https://github.com/scruss/mcp4131

MicroPython module to control MicroChip's MC4131 SPI digital potentiometer
https://github.com/scruss/mcp4131

Last synced: 2 months ago
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MicroPython module to control MicroChip's MC4131 SPI digital potentiometer

• Host: GitHub
• URL: https://github.com/scruss/mcp4131
• Owner: scruss
• License: mit
• Created: 2021-10-06T02:44:12.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2021-10-06T03:11:17.000Z (over 2 years ago)
• Last Synced: 2024-01-27T08:10:33.540Z (5 months ago)
• Language: Python
• Size: 3.91 KB
• Stars: 3
• Watchers: 2
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Lists

• awesome-micropython - mcp4131 - MicroPython module to control MicroChip's MCP4131 SPI digital potentiometer. (Libraries / IO)

README

        
# mcp4131

MicroPython module to control MicroChip's MC4131 SPI digital potentiometer

    from machine import Pin, ADC, SPI

    import mcp4131

    import time

    a = ADC(0)

    cs = Pin(17, Pin.OUT)

    s = SPI(0, sck=Pin(18), mosi=Pin(19), miso=Pin(16))

    m = mcp4131.MCP4131(s, cs)

    

    potval = m.set(0)

    direction = 1

    while True:

        time.sleep(.1)

        v = a.read_u16()

        print("[ %5.3f %5.3f %5.3f ]" % (0.0, 3.3*v/65536, 3.3))

        if direction == 1:

            potval = m.inc()

        else:

            potval = m.dec()

        if potval == 128:

            direction = -1

        if potval == 0:

            direction = 1

## Hardware overview

The MCP4131 is a simple single-wiper 7-bit digital potentiometer controlled by an SPI interface. It has no memory settings, so will forget its current setting when it loses power.

Spec/Datasheet: [mcp4131 | Microchip Technology](https://www.microchip.com/en-us/product/MCP4131)

## Methods

### Creation

    m = mcp4131.MCP4131(s, cs)

Takes two arguments:

* *s*, an SPI object

* *cs*, a Pin object for the SPI Chip Select line.

Note that on initialization, the potentiometer is set mid-way (64).

### set

Set the potentiometer to a value between 0 .. 128, inclusive. Returns the value of the potentiometer:

    potval = m.set(0)

    

### get

Gets the potentiometer value, a number between 0 .. 128 inclusive.

    potval = m.get()

### inc

Increments the value of the wiper. Will not go past 128. Returns a value between 0 .. 128, inclusive. 

    potval = m.inc()

### dec

Decrements the value of the wiper. Will not go past 0. Returns a value between 0 .. 128, inclusive. 

    potval = m.dec()

### value

Synonym for **get()**.

    potval = m.value()

    

### ratio

Simlar to  **get()**, but returns a floating point value from 0.0 .. 1.0.

    potratio = m.ratio()

## Note / Caveat

The MCP4131 uses a multiplexed data in/data out pin. Reading the wiper value is quite cumbersone, so I maintain the current potentiometer wiper value in a parallel variable. **get()** and others merely return the value of this variable. 

## Author

© 2021, Stewart Russell, scruss.com