Arduino, ESP and i2c devices

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This project permits to control a remote LCD display connected via an i2c port expander via Wifi.

I have successfully tested this program on an ESP-12 (ESP8266) using the Arduino IDE.

hardware

The hardware "ingredients" needed for this experiments are:

  • a ESP8266 (in the example it is a ESP12).
  • an lcd-plug by jeelabs including the display
  • A "console cable" (but any USB to TTL converter is okay).

wiring

i2c: SDA is GP04, SCL is GP05. The pins of jeelabs' lcd plug (this cabling works for all i2c based jeelabs' plugs):

  • P -> +5V or disconnected (unused for lcd-plug)
  • D -> GP04 (SDA)
  • G -> GND
  • + -> +3V3
  • A -> GP05 (SCL)
  • I -> NC (unused for lcd-plug, can be connected to another GPIO for other boards providing useful interrupts).

Console cable: using an Adafruit like cable:

  • Black -> GROUND
  • While -> TXD on ESP
  • Green -> RXD on ESP

DO NOT CONNECT THE RED PIN TO YOUR ESP! The red pin is +5V while ESP need +3V3 so either you have a step-down circuit to convert 5V to 3.3V or you'll need another power source of the right voltage for yout ESP.

Software

Here is the source code.

Testing

Load the program on you ESP. Remember that GP00 must be connected to ground at power-up to set the ESP in "flashing mode".


Unplug GP00 otherwise at the next power cycle your ESP will be in "flashing mode" again. If GP00 is unconnected, the program is restarted at power up.

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