ESP8266 displaying mqtt messages on a Nokia 5110 LCD

I'm pulling in several git subtree modules :

• tuanpmt's exellent mqtt project: esp_mqtt
• esp8266_pcd8544 the lcd driver
• esp8266_easygpio makes it easy to change GPIO pins
• esp8266_stdout alternative UART implementation (required if you want to connect the lcd with only 3 pins)

Good news, the interface no longer requires 5 available GPIO outputs so an ESP-01 will indeed work. (But only if the RX pin of the esp is used.)

##Usage To use this mqtt enabled LCD you can send text messages to these topics:

• /lcd0
• /lcd1
• /lcd2
• /lcd3
• /lcd4
• /lcd5

Representing each row of the display.

The LCD is also listening to these topics:

• /lcd/clearscreen
• /lcd/contrast

You can also send messages to topics that are unique to each esp, look at the debug console for more info.

This is how the code is hooked up by default:

Some ESP-12 have GPIO4 & GPIO5 reversed.

The RST pin is optional, set it to a negative value and tie PCD8544 reset to ESP reset via a resistor.

The CE pin is optional, set it to a negative value and tie PCD8544 CE pin to GND via a resistor.

All of the pins are configurable, you just set the pins you want to use in the setting struct.

The makefile is copied from esp_mqtt.

###Building and installing:

First you need to install the sdk and the easy way of doing that is to use esp_open_sdk.

You can put that anywhere you like (/opt/local/esp-open-sdk, /esptools etc etc)

Then you could create a small setenv.sh file, containing the location of your newly compiled sdk and other platform specific info;

export SDK_BASE=/opt/local/esp-open-sdk/sdk
export PATH=${SDK_BASE}/../xtensa-lx106-elf/bin:${PATH}
export ESPPORT=/dev/ttyO0  

(or setup your IDE to do the same)

You will have to edit the include/user_config.h file to suit your WiFi and mqtt settings. Alternatively you can copy include/user_config.h into localinclude/user_config.h and git will not bother you about modified files.

To make a clean build, flash and connect to the esp console you just do this in a shell:

source setenv.sh # This is only needed once per session
make clean && make test

You won't be needing esptool, the makefile only uses esptool.py (provided by esp-open-sdk)

I have tested this with sdk 1.5.2, v0.9.5 and v0.9.4 (linux & mac)