I have a clock program I thought it worked well until I hard mounted everything. now that I can leave it running I have endless problems with corrupted or locked up displays. It runs about 36 hours, then locks up or shows random characters.
the displays that lock up are driven with sprintf. sometimes the backlight turns off. I was using 2 16X2s. I moved those functions to one 20X4. same results
The cable is about 3 feet long. 4.7 K pullup resistors at the terminal board on the 5 display panel, in common with all displays. I have an I2C buffer module coming.
Is this related to sprintf, or just a coincidence?
somebody is going to say publish the program. It's 9 k. it uses a particular library and a particular I2C backpack. if I post it, one of our perennial fault finders will jump in. so, no, thank you.