Currently using the Teensy 3.6 onboard SD card to create some light painting using 24bit BMP images stored on the sd card. Here is the result:
(code is over not he write-up page)
Category: Graphic Poi BMP from SD card
I have been through a number of different spec leds over the last few years, and this a warning, beware, not all led pixels are equal. Look at the specs and do your research as they are manufactured for different reasons, and so have different specs and limitations.
Some, like the WS2811, are manufactured in high density strips and are really easy to construct into batons, BUT… they have a timing issue and colour set function that makes them go blank for a tiny fraction of a second before each new colour is displayed, and so you get a slight pixelated effect.
Some, like the LPD 6803 are bright and fast at updating, BUT… are limited in colours and are not make in strips and therefore require lots of soldering. This leads to failures if not carefully made.
MAke sure you choose an led that has a driver chip clocked fast enough to handle your desired refresh rate.
Some are cheap, some are expensive, some have quality control issues, all have compromise. DO YOUR RESEARCH.
mortonkopf
I have had a few people ask me about the difference between pixel poi, graphic poi and visual poi. Well, they are all names for the same thing. However, the term pixel poi is a registered trade mark of the Feeding the Fish performance group, as “pixel-poi” with a hyphen I believe. Thats why other companies selling and using these types of poi use different names.
Here’s an image of a pixel poi, graphic poi, visual poi I built myself using a Teensy 3.0 micro controller with a strip of 60 ws2811 leds and a 4xAAA rechargeable batteries. Its not too difficult to do.
The code for this project is on the DIY Graphic / Pixel Poi page: https://orchardelica.com/wp/?page_id=228
The Graphic poi (pixel poi) project is now coming to a close. The final stage was to enable the leds to be updated from a series of BMP files held on an SD card. This way, it is possible to hold a large number of images on the device. The poi run off a Teensy 3 micro controller (see the other posts about this). I’m not happy with the result from these WS2811 leds, they give a happy appearance that I can’t do anything about, so I will not be using them further.
Here are some images and some code to get it all going.
the code is on the poi page. lots of this code comes from the good people over at the PJRC Forum where all things Teensy can be found. please go over and have a look and a chat if you need some help.
I have been looking at storing a larger volume of predefined images and displaying these on the Pixel / Graphic poi. Well, it finally seems to be working. Using the Teensy 3.0 with an SD card breakout board, the poi can grab the data from the SD card using the usual file format (Fat), with a 24bit BMP file. The files are only 60 pixels wide, as thats the number of leds on the poi, but are 150 pixels long so that we can get ore definition into the image displayed.
The current leds, however, are not good at POV. These are the ws2811 ones, and they just don’t do the business fast enough.
Next step is to hook the system up to some different leds and see how it performs.
Code for the Teensy 3.0 to follow after some tidying up.
mortonkopf