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DisplayMAX7219 Element

The DisplayMAX7219 Element implements a larger display by using LED 8x8 led displays matrixes based on MAX7219 controller chips.

This display implementation supports LED matrix setup with 1 line of 8x8 modules using the GFX 8-pixel font.

The DisplayMAX7219 Element needs to be configured for using the standard SPI interface and specifying the select GPIO pin.

The parent class DisplayElement implements the configuration that is passed to the adapter implementation to initialize the hardware and canvas.

The DisplayAdapterMAX7219 uses the canvas class from the Adafruit_GFX library to create an in-memory picture that can be shifted to the display when drawing of the output element has finished.

To show some output on the display use the DisplayText Element and the DisplayDot Element

LED matrix based on MAX7219

Connectivity

The MAX7219 based displays uses a SPI based data interface sending data out only. On ESP8266 the standard SPI interface is used. On ESP32 the VSPI interface is used.

The display must use it’s own chip select (CS) line.

MAX7219 ESP8266 ESP32 max7219
VCC VCC VCC +5V, VCC from USB
GND GND GND Common Ground
DIN GPIO13(D7) GPIO23 SPI-MOSI, Data to Matrix
CS GPIO0(D3) GPIO05 CS, Select signal
CLK GPIO14(D5) GPIO18 SPI-CLK, Clock

See also Using the SPI bus

Element Configuration

The following properties are available for configuration of the element:

Property Description
spiCS Specifies the spi component select pin of the display.
height The height of the display. 32 or 64

Configuration Example

The configuration of a display is given by the provided hardware and should be configured in the env.json file.

This example shows how to configure this element:

{
  "DisplayMAX7219": {
    "0": {
      "width": 32,
      "height": 8,
      "brightness": 10,
      "spiCS": "D3"
    }
  }
}

See also

Tags

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