Python 3.x module for use with MCP4131 digital potentiometer.
This requires the py-spidev and python-dev modules for the SPI connection. I used an MCP4131 10kOhm digital pot connected to a Raspberry Pi 3 for development of this module.
Connections to the MCP4131 from the Pi are as follows
- Pi MOSI to 560 ohm resistor to MCP SDI/SDO
- Pi MISO to MCP SDI/SDO
- Pi SCLK to MCP SCK
- Pi CE1 to MCP CS
- Pi 3.3V to MCP Vdd
- Pi Gnd to MCP Gnd/Vss
For testing I used a Fluke7 3 Series II multimeter measuring ohms placed across the MCP P0B and MCP P0W terminals
Current functions include:
- set_wiper_value(wiperValue = 0x40, wiper = 0):=
- read_wiper_value(wiper = 0)
- increment_wiper(increment = 1, wiper = 0)
- decrement_wiper(decrement = 1, wiper = 0)
- set_wiper_controls(pA = 1, pW = 1, pB= 1, shutdown = 1, wiper = 0)
- read_wiper_controls()
For information on how the chip works check out the datasheet
Note: For the increment and decrement commands I did not use the 8 bit increment/decrement commands found in the data sheet. They never worked for me, on the Pi or on an Arduino UNO. I used a 2 step version instead where I read the current wiper value first and then increment/decrement that by the specified amount and write that value back to the wiper value register.