humtemp

Temperature and humidity sensor control for the HUZZAH ESP8266 breakout in micropython.

• Measure temperature and humidity
• Update time and send data to graphite carbon or influx
• Deepsleep between measurements

Sensors

• MAX31820MCR-ND temp sensor
• DHT 22 humidity and temp sensor, Adafruit Industries LLC

Wiring Plan

See ./model.

Notes

• RHT03 is actually DHT22 (chose the wrong one or was was not available at the time)
• Resistors for ADC circuit are mounted standing up but this does not seem to be supported in the breadboard view. So it looks weird.

Default pin assignment:

• DHT22 on 12
• Temp Sensor on pin 13

See configuration.py for options.

Prerequisites

Mostly for the "build" process. Where the script files are stripped down a little.

• python3
• python3 venv
• requirements.txt
• perl (for preprocessing, removing debug log statements)
• mpy_cross
  • https://github.com/micropython/micropython/tree/v1.20.0/mpy-cross
  • make, copy to bin
• micropython v1.20.0 on the esp

source env/bin/activate
pip install -r requirements.txt

Copy mpy_cross into PATH.

Flashing esp

• https://docs.micropython.org/en/latest/esp8266/tutorial/intro.html#intro
• https://micropython.org/download/esp8266/ e.g. v1.20.0 (2023-04-26).bin
• esptool.py --port /dev/ttyUSB0 erase_flash
• esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect 0 esp8266-*.bin

mpy version

Via: utils/mpyversion.py

Example:

mpy version: 6 mpy flags: -march=xtensa

Building and running

Prepare esp with micropython.

After that:

make

• Fill out the created config file
• Connect esp using serial connection (and the configured tty)
• retry

Blink Codes

• 10 times - could not connect to wifi and the network. Going to sleep for a while an retry.
• 8 times - could not fetch initial ntp time. Going to sleep for a while an retry.
• 6 times - OSError occured in main loop. Retrying after a few seconds (with increasing holdoff time).
• 4 times - Exception occured in main loop. Retrying after a few seconds (with increasing holdoff time).

Blinks a lot more when debug is on - so this makes only sense when compiled without debug.

Utility Tools

terminal-loop.sh

Will open a screen session in a loop. It will be closed before flushing the device and opens up again when using enter.

util/clean_esp.sh

Removes all files from the esp.

util/mpyversion.py

Prints the required mpy version for the installed micropython firmware on the esp.

util/smoke-test.py

Call esp.check_fw(), and blink the LED.

util/freespace.sh

Connects to the esp and lists the free flash space.

References

• https://learn.adafruit.com/building-and-running-micropython-on-the-esp8266
• https://docs.micropython.org/en/latest/library/index.html#micropython-specific-libraries
• https://github.com/micropython/micropython
• https://github.com/pfalcon/esp-open-sdk

Improvement Ideas

• configration.py could be created/filled by the user now that we have multiple modules