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318a75c41b
* Update the 'Node Help' Expanded the explanation for using multiple commands. Provided examples for Rotate, Flip and Display. Added examples for rotate, flip and screen brightness and added line to multiple messages explaination. changed the Flip format from 'R' to 'F'
139 lines
4.1 KiB
Markdown
139 lines
4.1 KiB
Markdown
node-red-node-pi-sense-hat
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==========================
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A <a href="http://nodered.org" target="_new">Node-RED</a> node to interact with
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a Raspberry Pi Sense HAT.
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## Pre-requisites
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The Sense HAT python drivers need to be installed manually:
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```
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sudo apt-get update
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sudo apt-get install sense-hat
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sudo pip-3.2 install pillow
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```
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See the <a href="http://pythonhosted.org/sense-hat/" target="_new">driver documentation</a>
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for more information.
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## Install
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Run the following command in your Node-RED user directory (typically `~/.node-red`):
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npm install node-red-node-pi-sense-hat
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## Usage
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### Input Node
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This node sends readings from the various sensors on the Sense HAT, grouped into
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three sets; motion events, environment events and joystick events.
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#### Motion events
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Motion events include readings from the accelerometer, gyroscope and magnetometer,
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as well as the current compass heading. They are sent at a rate of approximately 10
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per second. The `topic` is set to `motion` and the `payload` is an object with the
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following values:
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- `acceleration.x/y/z` : the acceleration intensity in Gs
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- `gyroscope.x/y/z` : the rotational intensity in radians/s
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- `orientation.roll/pitch/yaw` : the angle of the axis in degrees
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- `compass` : the direction of North in degrees
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#### Environment events
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Environment events include readings from the temperature, humidity and pressure
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sensors. They are sent at a rate of approximately 1 per second. The `topic`
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is set to `environment` and the `payload` is an object
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with the following values:
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- `temperature` : degrees Celsius
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- `humidity` : percentage of relative humidity
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- `pressure` : Millibars
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#### Joystick events
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Joystick events are sent when the Sense HAT joystick is interacted with. The
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`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`
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- `state` : the state of the key:
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- `0` : the key has been released
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- `1` : the key has been pressed
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- `2` : the key is being held down
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### Output Node
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This node sends commands to the 8x8 LED display on the Sense HAT.
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Commands are sent to the node in `msg.payload`. Multiple commands can
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be sent in a single message by separating them with newline (\n) characters.
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You must use a function node or a change node (jsonata expression) when
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using the newline (\n) character to create a payload containing multiple commands.
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#### 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 from 0 to 7, a `*` to indicate the entire row
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or column, or a range such as `3-6`.
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`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`,
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- the <a href="http://cheerlights.com/cheerlights-api/">CheerLights colour names</a>,
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- a HEX colour value - eg `#aa9900`
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- an RGB triple - `190,255,0`
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- or simply `off`
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To set the entire screen to red: `*,*,red`
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To set the four corners of the display to red, green (#00ff00), yellow and blue (0,0,255):
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`0,0,red,0,7,#00ff00,7,7,yellow,7,0,0,0,255`
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To set a 3-pixel wide column to purple: `4-6,*,purple`
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#### Rotate the screen
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Format: `R<angle>`
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`angle` must be 0, 90, 180 or 270.
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Example: `R180`
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#### Flip the screen
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Format: `F<axis>`
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`axis` must be either `H` or `V` to flip on the horizontal or vertical axis respectively.
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Example: `FV`
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#### Scroll a message
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If `msg.payload` is not recognised as any of the above commands, it is treated
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as a text message to be scrolled across the screen.
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If the text is a single character, it will be displayed without scrolling. To
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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:
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- `msg.color` - the colour of the text, default: `white`
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- `msg.background` - the colour of the background, default: `off`
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- `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
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Format: `D<level>`
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`level` must be 0 (low) or 1 (high).
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Example: `D1`
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