bluebottle -- a C library for bit-banging TTL async serial communication.

This is useful if you have an inexpensive microcontroller (such as an ATtiny85) that does not have built-in hardware support for asynchronous serial IO, or the pins with hardware support are already being used for another function.

Currently assumes that bytes are sent least-signicant bit first (LSB), with 8 data bits, no parity bits, and 1 stop bit (8N1), as is relatively common. (A future version may include those, with an interface change to the configuration structs.) Note that the bluebottle struct is exported to allow static allocation, but its existing layout should not be relied upon.

This library factors out timing entirely - if you're sending/receiving at 9600 baud, you'll need to call bluebottle_write_step and/or bluebottle_read_sink 9,600 times per second, with as little variation in timing as your hardware can manage, or you'll get corruption. Be sure to use a crystal whose frequency is a multiple of your baud rate, e.g. 9.6 MHz, 12.96 MHz, or 15.36 MHz for 9600 baud.