YOUR OFFICIAL RASPBERRY PI MAGAZINE

CHEERLIGHTS ORB
Tutorial
>STEP-03
Change the flow
Double-click the inject timestamp node. A dialog box
appears. Click the dropdown for Payload and choose
‘string’. Under ‘string’, type ‘red’; this will be the
message payload. In the ‘name’ box, rename the node
e.g. to ‘red’, then click OK. Deploy and then inject by
clicking the square on the left of the ‘red’ node. The
message payload (red) appears in the debug tab.
Add four more inject nodes and change the message
payloads to green, blue, white, and black. Connect
them all to the debug msg.payload node and deploy.
Inject each colour – the message payloads appear in
the debug tab.
>STEP-04
Add lights and orb
For both the LedBorg and separate LEDs, scroll down
the left-hand pane and drag a ledborg node onto the
flow. Connect the inject nodes to the ledborg. Deploy
and click some inject nodes; the LEDs or LedBorg will
light up with the corresponding colour.
Slice the bottom off the ping-pong ball and place over
the LedBorg to act as a diffuser. If using LEDs, cut a small
hole in the bottom of the ping-pong ball and push the
LEDs into it. Keep the LEDs as low as possible inside the
ball; use Blu-Tack to hold the ball if necessary.
>STEP-05
Connect to Twitter
Add a twitter input node from the social section – it
has a pimple on the right. Double-click and add Twitter
credentials; you’ll need to be logged into Twitter. In the
‘for’ box, add ‘cheerlights’. Add a function node; this
is used to keep the wires tidy, so double-click and call
it ‘spaghetti junction’. The message will pass through
and not be changed. This node can be used for adding
JavaScript code in future projects.
Delete all the wires, and rewire all the colour inputs
and twitter node to the input of the spaghetti
junction node. Connect a debug node to the output
of the spaghetti junction.
>STEP-06
Extract the colour
The LedBorg only accepts certain colours; extra words
such as ‘cheerlights’ means it won’t work. Connect
a yellow switch node to the output of spaghetti
junction. In its dropdown box, select ‘matches regex’;
next to that, type ‘red’ and tick the ‘ignore case’ button.
Click ‘+ rule’ and repeat for all the cheerlights colours;
they’re shown in the info tab for the ledborg node.
Connect a yellow change node to each of the outputs
of the switch node. Double-click each one, and set the
name and the payload to the required colour.
Connect all the outputs of the change nodes to
another spaghetti junction node, and then to an
ledborg node before deploying. You can add more
sheets on your Pi, but make sure there is only one
ledborg node, and pins 11,13, and 15 aren’t used
in other flows.
The code
The flow can be found at magpi.cc/1IH4rt1 or on
GitHub at magpi.cc/1IH4vc7. Copy the flow to the
clipboard, then import it into Node‐RED. Click on the
NodeRED menu (the hamburger icon), then Import,
Clipboard, paste the flow, and click OK.
WATCHDOG
TIMER
Add a ‘trigger’
node in parallel:
send nothing,
then wait 30
seconds, then
turn the string
payload black.
Tick ‘extend
delay if new
message arrives’.
DELAY
Add a delay
node to limit
the number
of messages
per minute
(limit rate to
four messages
per minute).
raspberrypi.org/magpi January 2016 59