USB Protocol

Command Message

		Command Byte
Group	Command Type	0	1	2	3	4
Capture/Control	Capture	Command 0x00	Flash Power 0x00 - 0xff	Expected Size Low 0x00 - 0xff	... 0x00 - 0xff	Expected Size High 0x00 - 0xff
	Slave Capture Rising	Command 0x01	Flash Power 0x00 - 0xff	Expected Size Low 0x00 - 0xff	... 0x00 - 0xff	Expected Size High 0x00 - 0xff
	Reset	Command 0x02	Level 0x00 - 0x01	Null 0x00	Null 0x00	Null 0x00
	Flush	Command 0x03	Null 0x00	Null 0x00	Null 0x00	Null 0x00
	Master Capture	Command 0x04	Flash Power 0x00 - 0xff	Expected Size Low 0x00 - 0xff	... 0x00 - 0xff	Expected Size High 0x00 - 0xff
	Slave Capture Falling	Command 0x05	Flash Power 0x00 - 0xff	Expected Size Low 0x00 - 0xff	... 0x00 - 0xff	Expected Size High 0x00 - 0xff
Registers	Write Register	Command 0x10	Address Low 0x00 - 0xff	Address High 0x00 - 0xff	Value Low 0x00 - 0xff	Value High 0x00 - 0xff
	Write Bit	Command 0x11	Address Low 0x00 - 0xff	Address High 0x00 - 0xff	Bit Index 0x00 - 0x0f	Bit Value 0x00 - 0x01
	Queue Register	Command 0x12	Address Low 0x00 - 0xff	Address High 0x00 - 0xff	Null 0x00	Null 0x00
	Read Register Page	Command 0x13	Page Index 0x00 - 0xff	Null 0x00	Null 0x00	Null 0x00
I/O	Write Device	Command 0x20	Index 0x00 - 0xff	Value 0x00 - 0xff	Null 0x00	Null 0x00
	Queue Device	Command 0x21	Index 0x00 - 0xff	Null 0x00	Null 0x00	Null 0x00
	Initialise Device	Command 0x22	Index 0x00 - 0xff	Configuration 0x00 - 0xff	Null 0x00	Null 0x00
	Write Block	Command 0x23	Index 0x00 - 0xff	Length Low 0x00 - 0xff	... 0x00 - 0xff	Length High 0x00 - 0xff
	Read Block	Command 0x24	Index 0x00 - 0xff	Maximum Length Low 0x00 - 0xff	... 0x00 - 0xff	Maximum Length High 0x00 - 0xff
	Channel	Command 0x25	Index 0x00 - 0xff	Mode 0x00 - 0x01	Channel Low 0x00 - 0xff	Channel High 0x00 - 0xff
	Query	Command 0x2f	Index 0x00 - 0xff	Null 0x00	Null 0x00	Null 0x00

Command Packet

	Header	Control (0..1)	Commands (0..N)		Terminator
Description	Null	Capture/Slave/Reset/Flush	Write/Queue/Initialise	...	0xff
Size (bytes)	5	5	5	...	1

If the command is a "Write Block" then the bytes that follow it are not a 5-byte command block but instead raw data to be written to the device index specified. The length of the raw data is declared in the command.

Flush Response Packet

	Header	Registers (0..N)			Devices (0..N)
Description	Register count	Address	Data	...	Index	Length	Data	...
Size (bytes)	1	2	2	...	1	2	0 - 65k	...

Capture Response Packet

Description	Image data
Size (bytes)	0 - 16M

Register Page Response Packet

Description	Page of registers
Size (bytes)	512

Unlike other data packets in the protocol, the values in the page are high-low byte order and not low-high.

Reset

The reset command 0x02 can trigger different levels of reset:

0x00: Full chip reset
0x01: Communication buffers reset

Query Camera

Device 0xff can be used to query the camera. The layout for the response is as follows:

	Header		Devices
Description	Header size	Header Data	Device count	Index	...
Size (bytes)	1	0-255	1	1	...

If the device flush response is empty (i.e., 0x00 0xff 0x00 0x00) then the default chip configuration and devices are assumed.

Header Data

When querying the device, the header data will contain the following information and can be extended for future use by simply increasing the header size (up to a maximum of 255 bytes).

0: Chip type     -> 0x00 (v024), 0x01 (mt9)
1: Configuration -> bitmask (see below)

Configuration Bitmask

Bit	7	6	5	4	3	2	1	0
Description	Flash mode	Reserved	Reserved	Reserved	Reserved	Reserved	Reserved	Bayer

Device Channels

Channel

A device can have multiple channels and the command 0x25 is used to select which channel to target for configuration, reading and writing.

A mode of 0x00 simply queries the current channel and a mode of 0x01 sets the channel to the supplied index.

Either function will result in the following response from the camera.

0: Channel low
1: Channel high
2: Type ID low
3: Type ID high

Where channel is the current channel and type ID indicates the type of device on that channel.

This allows you to have, for example, a single device index representing temperature sensors. The device then has multiple temperature sensors represented as different channels. Some of the temperature sensors may vary from others and the type ID allows the software to determine which type it is and therefore know how it should communicate with it.

Query

Sending a query command 0x2f will return the following structure.

 0: Index              -> which device was queried
 1: Functionality low  -> bitmask indicating which device functions are supported 0x20 - 0x2f
 2: Functionality high
 3: Channel low        -> number of available channels
 4: Channel high
 5: Reserved 0         -> reserved register for future use
 6: Reserved 1
 7: Reserved 2
 8: Reserved 3
 9: Status 0           -> status flag registers
10: Status 1
11: Status 2
12: Status 3

Channels are always zero-indexed and contiguous, so the last channel available is always N - 1.