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Documentation / leds / leds-lm3556.txt




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Based on kernel version 3.13. Page generated on 2014-01-20 22:03 EST.

1	Kernel driver for lm3556
2	========================
3	
4	*Texas Instrument:
5	 1.5 A Synchronous Boost LED Flash Driver w/ High-Side Current Source
6	* Datasheet: http://www.national.com/ds/LM/LM3556.pdf
7	
8	Authors:
9		Daniel Jeong
10		Contact:Daniel Jeong(daniel.jeong-at-ti.com, gshark.jeong-at-gmail.com)
11	
12	Description
13	-----------
14	There are 3 functions in LM3556, Flash, Torch and Indicator.
15	
16	FLASH MODE
17	In Flash Mode, the LED current source(LED) provides 16 target current levels
18	from 93.75 mA to 1500 mA.The Flash currents are adjusted via the CURRENT
19	CONTROL REGISTER(0x09).Flash mode is activated by the ENABLE REGISTER(0x0A),
20	or by pulling the STROBE pin HIGH.
21	LM3556 Flash can be controlled through sys/class/leds/flash/brightness file
22	* if STROBE pin is enabled, below example control brightness only, and
23	ON / OFF will be controlled by STROBE pin.
24	
25	Flash Example:
26	OFF     : #echo 0 > sys/class/leds/flash/brightness
27	93.75 mA: #echo 1 > sys/class/leds/flash/brightness
28	... .....
29	1500  mA: #echo 16 > sys/class/leds/flash/brightness
30	
31	TORCH MODE
32	In Torch Mode, the current source(LED) is programmed via the CURRENT CONTROL
33	REGISTER(0x09).Torch Mode is activated by the ENABLE REGISTER(0x0A) or by the
34	hardware TORCH input.
35	LM3556 torch can be controlled through sys/class/leds/torch/brightness file.
36	* if TORCH pin is enabled, below example control brightness only,
37	and ON / OFF will be controlled by TORCH pin.
38	
39	Torch Example:
40	OFF     : #echo 0 > sys/class/leds/torch/brightness
41	46.88 mA: #echo 1 > sys/class/leds/torch/brightness
42	... .....
43	375 mA  : #echo 8 > sys/class/leds/torch/brightness
44	
45	INDICATOR MODE
46	Indicator pattern can be set through sys/class/leds/indicator/pattern file,
47	and 4 patterns are pre-defined in indicator_pattern array.
48	According to N-lank, Pulse time and N Period values, different pattern wiill
49	be generated.If you want new patterns for your own device, change
50	indicator_pattern array with your own values and INDIC_PATTERN_SIZE.
51	Please refer datasheet for more detail about N-Blank, Pulse time and N Period.
52	
53	Indicator pattern example:
54	pattern 0: #echo 0 > sys/class/leds/indicator/pattern
55	....
56	pattern 3: #echo 3 > sys/class/leds/indicator/pattern
57	
58	Indicator brightness can be controlled through
59	sys/class/leds/indicator/brightness file.
60	
61	Example:
62	OFF      : #echo 0 > sys/class/leds/indicator/brightness
63	5.86 mA  : #echo 1 > sys/class/leds/indicator/brightness
64	........
65	46.875mA : #echo 8 > sys/class/leds/indicator/brightness
66	
67	Notes
68	-----
69	Driver expects it is registered using the i2c_board_info mechanism.
70	To register the chip at address 0x63 on specific adapter, set the platform data
71	according to include/linux/platform_data/leds-lm3556.h, set the i2c board info
72	
73	Example:
74		static struct i2c_board_info board_i2c_ch4[] __initdata = {
75			{
76				 I2C_BOARD_INFO(LM3556_NAME, 0x63),
77				 .platform_data = &lm3556_pdata,
78			 },
79		};
80	
81	and register it in the platform init function
82	
83	Example:
84		board_register_i2c_bus(4, 400,
85					board_i2c_ch4, ARRAY_SIZE(board_i2c_ch4));
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