This is a short video showing Youyeetoo R1, how to connect the UART to the board. I did this video to how how to get the UART Device that some with the R1 working.

You can use GPIO Pins as UART, this is from Youyeetoo Wiki
https://wiki.youyeetoo.com/en/r1/DUuart

To get the device working use the following to, the video is proof

The little connector plugs with the two lines showing up, this connect is next the NFC/ANT. With the colors Red (TX), Black (RX) and Yellow (GND). On the UART Device Connect the Black Wire to TXD, Red Wire to RXD, and Yellow Wire to GDN.

I recommend using Mobaxterm, open session and select serial, from the drop menu select the com7 that show USB-SERIAL CH320, this is the USB to TTL. Now, this is import, the baud speed needs to the 1500000 (That's five zero ), anything less than that the screen output garbage.