I spent a day debugging a buffer doing its job
My ADC read random, noisy values run to run; there was no bug — with the high-impedance buffer enabled and nothing connected, I was watching input bias current charge the amplifier’s input impedance.
Troubleshooting
Good Enough to Move On: Patching an ADS1255 Driver.
I started from someone else’s ADS1255 driver, fixed the original’s mistakes and a few of my own, added some quality-of-life features, and stopped the moment it was good enough to get back to testing the ADC.