IoT LED Matrix

Subsequent to the work done of previous instructables (IoT Development With Mobile Directly), This instructables show how to develop an IoT LED Matrix with your mobile and a MINTIA sweet box.

Step 1: Preparation

• an empty MINTIA sweet box
• 1 meter 144 units SK6812 3535 LED strip (only use 60 units)
• ESP-12E
• micro USB female connect board
• 3.3 V regulate board
• Lipo charge board
• Lipo battery 343450
• some coated copper wire
• a small piece of PET plastic plate
• a power switch
• a USB to TTL cable for initial program the ESP board

Step 2: Flash NodeMCU Firmware and Nodemcu-httpserver

Follow my previous instructables to flash NodeMCU firmware and upload nodemcu-httpserver.

Step 3: Programming

After the previous steps, you can program the ESP board any time with your mobile or the notebook through WiFi connection.

But it is better to test it in an earliest stage:

1. browse the ESP board with the IP recorded in previous step, you can see the index page.
2. click the Editor link
3. copy and paste the led-matrix.html.txt file content to the editor page textarea
4. fill in save file as "led-matrix.html"
5. press save button
6. wait few ten seconds for save complete
7. copy and paste the led-matrix.lua code to the editor page textarea
8. fill in save file as "led-matrix.lua"
9. press save button
10. wait few ten seconds for save and compile complete
11. test browse to http://[your ESP IP]/led-matrix.html

Step 4: Patch the MINTIA Sweet Box

1. remove the sticker of the MINTIA sweet box
2. split the box
3. cut and remove all the plastic parts in the middle

Step 5: Check Component Thickness

The MINTIA sweet box is around 7mm thick, the internal part is around 5mm thick. Deduct the LED strip thickness, only remain 3.3 mm for all other components.

The micro USB female board is a little thicker than that, so require some patch.

Step 6: Design Layout

Everything just fit in the MINTIA sweet box.

Step 7: LED Support Plate

Cut a PET plastic plate a little bit smaller than the MINITA internal size.

Step 8: Assembly LED Strip

Cut 6 LED strips with 10 SK6812 units each.

Stick all LED strips to the PET plastic plate to make it become a LED matrix.

Step 9: Soldering

LED Strip Matrix

• connect LED signal circuit in zigzag order from top left to bottom right
• connect LED strip Vcc altogether -> 3.3 V regulate board Vout
• connect LED strip GND altogether -> 3.3 V regulate board GND

ESP-12E Board

• RESET PIN (PIN 1), EN PIN (PIN 3), Vcc PIN (PIN 8) -> 3.3 V regulate board Vout
• GND PIN (PIN 15), GPIO15 (PIN 16) -> 3.3 V regulate board GND
• GPIO02 PIN -> LED strip DIN
• I have abused the micro USB connector D+ and D- PIN to Tx and Rx in case I need to debug

Lipo Charge Board

• Battery +ve -> Lipo battery +ve -> power switch -> 3.3 V regulate board Vin
• Battery -ve -> Lipo battery -ve -> 3.3 V regulate board GND
• Vin -> micro USB board 5V
• GND -> micro USB board GND

Step 10: Happy Coding!

You can now:

• browse to http://[your ESP IP]/led-matrix.html for playing with your LED Matrix
• browse to http://[your ESP IP]/editor.html for editing and enhance your own code

led-matrix.lua is only a simple example, ESP with LED strip can make much more:

• utilize ESP board RTC and WiFi SNTP to make a slim clock
• led-text.lua show how can use html5 canvas to draw text on LED matrix
• and more