node-red-node-pi-mcp3008 ======================== A <a href="http://nodered.org" target="_new">Node-RED</a> node to read from the MCP3xxx Series of Analogue to Digital Converters, such as the <a href="http://rasp.io/analogzero" target="_new">Rasp.io analogzero</a>, 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 `5 - Interfacing Options` - Select `P4 - 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 MCP3xxx Analogue to Digital (ADC) chip on the Pi SPI 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. You can also select device id 0 or 1 (CE0 or CE1) depending on how you have wired up your device. Defaults to CE0. And you can also select the SPI bus number 0 or 1 depending on how you have wired up your device. Defaults to 0 for spidev0. 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}`