ESP8266/Arduino/PlatformIO Demos

This project's branches contain several different ESP8266 + Arduino demos, built using PlatformIO, for the Wemos D1 Mini board:

• Branch basic-wifi connects to a WiFi network and then periodically pings Google
• Branch influxdb reports ping results and WiFi statistics to an InfluxDB server periodically
• Branch https performs GET and POST requests over HTTPS, using JSON and performing proper TLS certificate verification using a root store
• Branch letsencrypt performs a GET over HTTPS, performing proper TLS certificate verification using a small set of root certificates (Let's Encrypt's roots)

My goals for this project are:

• Learn about this platform for myself; get good enough at it to do hobby projects.
• Provide some good examples using what I think are best practices, since a lot of tutorial/demonstration Arduino code available online is not very good.

In particular, I'd like to note:

• I felt it was important to provide reliable feedback via blinking the onboard LED, which also provides a demonstration of using timer interrupts.
• I demonstrate some basic usage of a cooperative multitasking scheduler for Arduino.
• These demo projects make the board show up as a .local domain on the network using multicast DNS.
• Contrary to code from the majority of Ardunio/ESP8266 HTTPS tutorials & forums, my HTTPS demo project fetches the current time and loads a certificate root store, allowing for secure and flexible TLS certificate validation.

Notable third-party open-source libraries demonstrated:

• InfluxDB client for Arduino
• ArduinoJSON

Blog posts for these demos will eventually be posted at dzombak.com/blog. Thus far:

• ESP8266 + PlatformIO Serial Console Monitoring with Exception Decoding (October 7, 2021)
• Debugging an Intermittent Arduino/ESP8266 ISR Crash (October 7, 2021)
• Reusing an ESP8266HTTPClient (October 8, 2021)
• How to enable debug logging for Arduino's ESP8266HTTPClient with PlatformIO (October 8, 2021)
• Initial Impressions of ESP8266 + Arduino (October 15, 2021)
• Shipping Data to InfluxDB using Arduino + ESP8266 (October 15, 2021)
• HTTPS Requests with a Root Certificate Store on ESP8266 + Arduino (October 28, 2021)
• HTTPS Requests with a Small Set of Root Certificates on ESP8266 + Arduino (October 29, 2021)