AXE300 Grove Displays


New Member
I am having some problems trying to get some Grove displays to work with Blockly.

I can get the 4 digit display to work OK but I am having problems with the OLED and the LCD RGB displays.

The OLED does not show anything - I have tried two devices and two AXE300.

The RGB display lights blue but all pixels are dark. If you vary the viewing angle, then the message can just be seen as there is a slight variation in the shade of the pixels. Again I have tried two displays and two AXE300. I have the most recent version of PE6 which I reinstalled just in case.

Any thoughts?

Thanks for your help.



Senior Member
Daft question, and I apologise in advance...

Have you got the contrast control connected and adjusted? If you can see "something" it suggests they are working, but the contrast is too high or too low.


New Member
The daft questions are always the best!

Doing a search on google, it looks as though the contrast can be adjusted by replacing the SMD resistor R7. I am reluctant to do this as the display works well using Blockly on an Arduino. I suspect that the PICAXE RGB LCD block may not be initialising the display correctly.


Senior Member
At first, I would check the voltage of the power supply.

... may not be initialising the display correctly.
In that case you probably wont be able to read a message.
While at school, we were using several of these devices. They run fine for years. The only problem we encounter is a faulty backlight.


Senior Member
Even sillier question, given that the LCD is mounted to the PCB at manufacture, we can perhaps assume that the contrast circuit is connected. Is the power supply correct? The datasheet for some of the modules suggest 5V, if the supply is incorrect, the contrast will be incorrect - especially if there is no contrast adjustment control.

If you can see a faint message, I would imagine that (almost) everything is working and there must be something silly somewhere.


Technical Support
Staff member
There are several different generations of Grove OLED modules and they all vary slightly. What is the version number of module you are using? It may be necessary to tweak the initialisation code slightly for your version if Grove have changed their OLED brand again. If you email us the Arduino code you have that is working for that module type we can compare (support at picaxe dot com ).

The RGB LCD module is just a poor design as there is no contrast adjuster. We have seen various different contrasts on various modules and try 3.3V, 4.5V and 5V and see which works best. Changing the resistor will also help.
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