ESP HTTP NeoMatrix Text

Control a Neopixel Matrix over HTTP.

This is basically an adapted version of the Text Neopixel Matrix controllable via MQTT I am using for myself. But having a dedicated MQTT Server running might not be suitable for everyone.

HTTP Routes

You can GET and POST each of these routes to view the current value or set a new one.

• /hue

  Hue from 0° to 360°

  

• /sat

  Saturation from 0 to 100

• /bri

  Brightness from 0 to 252

  This value is normalized so 1 is the lowest brightness possible for green (hue 120). Also, as the idea of this matrix is to display text the high brightness values are not as interesting (personally I only use 0-100)

• /on

  Can be either 1 or 0

  Turns off the matrix. Keep in mind that the matrix is still consuming power due to the resistors. See power consumption

  Pin 5 (D1) is set to follow this value. This way you can for example make use of relays to completely power down the matrix.

  Or simply unplug the matrix when you do not use it, and it will not consume any power that way.

• /text

  Can be a string of your wishes without line breaks. If the text is longer than the matrix is wide the text is scrolled through.

Install on the ESP

Warning: Make sure to either disconnect the matrix or power it from an external source while connecting via USB! Otherwise, your ESP might smell badly and is useless afterwards.

Prebuilt

I tested this with an ESP8266 / NodeMCU.

• Get the esptool (It might also be in your package manager)
• Download the firmware.bin from the Releases
• Connect the ESP8266 / NodeMCU via USB to your computer. Make sure to either disconnect the matrix or power it from an external source while connecting via USB!
• Execute esptool.py write_flash 0x0 ./firmware.bin

Compile yourself

• Install PlatformIO
• run pio run --target upload or use the IDE button to upload

Wiring

Power the LED Matrix via its own Power Connections (+-) with 5V.

Connect the Matrix Input Connection to the ESP 8266

• 5V (probably red) to Vin
• GND (probably white) to GND
• Data (probably green) to GPIO 13 / D7

This way the ESP is powered via the Matrix and can be programmed while connected to the matrix.

Warning: If you power the matrix indirectly through the ESP make sure to keep the brightness low. High brightness results in higher power consumption which the ESP can not handle.

Yes, I'm sure. I accidentally tried. Can't recommend the smell.

Power consumption

The simplest way to power the matrix with 5V is via a USB power supply like the ones from mobile devices/phones. As this matrix is meant for text most pixels will not be used and also the brightness does not need to be high. While the matrix might consume > 1A with all pixels lit this is not the case for text. Using a 1A power supply is definitely enough.

Some measurements

• ~1.4W while off
• ~1.5W with the default brightness / text,
• ~7.9W with white max brightness text "12345" (=5V 1.6A)
• ~9W with max brightness all led rainbow (not from this program)

Connect it to your Wi-Fi

When the ESP has no connection to a Wi-Fi it creates a hotspot. The default name is ESP-Matrix with the default password ich will text (German for 'I want text'). When programming the ESP you can change these values in the first few lines in the program code.

When connecting to the Hotspot an interface will allow you to specify the name and password of your local Wi-Fi.

Once you did, you can close the configuration website and the ESP will connect your Wi-Fi. It is then available with the hostname ESP-Matrix.

For more information about this process see the documentation of the WiFiManager Library

As a little indicator the onboard LED will show the current connection status. After powering on the ESP the LED will also turn on. It will turn off when the ESP has successfully connected to Wi-Fi and is ready to receive HTTP Requests.

Sometimes the ESP does not connect to your Wi-Fi (onboard LED stays on) and opens its configuration portal. Simply reset the ESP (RST button) to retry.