I have just finished assembling the 737 MCP. Before starting programming I did a test connecting the Arduino boards via USB. This brought power to the boards and therefore I thought that all the 8 digits displays should light up. 4 out of 5 displays did, but the fifth did not.
My question is: Is it right of me to assume that these displays should light up when I connected the USB, or will this display light up when I start programming the boards?
Thanks for all the answers. Mobiflight next!
Hello,
Do not trust the MAX7219 boards to perform anything without mobiflight intialisation. They will randomly come on and off as they are plugged in. Even touching the PCB at the back while powered on will cause them to display random leds.
The true test would be to config the pins in device setup up with mobi and then press test on each of the boards and ensure they display 1-8.
Kind Regards, Karl
Are you using the boards similar to what Karl shows on the website?
https://www.737diysim.com/copy-of-wiring-led-s-to-arduino-1
Maybe try swapping the order of the 7seg displays to check if you have a bad 7-seg or a wiring issue with the connector. Maybe add a picture on how it's connected.
It may be a programming issue. I would write a test application first to check all digits. I believe the driver on the board remembers last display before it was powered off.