1
0
mirror of https://github.com/node-red/node-red-nodes.git synced 2023-10-10 13:36:58 +02:00
node-red-nodes/hardware/sensehat/README.md

131 lines
3.9 KiB
Markdown

node-red-node-pi-sense-hat
==========================
A <a href="http://nodered.org" target="_new">Node-RED</a> node to interact with
a Raspberry Pi Sense HAT.
## Pre-requisites
The Sense HAT python drivers need to be installed manually:
```
sudo apt-get update
sudo apt-get install sense-hat
sudo pip-3.2 install pillow
```
See the <a href="http://pythonhosted.org/sense-hat/" target="_new">driver documentation</a>
for more information.
## Install
Run the following command in your Node-RED user directory (typically `~/.node-red`):
npm install node-red-node-pi-sense-hat
## Usage
### Input Node
This node sends readings from the various sensors on the Sense HAT, grouped into
three sets; motion events, environment events and joystick events.
#### Motion events
Motion events include readings from the accelerometer, gyroscope and magnetometer,
as well as the current compass heading. They are sent at a rate of approximately 10
per second. The `topic` is set to `motion` and the `payload` is an object with the
following values:
- `acceleration.x/y/z` : the acceleration intensity in Gs
- `gyroscope.x/y/z` : the rotational intensity in radians/s
- `orientation.roll/pitch/yaw` : the angle of the axis in degrees
- `compass` : the direction of North in degrees
#### Environment events
Environment events include readings from the temperature, humidity and pressure
sensors. They are sent at a rate of approximately 1 per second. The `topic`
is set to `environment` and the `payload` is an object
with the following values:
- `temperature` : degrees Celsius
- `humidity` : percentage of relative humidity
- `pressure` : Millibars
#### Joystick events
Joystick events are sent when the Sense HAT joystick is interacted with. The
`topic` is set to `joystick` and the `payload` is an object with the following values:
- `key` : one of `UP`, `DOWN`, `LEFT`, `RIGHT`, `ENTER`
- `state` : the state of the key:
- `0` : the key has been released
- `1` : the key has been pressed
- `2` : the key is being held down
### Output Node
This node sends commands to the 8x8 LED display on the Sense HAT.
Commands are sent to the node in `msg.payload`. Multiple commands can
be sent in a single message by separating them with newline (\n) characters.
#### Set the colour of individual pixels
Format: `<x>,<y>,<colour>`
`x` and `y` must either be a value from 0 to 7, a `*` to indicate the entire row
or column, or a range such as `3-6`.
`colour` must be one of:
- the well-known <a href="https://en.wikipedia.org/wiki/Web_colors" target="_new">HTML colour names</a> - eg `red` or `aquamarine`,
- the <a href="http://cheerlights.com/cheerlights-api/">CheerLights colour names</a>,
- a HEX colour value - eg `#aa9900`
- an RGB triple - `190,255,0`
- or simply `off`
To set the entire screen to red: `*,*,red`
To set the four corners of the display to red, green (#00ff00), yellow and blue (0,0,255):
`0,0,red,0,7,#00ff00,7,7,yellow,7,0,0,0,255`
To set a 3-pixel wide column to purple: `4-6,*,purple`
#### Rotate the screen
Format: `R<angle>`
`angle` must be 0, 90, 180 or 270.
#### Flip the screen
Format: `R<axis>`
`axis` must be either `H` or `V` to flip on the horizontal or vertical axis respectively.
#### Scroll a message
If `msg.payload` is not recognised as any of the above commands, it is treated
as a text message to be scrolled across the screen.
If the text is a single character, it will be displayed without scrolling. To
scroll a single character, append a blank space after it - `"A "`.</p>
The following message properties can be used to customise the appearance:
- `msg.color` - the colour of the text, default: `white`
- `msg.background` - the colour of the background, default: `off`
- `msg.speed` - the scroll speed. A value in the range 1 (slower) to 5 (faster), default: `3`
#### Set the screen brightness
Format: `D<level>`
`level` must be 0 (low) or 1 (high).