When âSoftware Bugsâ Are Actually Bad Soldering A quick MLX90640 IR camera test turned into a dead-on-I2C mystery. I ran the usual checksâaddresses, pull-ups, voltages, wiringâand even fixed my forgotten UART/I2C jumper, but still nothing. A peek under the microscope revealed sketchy solder on the 3V3 LDO; a quick reflow and the sensor sprang to life. Lesson relearned: donât trust factory soldering, look early with a microscope, and stop blaming software when the hardwareâs silent. 25 January 2026