Review on HiLetgo PCF8574 PCF8574T IO Expansion Board I/O Expander I2C Evaluation Development Module (2pcs) by Darin Marshall

The address contacts of these boards are permanently connected to ground in the address switch circuit. Attempting to select anything other than ground for the address pins will result in a short circuit to ground. Luckily the trace that does this is present on the back and if you cut with a string knife like in the picture full functionality is restored in 30 seconds of work. Note: Only cut between the jumper pins as shown in the picture, I scratched a bit higher but didn't cut these traces. The problem with this is when they need more than one address. I noticed that this product now shows a red board with dip switches instead of a blue jumper board. It is likely that the red circuit board is working properly. I like how the blue boards are chained together.