Datasheet

4
AVR068
2591C-AVR-06/06
5 Commands
STK500 commands are sent in the MESSAGE_BODY part of a message (see
chapter
2). This section describes all commands that can be entered to the STK500,
and all the possible responses that each command can give back to the host.
In general, all programming modes use the same protocol commands, but various
parameters are sent with the different programming modes in order to avoid
unnecessary overhead in the protocol layer.
For all commands, the STK500 will return an answer with an answer ID that is equal
to the command ID. The first byte in a command is always the command ID, the first
byte in an answer is always the answer ID.
5.1 General Commands
These commands are not related to a specific programming mode.
5.1.1 CMD_SIGN_ON
This command returns a unique signature string for the STK500/AVRISP with this
implementation of the protocol. The signature is “STK500_2” or “AVRISP_2”.
Table 5-1. Command format
Field Size Values Description
Command ID 1 byte CMD_SIGN_ON Command id
Table 5-2. Answer format if target is an STK500
Field Size Values Description
Answer ID 1 byte CMD_SIGN_ON Answer id
Status 1 byte STATUS_CMD_OK
Signature length 1 byte 8 Length of signature string
8 bytes “STK500_2”
The signature string (not
null-terminated)
Table 5-3. Answer format if target is an AVRISP
Field Size Values Description
Answer ID 1 byte CMD_SIGN_ON Answer id
Status 1 byte STATUS_CMD_OK
Signature length 1 byte 8 Length of signature string
8 bytes “AVRISP_2”
The signature string (not
null-terminated)