node-red-nodes/hardware/mcp3008/README.md

node-red-node-pi-mcp3008

A Node-RED node to read from the MCP3008 Analogue to Digital Converter, such as the Rasp.io analogzero, though it will work with breadboard versions also.

It will appear in the menu as A/D Converter.

Warning: Input voltages must not exceed 3.3V

Pre-requisites

You must ensure that SPI is enabled. For recent (2016) versions of Raspbian you can do this

• Run sudo raspi-config
• Select 9 - Advanced Options
• Select A5 - SPI
• Select yes to enable SPI
• Select OK to confirm
• Select the Finish button

Install

Run the following command in your Node-RED user directory - typically ~/.node-red

    npm install node-red-node-pi-mcp3008

Note: It will appear in the menu as A/D Converter.

### Usage

Reads from an MCP3008 Analogue to Digital (ADC) chip on the Pi SPI CE0 connection.

You can either set a channel in the edit dialogue, or you can set the msg.payload to select the channel dynamically. If so then the payload must be a value from 0 to 7.

Outputs a numeric msg.payload with a range of 0 to 1023, where 0 = 0V and 1023 = 3.3V (assuming you use the default 3.3V voltage reference).

Hint: use a range node to adjust the values to the range you want.

Also sets msg.topic to adc/{the pin number}