2

AVR069

8015B-AVR-02/06

2 USB Communication

The communication between the AVRISP mkII and the PC is done through its USB

interface. The USB interface utilizes two bulk endpoints; one IN and one OUT. The

USB descriptors can be found in chapter 6.2.

2.1 Packet Format

The PC sends commands to the AVRISP mkII, which responds with an answer. Each

command will generate an answer.

Both commands and answers can be larger than the maximum packet size for the

bulk endpoints, so a command or answer can be split into several IN/OUT packets. A

short packet indicates the end of a command or answer.

The commands and their respective answers are described in chapter 3.

2.2 USB Driver

In order to communicate with the AVRISP mkII, a driver must be installed on the host

computer. A driver can be written from scratch or by using a driver development kit.

AVR Studio 4 bundles a USB driver licensed from Jungo (www.jungo.com). By

obtaining a license from Jungo, 3rd party software can access the same driver as

AVR Studio. The user can then use both AVR Studio and other tools without

changing drivers.

Note: Firmware upgrades for AVRISP mkII can only be uploaded with the dedicated upgrade

software bundled with AVR Studio. This requires that the driver supplied with AVR Studio to be

installed.

3 Commands

This section describes all commands that can be entered to the AVRISP mkII, and all

the possible responses that each command can give back to the host.

For all commands, the AVRISP mkII 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.

3.1 General Commands

3.1.1 CMD_SIGN_ON

This command returns a unique signature string for the AVRISP mkII with this

implementation of the protocol.

Table 3-1. Command format

Field

Size

Value

Description

Command ID

1 byte

CMD_SIGN_ON

Command id