Hi Sascha,

if you want a cheap solution, use software UART.
If you think you already on the end of CPU time, try faster crystal.

If you tell us your UART requirements (baud rate, full or half duplex, receive or transmit only, .. ) and what is your routine, which gulp down the CPU time excessively, we can decide, if software UART possible or not.

Otherwiese you must use bigger derivates or SPI UART expanders (e.g. MAXIM). But this was not cheap.


Peter