node-red-contrib-mcp3201

A node-red custom node wrapper for the nodejs mcp3201.js. by FredThx . This library uses the package pi-spi that enable the comunication with SPI devices in most commmon Linux SBCs. Raspberry Pi, C.H.I.P., BeagleBone, Orange Pi, or Intel Edison are supported by this package.

Installation

Under your node-red working directory.

npm install node-red-contrib-mcp3201

Node palette can be used as well to install the node.

After restarting node-red the "mcp3201" node should be available in "Input" category.

Prerequisites

Wiring :

MCP3201 : _ _ | U | Vref ---| |--- Vdd : 2.7V - 5V IN+ ---| |--- CLK IN- ---| |--- Dout 0V ---| |--- CS |___|

sur Rpi (SPI0):

Vref : 3.3V (ou 5V, ou ...) Vdd : 3.3V (ou 5V) CLK : SPI0_SCLK = GPIO11 Dout : SPI MISO = GPIO09 CS : - SPI0_CE0_N (GPIO08) => device : '/dev/spidev0.0' - SPI0_CE1_N_N (GPIO07) => device = '/dev/spidev0.1'

Caveat: Check your permissions to the /dev/spidev devices. The user running node-red need access to writting and reading. (on raspberry pi : sudo raspi-config)

Usage

Configuration & deployment

After installation place your mcp3201node in any of your flow and configure the following parameters:

1. Name: Select the name of your sensor for easy indentifiation.
2. Device: Select your spi device : '/dev/spidev0.0' (default) ou '/dev/spidev0.1' or ...
3. Ref_voltage: Select then referencial voltage (default is 3.3)
4. Topic: Select a topic

Reading Data

As in other node-red nodes the actual measurement of sensor data require that an input msg arrive to the node. The input called Trigger will start the reading of sensor data will send the data in the node's output.

The output will have the follwing format:

msg = {
  _id: <node-red msg_id>,
  topic: "__topic__",
  payload: value_in_volt
}

Notes

This node has been tested on Raspberry Pi 3

Change log.

• 0.0.1 Firts version