Technical notes.md

Technical notes

Sensors and actuators

Available sensors and actuators.

Microcontrollers

ESP8266

• Data sheet.

- ESP-01

• Exposes only some pins of the ESP8266.
• Data sheet

- ESP-12E (NodeMCU)

• Exposes all pins of the ESP8266.
• Data sheet
• Pinout
• Random notes
  • The on-board LED is turned on with the value false(!).

- Sonoff Basic

• Its a WiFi smart switch.
• Exposes only some pins of the ESP8266.
• Pinout
• Random notes
  • https://randomnerdtutorials.com/how-to-flash-a-custom-firmware-to-sonoff/
  • The on-board LED is turned on with the value false(!).

ESP32

• Data sheet.
• Read this!

- Widora air

• Exposes all pins of the ESP32
• Data sheet
• Pinout.
• Random notes
  • CP210x USB to UART Bridge VCP Drivers.
  • Continuously rebooting after flashing Espruino on a brand new board can be resolved first flash something using Arduino, then Espruino.
  • The DAC pins do not work in Espruino.

Espruino

• The binaries and scripts to flash our boards are here.
• Random notes
  • The ESP-01 and Sonoff Basic need to connect to the PC with an FTDI cable
  • The new FTDI cable is plug and play
  • Problems installing the prolific driver for the old FTDI cable can be resolved.

Espruino Web IDE

• API reference.
• I created some pretty useful examples.
• Espruino uses modules. We can create a central place to host a shared.js module with settings that all things can use. I added a this to the 'Node-RED' story.
• There are multiple options to run the program when the board starts. The option that works fine for me is the Save on send option Direct to Flash.
• Random notes
  • Code which causes the board not to respond can be erased by clearing all memory, see flashing folder.
  • Error while uploading script: Uncaught Error: Unable to find or create file can be resoled by require('Storage').eraseAll().
  • Reading the state of a digital pin with digitalRead does not always work when the pin is used as an output pin by digitalWrite, resolution: keep track of the current state using a variable.
  • I prefer to edit code in Visual Studio Code, then I upload the code with the Espruino Web IDE. We can also use this. Did not have time to look into it.
  • Nice to try: analogWrite(D5, 0.5, { freq : 1 }) also blinks an LED.

Things

• I did a test to see if a switch could be connected using a long network cable. It works, but does it also work for more complex modules like the DHT-22 (temperature, humidity) or HC-SR04 (ultrasonic sound sensor)? Some references:
  • http://www.home-automation-community.com/temperature-and-humidity-from-am2302-dht22-sensor-displayed-as-chart/
  • https://www.sparkfun.com/datasheets/Sensors/Temperature/DHT22.pdf
  • https://www.tinytronics.nl/shop/nl/spanning-converters/level-converters/spi-i2c-uart-bi-directionele-logic-level-converter-4-kanaals

MQTT

MQTTLens

I run into a lay-out issue when the message payload is JSON. Work around is making the window smaller. :-/

Node-RED