projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 8c22a8f5 DE |
1 | Kernel driver ads1015 |
| 2 | ===================== | |
| 3 | ||
| 4 | Supported chips: | |
| 33ffc74f | 5 | |
| 8c22a8f5 | 6 | * Texas Instruments ADS1015 |
| 33ffc74f | 7 | |
| 8c22a8f5 | 8 | Prefix: 'ads1015' |
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9 | |
| 10 | Datasheet: Publicly available at the Texas Instruments website: | |
| 11 | ||
| 12 | http://focus.ti.com/lit/ds/symlink/ads1015.pdf | |
| 13 | ||
| 60c1f31f | 14 | * Texas Instruments ADS1115 |
| 33ffc74f | 15 | |
| 60c1f31f | 16 | Prefix: 'ads1115' |
| 33ffc74f MCC |
17 | |
| 18 | Datasheet: Publicly available at the Texas Instruments website: | |
| 19 | ||
| 20 | http://focus.ti.com/lit/ds/symlink/ads1115.pdf | |
| 8c22a8f5 DE |
21 | |
| 22 | Authors: | |
| 33ffc74f | 23 | Dirk Eibach, Guntermann & Drunck GmbH <eibach@gdsys.de> |
| 8c22a8f5 DE |
24 | |
| 25 | Description | |
| 26 | ----------- | |
| 27 | ||
| 60c1f31f | 28 | This driver implements support for the Texas Instruments ADS1015/ADS1115. |
| 8c22a8f5 | 29 | |
| 60c1f31f | 30 | This device is a 12/16-bit A-D converter with 4 inputs. |
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31 | |
| 32 | The inputs can be used single ended or in certain differential combinations. | |
| 33 | ||
| c0046867 | 34 | The inputs can be made available by 8 sysfs input files in0_input - in7_input: |
| 33ffc74f MCC |
35 | |
| 36 | - in0: Voltage over AIN0 and AIN1. | |
| 37 | - in1: Voltage over AIN0 and AIN3. | |
| 38 | - in2: Voltage over AIN1 and AIN3. | |
| 39 | - in3: Voltage over AIN2 and AIN3. | |
| 40 | - in4: Voltage over AIN0 and GND. | |
| 41 | - in5: Voltage over AIN1 and GND. | |
| 42 | - in6: Voltage over AIN2 and GND. | |
| 43 | - in7: Voltage over AIN3 and GND. | |
| 8c22a8f5 | 44 | |
| c0046867 | 45 | Which inputs are available can be configured using platform data or devicetree. |
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46 | |
| 47 | By default all inputs are exported. | |
| 48 | ||
| 49 | Platform Data | |
| 50 | ------------- | |
| 51 | ||
| 9010624c | 52 | In linux/platform_data/ads1015.h platform data is defined, channel_data contains |
| c0046867 | 53 | configuration data for the used input combinations: |
| 33ffc74f | 54 | |
| c0046867 | 55 | - pga is the programmable gain amplifier (values are full scale) |
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56 | |
| 57 | - 0: +/- 6.144 V | |
| 58 | - 1: +/- 4.096 V | |
| 59 | - 2: +/- 2.048 V | |
| 60 | - 3: +/- 1.024 V | |
| 61 | - 4: +/- 0.512 V | |
| 62 | - 5: +/- 0.256 V | |
| 63 | ||
| c0046867 | 64 | - data_rate in samples per second |
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65 | |
| 66 | - 0: 128 | |
| 67 | - 1: 250 | |
| 68 | - 2: 490 | |
| 69 | - 3: 920 | |
| 70 | - 4: 1600 | |
| 71 | - 5: 2400 | |
| 72 | - 6: 3300 | |
| 73 | ||
| 74 | Example:: | |
| 75 | ||
| 76 | struct ads1015_platform_data data = { | |
| c0046867 DE |
77 | .channel_data = { |
| 78 | [2] = { .enabled = true, .pga = 1, .data_rate = 0 }, | |
| 79 | [4] = { .enabled = true, .pga = 4, .data_rate = 5 }, | |
| 80 | } | |
| 33ffc74f | 81 | }; |
| 8c22a8f5 | 82 | |
| c0046867 DE |
83 | In this case only in2_input (FS +/- 4.096 V, 128 SPS) and in4_input |
| 84 | (FS +/- 0.512 V, 2400 SPS) would be created. | |
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85 | |
| 86 | Devicetree | |
| 87 | ---------- | |
| 88 | ||
| c0046867 DE |
89 | Configuration is also possible via devicetree: |
| 90 | Documentation/devicetree/bindings/hwmon/ads1015.txt |