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1 | Kernel driver ads1015 | ||
2 | ===================== | ||
3 | |||
4 | Supported chips: | ||
5 | * Texas Instruments ADS1015 | ||
6 | Prefix: 'ads1015' | ||
7 | Datasheet: Publicly available at the Texas Instruments website : | ||
8 | http://focus.ti.com/lit/ds/symlink/ads1015.pdf | ||
9 | |||
10 | Authors: | ||
11 | Dirk Eibach, Guntermann & Drunck GmbH <eibach@gdsys.de> | ||
12 | |||
13 | Description | ||
14 | ----------- | ||
15 | |||
16 | This driver implements support for the Texas Instruments ADS1015. | ||
17 | |||
18 | This device is a 12-bit A-D converter with 4 inputs. | ||
19 | |||
20 | The inputs can be used single ended or in certain differential combinations. | ||
21 | |||
22 | The inputs can be made available by 8 sysfs input files in0_input - in7_input: | ||
23 | in0: Voltage over AIN0 and AIN1. | ||
24 | in1: Voltage over AIN0 and AIN3. | ||
25 | in2: Voltage over AIN1 and AIN3. | ||
26 | in3: Voltage over AIN2 and AIN3. | ||
27 | in4: Voltage over AIN0 and GND. | ||
28 | in5: Voltage over AIN1 and GND. | ||
29 | in6: Voltage over AIN2 and GND. | ||
30 | in7: Voltage over AIN3 and GND. | ||
31 | |||
32 | Which inputs are available can be configured using platform data or devicetree. | ||
33 | |||
34 | By default all inputs are exported. | ||
35 | |||
36 | Platform Data | ||
37 | ------------- | ||
38 | |||
39 | In linux/i2c/ads1015.h platform data is defined, channel_data contains | ||
40 | configuration data for the used input combinations: | ||
41 | - pga is the programmable gain amplifier (values are full scale) | ||
42 | 0: +/- 6.144 V | ||
43 | 1: +/- 4.096 V | ||
44 | 2: +/- 2.048 V | ||
45 | 3: +/- 1.024 V | ||
46 | 4: +/- 0.512 V | ||
47 | 5: +/- 0.256 V | ||
48 | - data_rate in samples per second | ||
49 | 0: 128 | ||
50 | 1: 250 | ||
51 | 2: 490 | ||
52 | 3: 920 | ||
53 | 4: 1600 | ||
54 | 5: 2400 | ||
55 | 6: 3300 | ||
56 | |||
57 | Example: | ||
58 | struct ads1015_platform_data data = { | ||
59 | .channel_data = { | ||
60 | [2] = { .enabled = true, .pga = 1, .data_rate = 0 }, | ||
61 | [4] = { .enabled = true, .pga = 4, .data_rate = 5 }, | ||
62 | } | ||
63 | }; | ||
64 | |||
65 | In this case only in2_input (FS +/- 4.096 V, 128 SPS) and in4_input | ||
66 | (FS +/- 0.512 V, 2400 SPS) would be created. | ||
67 | |||
68 | Devicetree | ||
69 | ---------- | ||
70 | |||
71 | Configuration is also possible via devicetree: | ||
72 | Documentation/devicetree/bindings/hwmon/ads1015.txt | ||