{"id":2567,"date":"2018-12-19T00:00:35","date_gmt":"2018-12-18T23:00:35","guid":{"rendered":"https:\/\/iot.fkainka.de\/?p=2567"},"modified":"2018-11-21T16:38:09","modified_gmt":"2018-11-21T15:38:09","slug":"day19-2018","status":"publish","type":"post","link":"https:\/\/iot.fkainka.de\/en\/day19-2018","title":{"rendered":"Day 19: CheerLights"},"content":{"rendered":"

Today we have a very special LED waiting behind the door. It is an RGB LED with integrated controller (type PL9823, equivalent to WS2812) and with it you can now connect several LEDs in series and control them individually by means of a protocol. Today we will start by controlling one LED only. Here, an experiment that is almost customary in my Advent calendars fits in handy: the CheerLights project by Hans Schaaler. For all those who do not yet know the project: these are globally linked colourful lights which can be controlled simultaneously via Twitter commands. And here Node-RED fits in very well. The experiment today requires the following setup besides the program of today.<\/p>\n

\"So<\/a>

A proper connected PL9823 (long legs right)<\/p><\/div>\n

The LED is controlled by a set of commands. It is activated by the term Pixel<\/strong>. But first and foremost, we will learn today how we control all LEDs of the same colour as we are dealing with only one LED. In one of the coming experiments we will explain all the commands that can be used for\u00a0assigning individual colours to the LEDs.<\/p>\n\n\n\n\n\n\n\n\n\n
Command in topic<\/strong><\/td>\nSettings<\/strong><\/td>\n<\/tr>\n
{“cmd”:”set_pixel_hex”,”value”:”#FFFFFF”}<\/td>\nSets all LEDs to the HEX colour value.<\/td>\n<\/tr>\n
{“cmd”:”set_pixel_rgb”,”value”:”rgb(255,255,255)”}<\/td>\nSets all LEDs to the RGB colour value.<\/td>\n<\/tr>\n
{“cmd”:”set_pixel_hsv”,”value”:”hsv(120, 100%,100%)”}<\/td>\nSets all LEDs to the HSV colour value.<\/td>\n<\/tr>\n
{“cmd”:”get_pixel_hex”}<\/td>\nDisplays current colour in the appropriate format, returns automatically when a colour is set.<\/td>\n<\/tr>\n
{“cmd”:”get_pixel_rgb”}<\/td>\n<\/tr>\n
{“cmd”:”get_pixel_hsv”}<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The CheerLights project has a website (https:\/\/cheerlights.com\/<\/a><\/strong>) where you can get some information about the project. Moreover, one of the subpages, Cheerlights API<\/strong>, has a bunch of options of how to obtain the actual colour value. We are using here the interface http:\/\/api.thingspeak.com\/channels\/1417\/field\/2\/last.json <\/a><\/strong>which offers the current value as JSON value and in HEX format.<\/p>\n

\"Der<\/a>

Today’s Flow<\/p><\/div>\n