Hardware

Software

Build

Dependencies

make -C esp-open-sdk-for-micropython
# install 'esp-sdk' wrapper that forwards calls to docker, it mounts full $HOME
docker run --rm -u $UID -v $HOME/bin:/target esp-open-sdk install-wrapper
# usage
https://github.com/larsks/docker-image-esp-open-sdk#wrapper-script

Prepare

cd micropython
# get submodules for esp8266 port
esp-sdk make -C ports/esp8266 submodules
# build micropython cross compiler (<1min)
esp-sdk make -C mpy-cross
# patch micropython, cf https://github.com/devbis/st7789_mpy/#overflow-of-iram1_0_seg
git apply ../0001-fix-iram1-overflow-move-bsec-text-to-irom0.patch

Build

# build port (~30s)
cd micropython/ports/esp8266
#esp-sdk make clean
esp-sdk make USER_C_MODULES=../../../modules

Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
Including User C Module from ../../../modules/bsec
...
LINK build-GENERIC/firmware.elf
 text data bss dec hex filename
 661645 1016 67640 730301 b24bd build-GENERIC/firmware.elf
Create build-GENERIC/firmware-combined.bin
esptool.py v1.2
flash 34832
 .text 31444 at 0x40100000
 .data 1016 at 0x3ffe8000
 .rodata 2332 at 0x3ffe8400
padding 2032
irom0text 627872
total 664736
md5 72bb9964e63979e5d79471410fb143b1

Flash

Usage

import machine
import time
import bsec
i2c = machine.I2C(scl=machine.Pin(5), sda=machine.Pin(4), freq=100000)
bme680 = bsec.BME680_I2C(i2c)
bme680.init()
while True:
 measurement_timestamp_ns = time.time_ns()
 bme680.force_measurement(measurement_timestamp_ns)
 delay_us = bme680.get_read_data_delay_us()
 time.sleep_us(delay_us)
 data = bme680.read_data(measurement_timestamp_ns)
 print(data)
 next_call_timestamp_ns = bme680.get_next_call_timestamp_ns()
 delay_us = max(next_call_timestamp_ns - time.time_ns(), 0) // 1000
 print("sleep (in s)", delay_us/1000000)
 time.sleep_us(delay_us)
# example output:
# {'iaq': 144.758, 'staticIaqAccuracy': 3, 'gasResistance': 171795.0, 'rawHumidity': 49.9882, 'co2Accuracy': 3, 'breathVocAccuracy': 3, 'staticIaq': 103.249, 'iaqAccuracy': 3, 'breathVocEquivalent': 1.63182, 'co2Equivalent': 1032.49, 'humidity': 65.8691, 'pressure': 100328.0, 'temperature': 24.1201, 'rawTemperature': 28.7868}
# After iaqAccuracy reaches 3, i.e. calibrated:
# Save state
calibrated_state = bme680.get_state()
# Save to persistent memory
state_filename = 'bsec_bme680_calibrated_state.bin'
with open(state_filename, 'wb') as f:
 wrote = f.write(calibrated_state)
print('wrote', wrote, 'bytes on file', state_filename)
# Load from persistent memory
with open(state_filename, 'rb') as f:
 calibrated_state = f.read()
print('read', len(calibrated_state), 'bytes on file', state_filename)
# Restore
bme680.set_state(calibrated_state)

Calibrate the BME680 and BSEC

Development