I have been playing around trying to create my own controller and the setup includes a 16×2 lcd display wired up to an arduino pro mini. When it is connected to the FTDI cable the lcd displays everything as I expect, however if I then power it from a battery it just display rubbish (some normal characters, some non-ascii characters) if I input data (flip switches etc) the rubbish characters do change so I am guessing the code on the arduino is still running but the display jst seems out of sync.
It did work at one point but then just stopped, I have tried resetting the pro mini many, many times and I also tried changing the serial rate but that didn’t have any effect either.
Anyone have any idea how to get the display back in sync? or why the power from the battery would be different?
When you say you are powering it from the battery, what pins are you actually connecting to Vcc or Vin? Also what voltage is the battery? I’m just wondering if the voltage might be too low for the LCD as the Arduino could operate easily at 3.3V but the LCD might be struggling to recognise input voltages that low. Your FTDI cable would be giving a constant 5V on directly to the Vcc pin. Have you measured the voltage on the LCD Vcc pin when you are connected to the battery?
Yes I taught you might have been using less than 5V, I think I tried to power one from 3.3V a few years back and it didn’t initialize at all and someone told me they are pretty much 5V only. I was using a 7.4 Volt lipo through the Arduino Uno Vin pin to power the LCD shield before so that works if you have one of those.