Turn on/off individual LEDs on a 8x8 matrix driven by MAX7219

max7219-column2.py

#!/usr/bin/env python

import spi

### Initialize an SPI connection using BCM-mode pins 21, 20, and 16
max7219 = spi.SPI(clk=21, cs=20, mosi=16, miso=None, verbose=True)

### Zero out all registers
for cmd in range(16):
    packet = cmd << 8
    max7219.put(packet,12)

### Enable all columns via the scan limit register
max7219.put(int("101100000111",2),12)

### Disable shutdown mode
max7219.put(int("110000000001",2),12)

### Illuminate column 2 with a specific pattern
max7219.put(int("001000100111",2),12)

try:
    input("Press return to continue")
except:
    pass

max7219-individual-leds.py

#!/usr/bin/env python
"""
Change the state of a single LED in an 8x8 matrix.
"""

import spi

### Initialize an SPI connection using BCM-mode pins 21, 20, and 16
max7219 = spi.SPI(clk=21, cs=20, mosi=16, miso=None, verbose=True)

### Zero out all registers
for cmd in range(16):
    packet = cmd << 8
    max7219.put(packet,12)

### Set the scan limit register and disable shutdown mode
max7219.put(int("101100000111",2),12)
max7219.put(int("110000000001",2),12)

### We zeroed out all registers, so all LEDs are off (0)
led_state = [0]*64

def set_led(row, column, state):
    ### update our saved state
    led_state[column*8 + row] = state

    ### convert the new column into an SPI command
    register = (column+1) << 8
    value = 0
    for row in range(8):
        value <<= 1
        if led_state[column*8+row]:
            value |= 1

    max7219.put(register|value,12)

while True:
    row, col, state = input("Enter a row, col, state: ")
    set_led(row, col, state)

max7219-randomize-col5-8.py

#!/usr/bin/env python

import random
import time
import spi

### Initialize an SPI connection using BCM-mode pins 21, 20, and 16
max7219 = spi.SPI(clk=21, cs=20, mosi=16, miso=None, verbose=True)

### Zero out all registers
for cmd in range(16):
    packet = cmd << 8
    max7219.put(packet,12)

### Set the scan limit register and disable shutdown mode
max7219.put(int("101100000111",2),12)
max7219.put(int("110000000001",2),12)

### Illuminate column 2 with a specific pattern
max7219.put(int("001000100111",2),12)

### Fill columns 5-8 with a random pattern
while True:
    for column in (5, 6, 7, 8):
        register_addr = column << 8
        value = random.randint(0, 2**8-1)
        max7219.put(register_addr|value,12)
    time.sleep(0.5)