"Bit banging" by itself, as a term, does not imply any type of alogorithm, protocol, or interface. The term comes from using software to change the values of bits in bytes or in ports in order to get the bits to change values. Anything "bit banged" has the pretense that it is being "done by hand" in a manual fashion. This "done by hand" implementation is at the hand of the programmer that wrote the program to manipulate the bits in such manner so as to implement some algorithm, protocol, or interface.

It is common, as mentioned earlier, to see "bit banged" software solutions for simple serial inteface protocols. It is most applicable for use in these cases when the serial protocol is a clocked protocol where absolute timing rate is not critical.

Another example of "bit banging" is to consider the implementation of the typical "slow CRC" algorithm wherein bit level code implements the CRC shifting and XOR operations.

In the earliest days of microcontrollers the 8051 was always considered one of the best for implementing "bit banging" because of its rich bit manipulation feature set. Many other early 8-bit microprocessors did not have any direct bit manipulation instructions at all. Then I can recall several microprocessor architectures where bit set and bit clear instructions were added but the added instructions took more code bytes and more run time cycles than equivalent AND with mask or OR with mask instructions!!!

Michael Karas