDE_BME680_BSEC
static void bsec_load_state() {
using namespace Adafruit_LittleFS_Namespace;
File f = InternalFS.open(BSEC_STATE_FILE, FILE_O_READ);
if (!f) return;
uint8_t state[BSEC_MAX_STATE_BLOB_SIZE];
f.read(state, BSEC_MAX_STATE_BLOB_SIZE);
f.close();
bsec_iaq.setState(state);
}

static void bsec_save_state() {
using namespace Adafruit_LittleFS_Namespace;
uint8_t state[BSEC_MAX_STATE_BLOB_SIZE];
bsec_iaq.getState(state);
InternalFS.remove(BSEC_STATE_FILE);
File f = InternalFS.open(BSEC_STATE_FILE, FILE_O_WRITE);
if (!f) return;
f.write(state, BSEC_MAX_STATE_BLOB_SIZE);
f.close();
}

static uint8_t init_bme680_bsec(TwoWire* wire, uint8_t addr) {
bsec_iaq.begin(addr, *wire);
if (bsec_iaq.bsecStatus != BSEC_OK) return 0;

bsec_iaq.setConfig(bsec_config_iaq);
if (bsec_iaq.bsecStatus != BSEC_OK) return 0;

bsec_virtual_sensor_t outputs[] = {
BSEC_OUTPUT_IAQ,
BSEC_OUTPUT_SENSOR_HEAT_COMPENSATED_TEMPERATURE,
BSEC_OUTPUT_SENSOR_HEAT_COMPENSATED_HUMIDITY,
BSEC_OUTPUT_RAW_PRESSURE,
BSEC_OUTPUT_STABILIZATION_STATUS,
BSEC_OUTPUT_RUN_IN_STATUS,
};
bsec_iaq.updateSubscription(outputs, 6, BSEC_SAMPLE_RATE_LP);
if (bsec_iaq.bsecStatus != BSEC_OK) return 0;

bsec_load_state();
bsec_active = true;
return 1;
}

static void query_bme680_bsec(uint8_t ch, uint8_t, CayenneLPP& lpp) {
if (!bsec_data_ready) return;
bsec_data_ready = false;
lpp.addTemperature(ch, bsec_temperature);
lpp.addRelativeHumidity(ch, bsec_humidity);
lpp.addBarometricPressure(ch, bsec_pressure_hpa);
lpp.addAltitude(ch, 44330.0f * (1.0f - powf(bsec_pressure_hpa / (float)TELEM_BME680_SEALEVELPRESSURE_HPA, 0.1903f)));
lpp.addGenericSensor(ch, (uint16_t)bsec_iaq_val);
lpp.addAnalogInput(ch, (float)bsec_accuracy);
}
#endif

// ============================================================
// Sensor descriptor table
//
Expand Down Expand Up @@ -458,6 +538,9 @@ static const SensorDef SENSOR_TABLE[] = {
#ifdef ENV_INCLUDE_BME680
{ TELEM_BME680_ADDRESS, "BME680", init_bme680, query_bme680 },
#endif
#if ENV_INCLUDE_BME680_BSEC
{ TELEM_BME680_ADDRESS, "BME680+BSEC", init_bme680_bsec, query_bme680_bsec },
#endif
#if ENV_INCLUDE_BME280
{ TELEM_BME280_ADDRESS, "BME280", init_bme280, query_bme280 },
#endif
Expand Down Expand Up @@ -780,11 +863,13 @@ void EnvironmentSensorManager::stop_gps() {
MESH_DEBUG_PRINTLN("Stop GPS is N/A on this board. Actual GPS state unchanged");
#endif
}
#endif // ENV_INCLUDE_GPS

#if ENV_INCLUDE_GPS || defined(ENV_INCLUDE_BME680_BSEC)
void EnvironmentSensorManager::loop() {
static long next_gps_update = 0;

#if ENV_INCLUDE_GPS
static long next_gps_update = 0;
if (gps_active) {
_location->loop();
}
Expand Down Expand Up @@ -812,5 +897,18 @@ void EnvironmentSensorManager::loop() {
next_gps_update = millis() + (gps_update_interval_sec * 1000);
}
#endif
#if ENV_INCLUDE_BME680_BSEC
if (bsec_active && bsec_iaq.run()) {
uint8_t prev_accuracy = bsec_accuracy;
bsec_temperature = bsec_iaq.temperature;
bsec_humidity = bsec_iaq.humidity;
bsec_pressure_hpa = bsec_iaq.pressure / 100.0f;
bsec_iaq_val = bsec_iaq.iaq;
bsec_accuracy = bsec_iaq.iaqAccuracy;
bsec_data_ready = true;
if (bsec_accuracy >= 2 && bsec_accuracy > prev_accuracy)
bsec_save_state();
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@cwichura cwichura May 28, 2026 •
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There doesn't appear to be any backoff here. If accuracy is updating every loop(), you will be doing a lot of filesystem writes. And there are concerns in other threads about RAKs corrupting their filesystem during writes under various trigger conditions. Maybe update this to include a millis() check as well, so that it isn't constantly overwriting the state file in rapid succession? How important is it that it update the state persistence? Could it limit it to every minute? five minutes? Or does the BSEC library itself already gate accuracy checks and so you have an inherent backoff from the library?

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@NickDunklee NickDunklee May 28, 2026

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Oooh, that's a good observation, I like it. Once the sensor gets into a calibrated state (except for on companions) it just remains there for hours on end. If the sensor gets into a calibration flux like on companions, it would otherwise be writing very frequently as you said. I will check into that.

}
#endif
}
#endif
#endif // ENV_INCLUDE_GPS || ENV_INCLUDE_BME680_BSEC
2 changes: 1 addition & 1 deletion src/helpers/sensors/EnvironmentSensorManager.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ class EnvironmentSensorManager : public SensorManager {
#endif
bool begin() override;
bool querySensors(uint8_t requester_permissions, CayenneLPP& telemetry) override;
#if ENV_INCLUDE_GPS
#if ENV_INCLUDE_GPS || defined(ENV_INCLUDE_BME680_BSEC)
void loop() override;
#endif
int getNumSettings() const override;
Expand Down
15 changes: 15 additions & 0 deletions variants/rak4631/fix_bsec_lib.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
Import('env')
import os

# Bosch has a goof in their PlatformIO packaging making linking fail.
# The BSEC library's extra_script.py selects cortex-m4/libalgobsec.a (soft-float ABI).
# nRF52840 compiles with -mfloat-abi=hard, requiring the fpv4-sp-d16-hard blob.
# Workaround to prepend the hard-float path so the linker finds it before the
# soft-float one.
bsec_hard = os.path.join(
env.subst('$PROJECT_DIR'),
'.pio', 'libdeps', env.subst('$PIOENV'),
'BSEC Software Library', 'src',
'cortex-m4', 'fpv4-sp-d16-hard'
)
env.Prepend(LIBPATH=[bsec_hard])
5 changes: 5 additions & 0 deletions variants/rak4631/platformio.ini
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@
extends = nrf52_base
board = rak4631
board_check = true
extra_scripts = ${nrf52_base.extra_scripts}
post:variants/rak4631/fix_bsec_lib.py
build_flags = ${nrf52_base.build_flags}
${sensor_base.build_flags}
-I variants/rak4631
Expand All @@ -21,6 +23,8 @@ build_flags = ${nrf52_base.build_flags}
-D SX126X_CURRENT_LIMIT=140
-D SX126X_RX_BOOSTED_GAIN=1
-D ENV_INCLUDE_RAK12035=1
-UENV_INCLUDE_BME680
-D ENV_INCLUDE_BME680_BSEC=1
build_src_filter = ${nrf52_base.build_src_filter}
+<../variants/rak4631>
+<helpers/sensors>
Expand All @@ -31,6 +35,7 @@ lib_deps =
${sensor_base.lib_deps}
adafruit/Adafruit SSD1306 @ ^2.5.13
sparkfun/SparkFun u-blox GNSS Arduino Library@^2.2.27
boschsensortec/BSEC Software Library @ ^1.8.1492

[env:RAK_4631_repeater]
extends = rak4631
Expand Down