ESP8266 References and Notes

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M Hightower edited this page May 21, 2021 · 23 revisions

Checklist for boot fails:

write_flash succeeds but the program doesn't run

Some References:

Good Pin Information
- Pin information for Huzzah
- Schematic for Huzzah
ESP8266 Hardware Design Guideline
- GPIO Maximum current I-max
  - Typical output current 6mA (info source origin unknown)
  - Maximum output (source) current from one GPIO pin is 12mA
  - Maximum sink current about 20mA
- The 12mA is the maximum amount of current you can safely pull from the ESP32 - While this is about the ESP32. it has good information about how to think about maximum drive strength vs. current.
ESP8266EX Datasheet - seems to be missing AC Characteristics of the GPIO pins. ☹️
- Here is a very old datasheet with potentially incorrect info. It has some info I cannot find in the current datasheet. ☹️ And also here.
  These older datasheets have an "8.4.3 Digital IO Pads" section which I have not found in any current Espressif documents. It shows an "Input pin capacitance Cpad" of 2pF. That is really low and there is no indication as to how it was measured. I found measuring simple capacitance with a DMM, to be about 75pF from pin-to-ground. Which most likely, is not a valid way to measure the property.
ESP8266 SDK Getting Started Guide Version 3.1
ESP8266 Non-OS SDK API Reference Version 3.0
ESP8266 Reset Causes and Common Fatal Exception Causes
ESP8266 SDK Application Note Firmware Download Protocol
- Among other things, it has the Firmware Image Format.
Expressif's ESP8266 Documents
esp-open-sdk
GPIO Pin tricks for driving multiple LEDs
GPIO Pin tricks Charlieplexing for driving multiple LEDs. 4 pins to drive 12 LEDs
ESP8266 pinout reference and how to use GPIO pins good overview

Pointers to lwIP stuff:

Interesting Arduino ESP8266 Projects:

fauxmoESP (Alexa support via Philips Hue)