The Slave communication logic is very simple Standard Frame Structure The Standard frame is defined as stream of bytes with the structure: Standard Start Flag Frame Contents Checksum Stop Flag In this implementation we use the values: Standard Start Flag Stop Flag Checksum Frame Contents F1 hex (or binary) F2 hex (or binary) 1 byte XOR of all bytes in Frame Contents Binary bytes. This means that almost all of the logic that controls the interaction between the Master and the Slave is in the Master. In other words, frames are not ACKed or NAKed.

Neither are good frames acknowledged at the frame level.

A bad frame is ignored and the receiver does not reply with rejection. A frame contains a checksum so that the receiver can verify the integrity of the data it receives. There are several restrictions that we have adopted that greatly simplify the control logic: The Slave only speaks when responding to a specific request from the Master, except under specific, well-defined circumstances that are defined later in this document. CSAFE Protocol Framework 2.1 Frame Based Protocol Communication between the Master and the Slave is accomplished with a simple frame protocol that is easy to implement on a microcontroller yet is quite robust and versatile.

Csafe Protocol Software