wl-mcp3008

A simple extension for reading Microchip MCP3008 A2D data via SPI in the Wolfram Language on the Raspberry Pi

by Joshua Schrier (2020) <jschrier [at] fordham [dot] edu>

Install

Pre-requisites:

(Tested on Raspbian 10 (buster) with Mathematica 12.0.1)

• wiring pi comes default in Raspbian (no installation necessary)
• Mathematica on the Raspberry Pi: the Makefile assumes version 12.0, but it is easy to change this.
• Be sure to enable SPI bus

From precompiled binary

A precompiled ARM-Linux binary for the Raspberry Pi (Raspian 10 on 3B+) is available in this repository. You can install it by running the following command in a terminal window:

curl https://github.com/jschrier/wl-mcp3008/blob/master/wl-mcp3008 --output ~/.Mathematica/Applications/wl-mcp3008

(This installs the package for the current user)

Compiling it yourself

Note: The mcc compiler script provided for Mathematica 12 on Raspberry Pi has some defects associated with the -m32 and -m64 compiler flags. The simple solution is to comment those lines in mcc file. Open the file:

/opt/Wolfram/WolframEngine/12.0/SystemFiles/Links/MathLink/DeveloperKit/Linux-ARM/CompilerAdditions/mcc

(or whatever your version of the WolframEngine is) and then comment out these lines:

else  # With gcc, target architecture is set by the -m32 and -m64 flags                                                
       if [ ${bitsize} = ${bit32} ] ; then                                                                             
           arch_flags="-m32"                                                                                           
       elif [ ${bitsize} = ${bit64} ] && [ "${archi}" = "x86_64" ] ; then                                              
               arch_flags="-m64"                                                                                       
       fi

Then just run:

make
make install

(default install path will put it into local user's .Mathematica/Applications/ directory, like above)

Usage

Minimum example (in Mathematica)

Install["wl-mcp3008"] (*loads the library*)

mcp3008[0] (* read from channel 0 *)

mcp3008[7] (*read from channel 7 *)

Returned values are integers; the MCP3008 returns 10 bit integers ranging from 0 to 1023.

Please note: This is hardwired to use the chip select channel 0 (CE0)