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-   -   Getting started with MPGuino. Need help with weird display. (

peifferu 06-26-2015 06:11 AM

Getting started with MPGuino. Need help with weird display.
Arduino uno, spark fun LCD, v0.86 (not sure what info you'll need to know).
Anyway I've been troubleshooting display issues and haven't gotten far. After power cycles, different editions of code, and double checking wiring, my display shows "Contrast, 000000000055 OK XX" and the LCD backlight and led from the transistor occasionally turn off and on. I can't make it change screens or anything with the buttons. What do I need to do? Thanks in advance!

AndrzejM 07-06-2015 08:36 AM


That's a strange issue...
Let me know what diagram exactly have you used to build your MPGuino - there are few of these... Maybe some photos of the setup?
I'll do my best to help you.

peifferu 07-06-2015 08:54 AM

Thanks for the response! I actually got the main issue figured out: my buttons were connected sideways so they were effectively always closed. I still have an issue with the backlight. Changing the brightness doesn't help. It comes on after about 30 seconds and only stays on for a second. It's not a constant interval between blinks. I used the Arduino assembly schematic on the wiki.

AndrzejM 07-06-2015 10:49 AM

It seems that there's something wrong with transistor running current to the backlight.
It's easy to chech if you'll connect LED backlight with 330 ohm resistor to +5V it should be stable. If not it means that there's something wrong with your LCD display. If everything will be ok with resistor, there's something wrong with connection between Arduino and LCD. There's resistor, and transistor only so not hard to find the reason.

And one more question - are you sure that you connected backlight signal to digital 9 ?

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