Review on 🔢 KNACRO 8 Digital Display Module: MAX7219 Control, Cascading & Serial IO Port Support by Derrick Lowell

The lack of documentation on this made me scratch my head but I was able to find detailed information on it scattered around the web. Since there is no documentation, you are on your own. So if you don't yet know which components are installed or don't use it as a spare part, you can look for something else that is better documented. The key is in the 74HC595D, of which there are two on the board. These are standard 8-bit serial shift registers. So if you can work with it, you can work with it. There are five pins to connect to your microcontroller including GND and VCC. The other 3 give you access to the clock and digital I/O lines. In general, this is not bad. My main complaint was that the two halves of the display didn't line up properly on the circuit board. I ended up desoldering and re-soldering the LEDs to fit. If you don't like the somewhat wobbly display or don't want to do such soldering work, you would look elsewhere. The one I bought has a red display, not a blue one as stated in the product description. Your mileage may vary.