The BREAK character is used to reset the internal state of the UPDI to the default setting. This is useful if the UPDI enters an error state due to a communication error, or when the synchronization between the debugger and the UPDI is lost.
A single BREAK character is enough to reset the UPDI, but in some special cases where the BREAK character is sent when the UPDI has not yet entered the error state, a double BREAK character might be needed. A double BREAK is ensured to reset the UPDI from any state. When sending a double BREAK it is required to have at least one Stop bit between the BREAK characters.
UPDICLKSEL[1:0] | Recommended BREAK Character Duration |
---|---|
0x1 (16 MHz) | 6.15 ms |
0x2 (8 MHz) | 12.30 ms |
0x3 (4 MHz) - Default | 24.60 ms |