go-max31855

This is a simple package for interfacing with the MAX31855 thermocouple amplifier over SPI.

Compatibility

Tested on a Raspberry Pi 3B using an Adafruit MAX31855 sensor. It should be fine for other variants of Linux / RPi devices, but you might need to adjust the build settings (e.g. GOARCH, GOARM)

Usage

Use this library in your project: go get github.com/teebr/go-max31855

There's not much to it: a MAX31855 type with the file descriptor, internal temperature, thermocouple temperature and the timestamp when the measurements were read. There are three methods: Open, Read and Close. Open requires the name of the SPI device (e.g. /dev/spidev0.0). Read() then reads from the amplifier, checks for errors, and then populates the Internal, Thermocouple and Timestamp fields.

Examples

There are two examples:

• basic which prints the temperatures every 100ms (about as fast as the sensor updates its readings),
• streaming, which creates a small webserver with a graph for the two temperatures on port 8080 of your device. This opens a websocket from the server to the browser to stream data, and uses Plotly to view the data in real-time. There are a couple of basic widgets to control the data rate, time window and to pause streaming. Gorilla Websockets are used for this example, so go get github.com/gorilla/websocket before building it.

Build

I find it simpler to develop on a regular computer then cross-compile, rather than installing Go on the Raspberry Pi. To do this:

GOOS=linux GOARCH=arm GOARM=7 go build src/github.com/teebr/go-max31855/examples/[NAME]/[NAME].go then scp the files to your Pi (for streaming make sure to copy the html file as well as the executable)