https://github.com/luxedo/rpi_mcp3008

RPi_mcp3008 is a library to listen to the MCP3008 A/D converter chip, as described in the datasheet.
https://github.com/luxedo/rpi_mcp3008

analog-digital-communication gpio mcp3008 python python-library raspberry-pi rpi spi wiring

Last synced: 2 months ago
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RPi_mcp3008 is a library to listen to the MCP3008 A/D converter chip, as described in the datasheet.

• Host: GitHub
• URL: https://github.com/luxedo/rpi_mcp3008
• Owner: luxedo
• License: gpl-3.0
• Created: 2015-11-20T21:43:59.000Z (about 9 years ago)
• Default Branch: master
• Last Pushed: 2024-06-18T02:13:25.000Z (6 months ago)
• Last Synced: 2024-10-11T02:03:01.937Z (2 months ago)
• Topics: analog-digital-communication, gpio, mcp3008, python, python-library, raspberry-pi, rpi, spi, wiring
• Language: Python
• Homepage: https://pypi.org/project/mcp3008/
• Size: 36.1 KB
• Stars: 8
• Watchers: 2
• Forks: 6
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE.md

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README

        
# RPi_mcp3008

RPi_mcp3008 is a library to listen to the MCP3008 A/D converter chip with a RPi.

This library implements the example communication protocol described in the [datasheet](https://www.adafruit.com/datasheets/MCP3008.pdf).

Communication is made through RPi SPI port using [SpiDev](https://github.com/doceme/py-spidev)

## Wiring

Connect the SPI data cables in the tables below. Choose either CE0# or CE1# to connect to CS.

### RPi SPI GPIOs

| RPi GPIO  | Mode |

|-----------|:-----|

| GPIO 07   | CE1# |

| GPIO 08   | CE0# |

| GPIO 09   | MISO |

| GPIO 10   | MOSI |

| GPIO 11   | SCLK |

### MCP3008 Pinout

| Pin | Description | Pin | Description |

|-----|:------------|:----|:------------|

| 01  |     CH0     | 09  | Vdd - Supply voltage (2.7V - 5.5V) |

| 02  |     CH1     | 10  | Vref - Reference voltage |

| 03  |     CH2     | 11  | AGND - Analog ground |

| 04  |     CH3     | 12  | CLK - SPI Clock (SCLK) |

| 05  |     CH4     | 13  | Dout - Data out (MISO) |

| 06  |     CH5     | 14  | Din - Data in (MOSI) |

| 07  |     CH6     | 15  | CS - Chip select (CE0# or CE1#) |

| 08  |     CH7     | 16  | DGND - Digital ground |

Please check the [Adafruit guide](https://learn.adafruit.com/reading-a-analog-in-and-controlling-audio-volume-with-the-raspberry-pi/connecting-the-cobbler-to-a-mcp3008) on the MCP3008 for more information about wiring

## Usage

RPi_mcp3008 uses the `with` statement to properly handle the SPI bus cleanup.

```python

import mcp3008

with mcp3008.MCP3008() as adc:

    print(adc.read([mcp3008.CH0])) # prints raw data [CH0]

```

It's possible instantiate the object normally, but it's necessary to call the close method before terminating the program.

```python

import mcp3008

adc = mcp3008.MCP3008()

print(adc.read([mcp3008.CH0])) # prints raw data [CH0]

adc.close()

```

The initialization arguments are `MCP3008(bus=0, device=0, max_speed_hz=976000)` where:

`MCP3008(X, Y)` will open `/dev/spidev-X.Y`, same as `spidev.SpiDev.open(X, Y)`

Both arguments are optional and have a default value of `0`.

The default max SPI driver speed is 976 kHz.

### Methods

Currently there are two implemented methods:

```python

def read(self, modes, norm=False):

    '''

    Returns the raw value (0 ... 1024) of the reading.

    The modes argument is a list with the modes of operation to be read (e.g.

    [mcp3008.CH0,mcp3008.Df0]).

    norm is a normalization factor, usually Vref.

    '''

```

```python

def read_all(self, norm=False):

    '''

    Returns a list with the readings of all the modes

    Data Order:

    [DF0, DF1, DF2, DF3, DF4, DF5, DF6, DF7,

     CH0, CH1, CH2, CH3, CH4, CH5, CH6, CH7]

    norm is a normalization factor, usually Vref.

    '''

```

* The `modes` argument must be a list with at least one of 16 modes listed below

* The `norm` argument is a normalization factor that rescales raw data, usually Vref

### Fixed mode

You can also declare the class with a `fixed mode`, which will make the instance callable and always return the value of the listed modes.

Again you can normalize the data with the norm argument when calling the instance.

```python

import mcp3008

with mcp3008.MCP3008.fixed([mcp3008.CH0, mcp3008.DF0]) as adc:

    print(adc())     # prints raw data [CH0, DF0]

    print(adc(5.2))  # prints normalized data [CH0, DF0]

```

## MCP3008 Operation Modes

MCP3008 has 16 different operation modes:

It can listen to each of the channels individually **Single Ended** or in a pseudo-differential mode **Differential**

| Single Ended | Differential |

|--------------|:-------------|

| CH0  | DF0  (CH0 = IN+; CH1 = IN-) |

| CH1  | DF0  (CH0 = IN-; CH1 = IN+) |

| CH2  | DF0  (CH2 = IN+; CH3 = IN-) |

| CH3  | DF0  (CH2 = IN-; CH3 = IN+) |

| CH4  | DF0  (CH4 = IN+; CH5 = IN-) |

| CH5  | DF0  (CH4 = IN-; CH5 = IN+) |

| CH6  | DF0  (CH6 = IN+; CH7 = IN-) |

| CH7  | DF0  (CH6 = IN-; CH7 = IN+) |

Use the table above as the operation mode when calling `MCP3008.read(modes)` or setting the `MCP3008.fixed(modes)` mode. (e.g. `MCP3008.read([mcp3008.CH0, mcp3008.DF1])`)