This section outlines the general frame format used by all sub-protocols.
The protocol handler ID field identifies which sub-protocol to decode the packet by, and this which command handler to forward the packet to.
In general, ID == 0x00 is used as a “query” function in order for
the host to “discover” the feature set of the tool.
Table 44. Command frame format
| Field | Size | Value |
|---|---|---|
| SOF | 1 byte | 0x0E |
| Protocol version | 1 byte | 0x00 in this version (all packets) |
| Sequence ID | 2 bytes | Incrementing from 0x00 (least significant byte sent first) |
| Protocol handler ID | 1 byte | Destination sub-protocol handler ID |
| Payload | N bytes | Data |
Table 45. Response frame format
| Field | Size | Value |
|---|---|---|
| SOF | 1 byte | 0x0E |
| Sequence ID | 2 bytes | Echo of incoming ID (least significant byte sent first) |
| Protocol handler ID | 1 byte | Source sub-protocol handler ID |
| Payload | N bytes | Data |
Table 46. Event frame format
| Field | Size | Value |
|---|---|---|
| SOF | 1 byte | 0x0E |
| Protocol version | 1 byte | 0x00 in this version (all packets) |
| Sequence ID | 2 bytes | Incrementing from 0x00 (least significant byte sent first) |
| Protocol handler ID | 1 byte | Source sub-protocol handler ID |
| Payload | N bytes | Data |
The protocol handler ID field identifies which sub-protocol to decode the packet by, and this which command handler to forward the packet to.
In general, ID == 0x00 is used as a “query” function in order for
the host to “discover” the feature set of the tool.
If there is a condition where the EDBG AVR command handler expects more data
for a command than is available, then the next incoming command will be rejected and an
error response (RSP_FAILED with failure code
FAILURE_USB_PREVIOUS_UNDERRUN) will be returned . Note that such an
underrun situation will result in unknown values for the parameters of the failing
command and the host will have to do the necessary cleanup to undo any undesired
behaviour. The underrun error reporting is done by transport layer and is independent of
the sub-protocol being used.
