Installation

Note

The library has been tested against Python 2.7 and 3.4+.

For a Python 3 installation, substitute the following in the instructions below.

  • pippip3,
  • pythonpython3,
  • python-devpython3-dev,
  • python-pippython3-pip.

Pre-requisites

MAX7219 Devices

By default, the SPI kernel driver is NOT enabled on a Raspberry Pi Raspbian image. You can confirm whether it is enabled using the shell command below:

$ lsmod | grep -i spi
spi_bcm2835             7424  0

Depending on the hardware/kernel version, this may report spi_bcm2807 rather than spi_bcm2835 - either should be adequate.

And to verify that the devices are successfully installed in /dev:

$ ls -l /dev/spi*
crw------- 1 root root 153, 0 Jan  1  1970 /dev/spidev0.0
crw------- 1 root root 153, 1 Jan  1  1970 /dev/spidev0.1

If you have no /dev/spi files and nothing is showing using lsmod then this implies the kernel SPI driver is not loaded. Enable the SPI as follows (steps taken from https://learn.sparkfun.com/tutorials/raspberry-pi-spi-and-i2c-tutorial#spi-on-pi):

  1. Run sudo raspi-config
  2. Use the down arrow to select 5 Interfacing Options
  3. Arrow down to P4 SPI
  4. Select yes when it asks you to enable SPI
  5. Also select yes when it asks about automatically loading the kernel module
  6. Use the right arrow to select the <Finish> button
  7. Reboot.
_images/raspi-spi.png

After rebooting re-check that the lsmod | grep -i spi command shows whether SPI driver is loaded before proceeding. If you are stil experiencing problems, refer to the official Raspberry Pi SPI troubleshooting guide for further details, or ask a new question - but please remember to add as much detail as possible.

GPIO pin-outs

MAX7219 Devices (SPI)

The breakout board has two headers to allow daisy-chaining:

Board Pin Name Remarks RPi Pin RPi Function
1 VCC +5V Power 2 5V0
2 GND Ground 6 GND
3 DIN Data In 19 GPIO 10 (MOSI)
4 CS Chip Select 24 GPIO 8 (SPI CE0)
5 CLK Clock 23 GPIO 11 (SPI CLK)

See also

Also see the section for cascading/daisy-chaining, power supply and level-shifting.

WS2812 NeoPixels (DMA)

Typically, WS2812 NeoPixels reqire VCC, VSS (GND) and DI pins connecting to the Raspberry Pi, where the DI pin is usually connected to a PWM control pin such as GPIO 18.

Board Pin Name Remarks RPi Pin RPi Function
1 DO Data Out
2 DI Data In 12 GPIO 18 (PWM0)
3 VCC +5V Power 2 5V0
4 NC Not connected
5 VDD Not connected
6 VSS Ground 6 GND

The DO pin should be connected to the DI pin on the next (daisy-chained) neopixel, while the VCC and VSS are supplied in-parallel to all LED’s. WS2812b devices now are becoming more prevalent, and only have 4 pins.

NeoSegments

@msurguy’s NeoSegments should be connected as follows:

Board Pin Name Remarks RPi Pin RPi Function
1 GND Ground 6 GND
2 DI Data In 12 GPIO 18 (PWM0)
3 VCC +5V Power 2 5V0

Installing from PyPi

Install the dependencies for library first with:

$ sudo usermod -a -G spi,gpio pi
$ sudo apt install build-essential python-dev python-pip libfreetype6-dev libjpeg-dev libopenjp2-7 libtiff5

Warning

The default pip and setuptools bundled with apt on Raspbian are really old, and can cause components to not be installed properly. Make sure they are up to date by upgrading them first:

$ sudo -H pip install --upgrade --ignore-installed pip setuptools

Proceed to install latest version of the luma.led_matrix library directly from PyPI:

$ sudo -H pip install --upgrade luma.led_matrix

Examples

Ensure you have followed the installation instructions above. Clone the repo from github, and run the example code as follows:

$ python examples/matrix_demo.py

The matrix demo accepts optional flags to configure the number of cascaded devices and correct the block orientation phase shift when using 4x8x8 matrices:

$ python examples/matrix_demo.py -h
usage: matrix_demo.py [-h] [--cascaded CASCADED]
                      [--block-orientation {0,90,-90}] [--rotate {0,1,2,3}]
                      [--reverse-order REVERSE_ORDER]

matrix_demo arguments

optional arguments:
  -h, --help            show this help message and exit
  --cascaded CASCADED, -n CASCADED
                        Number of cascaded MAX7219 LED matrices (default: 1)
  --block-orientation {0,90,-90}
                        Corrects block orientation when wired vertically
                        (default: 0)
  --rotate {0,1,2,3}    Rotate display 0=0_, 1=90_, 2=180_, 3=270_
                        (default: 0)
  --reverse-order REVERSE_ORDER
                        Set to true if blocks are in reverse order (default:
                        False)

Similarly, there is a basic demo of the capabilities of the luma.led_matrix.virtual.sevensegment wrapper:

$ python examples/sevensegment_demo.py

and for the luma.led_matrix.device.neopixel device:

$ sudo python examples/neopixel_demo.py

Further examples are available in the luma.examples. git repository. Follow the instructions in the README for more details.

A small example application using ZeroSeg to display TOTP secrets can be found in https://github.com/rm-hull/zaup.