Review on 🍓 Raspberry Pi Serial Expansion HAT with SC16IS752, 2-ch UART, 8 GPIOs, and I2C Interface, Stackable up to 16 Modules for 32-ch UART by Ismael Hennigan

Product works well. I was able to load the Raspberry PI overlay and modify the config.txt file in the boot partition. After rebooting, two UART devices appeared. Much of the vendor's customization was unnecessary and outdated for current Raspberry Pi images. Worked fine on Jessie, not sure on new versions. It's worth noting that what I received had connectors and wires for UART connections. Be careful as the wire colors are reversed on the connector than on the PCB. For example Black and Red are not +3.3 but GND is RTS and CTS. I recommend that you swap the wires before using for easier connection to your project. UPDATE 12/21/2020. Attempting to use both UARTs will eventually block both ports. Only a restart solves the problem. Searching the internet I found a topic describing a problem with the driver. Hopefully this gets fixed as it renders the device unusable. UPDATE 12/22/2020. I've tested this with the latest Raspberry PI OS (Buster) and it doesn't lock up in dual channel. Worked for almost 24 hours before being locked for 5 minutes. I recommend.