原创尼康热靴协议-2

 2012-6-12 17:33  1891 8 8 分类: 消费电子

Detailed Description

Header (first byte in frame)

The header byte (which is always send by the camera) determines whether the camera or the speed light sends the following data and the checksum. The following header bytes are known to me:

Table: Command overview
Command (header byte)			Name	Who sends payload?	Payload length without CRC	Checksum seed	Comment
decimal	hex	bin	Name	Who sends payload?	Payload length without CRC	Checksum seed	Comment
160d	0xA0	10100000b	Flash_Settings	Flash	21d	1d	Standard frame, flash reports its settings, meaning 90% known
161d	0xA1	10100001b	INIT_0	Flash	17d	1d	first byte after power on, fixed unknown content
162d	0xA2	10100010b	INIT_2	Flash	45d		third byte after power on, fixed unknown content
176d	0xB0	10110000b	Cam_settings	Cam	14d	176d	Standard frame, camera reports its settings, meaning 90% known
177d	0xB1	10110001b	INIT_1	Cam	9d		second byte after power on, unknown content, camera specific
192d	0xC0	11000000b	Postflash	Flash	?		after a main flash the camera queries the speedlight for this data
208d	0xD0	11010000b	AF-ILL	Cam	1d	CRC always 0	enable/disable the AF assist light
209d	0xD1	11010001b	Red_eye	Cam	1d	NA	Send red eye reduction preflashes: Payload 128 start, 0 stop (check)
211d	0xD3	11010011b	Flashpower	Cam	2d	CRC always 211d	set flash power
213d	0xD5	11010101b	Modeling Light	NA	0d	CRC always 213d	enables the modeling light
215d	0xD7	11010111b	Preflash_1	NA	0d	-	first pre-flash, no data, no checksum, special timing on the clock line
216d	0xD8	11011000b	Preflash_2	Cam	1d	-	second pre-flash, no checksum, special timing on the clock line
224d	0xE0	11100000b	Cam_off	?	1d		sends the speedlight to sleep

The command seems to consist of various addressing bits. But so far they don't make any sense. There is no obvious way to tell from a command how many bytes have to be transferred. The only thing I know is that the MSB is always set (i.e. only commands >128d exist) and bit 4 seems o specify the sender of the payload.