I bought several of these SC16IS752 DUART modules on Aliexpress to use with my C8051F340 projects but was dissappointed to find the crystal they came with could not handle baud rates above ~57600. So ... I bought some 29.4912 MHZ crystals swapped out the crystals.
I first used solder wick to get out most of the solder, then gently rocked the large crystal side to side until it came loose. I tested it all the way up to 460800 baud ... works fine !
I am really looking for readily available I2C/SPI - to - 4 UART bridges ... or small 8051/STM8/32 micro development boards with at least 4 hard ware UARTs. My searches haven't turned up anything. Does anyone know of any ?
What I did:
* opened farnell.com in the browser
* did a search for UART
* selected the interfaces chips
* selected "4 UARTs"
And found MAX14830.....and many others within one minute