User adjustable baud, bit, and stop bit settings

I have an electronic circuit that records serial data into an internal memory, which can be accessed via an attached bluetooth transmitter. The serial devices that supply the data follow an Asynchronous based serial protocol similar to the RS232 port on a PC, using TTL logic levels. The problem however is that I plan to use different serial devices each having different baud, bit, and stop bit settings. Hence I need the program modified to accept different settings. The program that controls the circuit is running on an ATTiny2313 chip and is written in assembler (source code will be provided)