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.

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

### 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}