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

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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
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This node sends readings from the various sensors on the Sense HAT, grouped into
three sets; motion events, environment events and joystick events.
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#### 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
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- `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
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#### 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:
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- `temperature` : degrees Celsius
- `humidity` : percentage of relative humidity
- `pressure` : Millibars
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#### 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:
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- `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
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### 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
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Format: `<x>,<y>,<colour>`
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`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:
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- 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`
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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
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Format: `R<angle>`
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`angle` must be 0, 90, 180 or 270.
#### Flip the screen
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Format: `R<axis>`
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`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>
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The following message properties can be used to customise the appearance:
- `msg.color` - the colour of the text, default: `white`
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- `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`
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#### Set the screen brightness
Format: `D<level>`
`level` must be 0 (low) or 1 (high).