The emonGLCD is an open-source general purpose wireless graphical LCD display unit. Powered by an Atmega328 which is Arduino compatible. 


The emonGLCD features a 128x64 GLCD display based on the ST7565 driver. The board has an on-board HopeRF RFM12B wireless module to receive data from the emonTx energy monitoring node or an emonBase (web-connected base station)







Current emonGLCD firmware examples: 

Single CT energy monitoring 

Solar PV monitoring 

In current application examples the emonGLCD obtains the current time from the internet via the emonBase. As well as being a useful thing to display the emonGLCD needs to know the current time so it knows when to reset the Kwh counters (at midnight). The emonGLCD also transmits the temperature from its on-board sensor back to the emonBase for posting online emoncms. Read a blog post on how this features work:


emonGLCD demo 


1. Build an emonGLCD

Pictorial step-by-step assembly guide

2. Software: Arduino Sketch Examples

All emonGLCD firmware examples are up on github:

Uses Arduino GLCD library written by Adafruit and JeeLabs is required (much credit to them for sharing this work):

Upload using 5V FTDI cable and Arduino IDE. Select 'uno' under tools>board in IDE

3. Extend it

Create display graphics 

See forum thread for python tool to create glcd graphics from a bitmap: 

RF Signal Strength Meter Scanner by Martin Roberts:

see forum thread

Touchscreen: Nathan Chantrell has been been doing some awesome experimenting with a DS resistive touchscreen layer and RGB PWM backlight. Even a simple touch screen makes menu navigation a doodle. The work is still in development.

Checkout his video of it in action here  and check out the source code here

Good tutorial on interfacing a DS touch screen with an Arduino:

Like the emonTx the emonGLCD has got a JeePort enabling it it be expanded with JeeLabs shields. A useful expansion could be a memory plug for caching large amounts of text and graphics.

A workaround for temperature measurement higher than it should:

The v1.4 PCB contains a track error, rendering the spare Digital IO pin on the JeePort unusable. It can be fixed with a scalpel, see


Port Map

Function emonGLCD V1.2 (old) emonGLCD V1.3+
Push button(s) Dig15 / ADC Dig 15 (enter), dig 16 (up) and dig 19 (down) - requires software pull-up, active low (V1.3 only). Blog post
Temperature sensor Dig 5 Dig 5
LDR light sensor ADC0 – see V1.2 bugs page ADC4
Tri-color LED Red Dig 9 – PWM Dig 9 – PWM
Tri-colour LCD Green Dig 8 Dig 6 – PWM

 emonGLCD V1.4 schematic and changes: emonGLCD v1.4 schematic

Please contribute any cool example you write! This page is an open wiki (once logged in). 



emonGLCD Schematic and board files up on solderpad 

emonGLCD Fascia CAD design is up on Thingiverse

Based on design. 


Revision track 

V1.2 - first release 

V1.3 - 

  • LDR moved to ADC4,
  • LED from Dig 8 to Dig 6 to be on PWM output
  • Added two extra push buttons for menu navigation (Dig 16 and Dig19) - don't work. Update: they do work!
  • Connected backlight directly to IRQ PWM
  • Added two additional menu selection buttons to make three in total

V1.4 - 

  • Fixed switches connections 
  • Connected LCD to 3.3V instead of 5V
  • External power connection now routed through voltage reg - accepts input from 5-12V


  • Corrected orientation of C13 and C14, this fixed issue of LCD contrast fading when

Ideas for the future:

  • Built lithium in battery pack + usb charging circuit? 
  • Female headers to attach LCD
  • Change LCD module to a more mainstream and lower cost unit
  • RGB PWM backlight
  • SMT components pre assembled 



Creative Commons License
The emonGLCD hardware deisgnes (schematics and CAD files) are licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

The emonGLCD firmware is released under the GNU GPL V3 license

The documentation is subject to GNU Free Documentation License 

The emonGLCD hardware designs follow the terms of the OSHW (Open-source hardware) Statement of Principles 1.0.

Open-source hardware (OSHW) logo

What this basically means is that you are free to modify, re-distribute and use the design in a personal or commercial environment as long as you attribute OpenEnergyMonitor and make any resulting designs or derivatives available under the same open-source licenses. Read more about open-source...

If you use the emonGLCD design, please consider donating (see bottom of page) to the OpenEnergyMonitor project to help fund ongoing open-source developments. Thank you. 

If you have any questions about the emonGLCD, please post in our hardware forum.