3.6 KiB
node-red-node-pi-sense-hat
A Node-RED 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 driver documentation 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 in the range 0-7, or * to indicate the entire row or column.
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
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.
The following message properties can be used to customise the appearance:
- `msg.colour` - 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`