[0:01] A random mess of LEDs
[0:04] No structure
[0:06] No order
[0:08] Complete chaos
[0:28] Order has emerged.
[0:30] We have a discernible geometric pattern on our leds.
[0:36] How does this work?
[0:38] Let’s have a look under the hood.
[0:42] We’re using an ESB 32 camera board
[0:46] With some simple image processing
[0:49] and a string of WS2811 addressable RGB LEDs.
[0:56] Wiring up the addressable LEDs is pretty straightforward
[1:00] they just require a power supply and data connection.
[1:05] Data is sent to the first LED on its data pin
[1:09] it keeps the bits that are meant for it and sends the remaining data on to the next LED.
[1:16] This happens down the chain of LEDs and until of a none left.
[1:24] To program the ESP 32 we need a USB to UART board.
[1:29] Once we’ve downloaded the initial sketch
[1:32] we can switch over to over-the-air updates which makes things quite a bit more convenient.
[1:38] To talk to the addressable LEDs we also need a level shifter
[1:43] the ESP board can only output 3.3 volts and the addressable LEDs
[1:48] require 5 volts to work reliably.
[1:53] There are many ways to do level shifting
[1:55] Adafruit have several boards that you can use and I’ve got a mosfet driver
[2:00] left over from another project that I’m going to use.
[2:04] Let’s quickly run through the circuit for driving the LEDs.
[2:08] I’ve decided to have two separate power supplies
[2:13] One for the LEDs and one for the ESP 32.
[2:17] The LEDs require a fair amount of power
[2:22] and the ESP cam is quite sensitive to voltage drops and seems to brown out very easily.
[2:29] I’ve also added a couple of large capacitors across each power supply.
[2:35] We need to make sure there is a common ground between both power supplies
[2:40] so we connect the two ground pins.
[2:44] For the level shifting I’m using my FET driver and I’m also adding a small
[2:49] decoupling capacitor to this chip.
[2:52] Finally we can add the cables for the ESP32 and for the LEDs.
[2:59] Connecting the power ground and data lines
[3:03] That’s our circuit complete let’s talk about the software.
[3:08] To make the whole thing work we need to know where each LED is.
[3:13] To do this we apply some simple image processing.
[3:17] For each LED in the string we capture a frame with all the LEDs off.
[3:23] We then light one individual LED and capture another frame.
[3:29] These two frames are compared
[3:33] and the location of the LED is determined by finding the part of the
[3:37] image with the largest difference.
[3:40] Repeating this lets us work out the
[3:42] approximate positions for each LED in the string.
[3:47] To display an image on the LEDs we create a frame buffer
[3:52] and draw out required image into that frame buffer.
[3:56] we then run through each LED and take the color that the LED should be
[4:01] given its position on the image.
[4:05] To provide user interface to the board
[4:07] I’ve built a very simple web interface that is served from the ESP 32 cam device.
[4:13] We can capture a frame from the sensor
[4:17] We can tell the system to recalibrate the LEDs
[4:23] and we can also pause and resume the animation sequence.
[4:29] All the code for the project is on GitHub.
[4:33] Let me know if you have any comments or suggestions.
[4:36] and please do hit the subscribe button
[4:39] It’s the only way I have of knowing if you like these videos and want more.
[4:44] Thanks for watching and I’ll see you in the next video!