Boot Communication Channels

The Boot Communication Channels (BCC0 and BCC1) consist of a pair of registers with associated handshake logic, accessible by both CPU and debugger with no security restriction. The registers are intended to communicate with the CPU while executing the Boot ROM which implements security and failure analysis commands and therefore must not be used for another purpose.

Note: The BCC0 and BCC registers values are not reset except in case of POR or BOD resets.

Two Boot Communication Channel status bits in the Status B registers (STATUS.BCCDx) indicate whether a new value has been written in BCC0 or BCC1. These bits, BCCD0 and BCCD1, are located in the STATUSB registers. They are automatically set on write and cleared on read.

Note: The DCC0 and DCC1 registers are shared with the BCC0 and BCC1 registers therefore using DCC is not recommended while the Boot ROM is being executed.