One reason I like the SiLabs parts is that most of these have some on-board XDATA. It can be quite nice to be able to use this XDATA to achieve UART FIFO buffers that are in the 256 byte size or larger. If performance is particularly important I will put the FIFO management index variables into the local DATA space so that access to them is efficient and each access to the FIFO would only require one DPTR type addressing to the XDATA area.

For 96% of the embedded applications that I have done where serial communications have been involved, particularly to a PC, I have found zero need to use printf type output routines. It is far more efficient to send values as binary in some type of packet and then let the far end format the data for consumption. If there is a need for formatted data such as when talking to some types of instruments that use old fashioned ASCII type command interfaces then I'll use sprintf() and format in small buffers for the strings that are sized as needed.

Michael Karas