Raspberry Pi driver for MAX7219 with 7-segment modules
- Utilizes hardware SPI (spidev library is required)
- Supports cascading MAX7219 devices
- Number of digits per MAX7219 device can be specified
max7219.py uses an internal buffer (array) that is a direct representation of the display when flushed. So buffer[0] is the leftmost digit in the display and buffer[digits] is the rightmost. Also, digit0 is the leftmost and digit7 is rightmost for each MAX7219 device. Cascaded devices add additional digits to the right.
If you have a pre-wired 7-segment display module that has the rightmost digit as digit0, then set the reverse parameter to True when you initialize the driver so that the digits will display in the correct order.
If less than 8 digits are connected to the MAX7219, set the scan_digits parameter when initializing so that the code properly handles text value inputs and cascading. The digits initialization value represents the total number of digits across all cascaded devices.
seven_segment_ascii.py maps ascii characters to their segment representations. get_char() uses a DP-G-F-E-D-C-B-A bit order and get_char2() uses a DP-A-B-C-D-E-F-G bit order (which is what the MAX7219 specifies).
To install the library directly from github, you can enter the following from a command prompt on your Raspberry Pi:
pip3 install git+https://github.com/JennaSys/rpi-max7219.gitimport max7219
display = max7219.SevenSegment(digits=16, scan_digits=8, reverse=True)
display.text("ABCDEF")
display.number(3.14159)
display.message("Hello World")
display.clear()| Raspberry Pi | MAX7219 LED Driver |
|---|---|
| 5V | VCC |
| GND | GND |
| SPI0_MOSI | DIN |
| SPI0_CE0 | CS |
| SPI0_SCLK | CLK |
NOTE: A level shifter (i.e. 2N7000) may be required on the data lines going to the MAX7219 to change the 3.3V logic to 5V
This library is based on:
- rm-hull's max7219.py (pre-2017 version) for the Raspberry Pi (PyPI Project)
- dmadison's Segmented LED Display - ASCII Library
Licensed under the MIT License.