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The Dirty Dozen - Part Two - RPi Clone

This week I pulled out of the Dirty Dozen box a very cool RPi PICO clone.

To set myself a bit of a task I decided to program in MicroPython using Thonny, not the usual C via the Arduino IDE.

I had seen online some scuttlebutt about the ADC on these things being a little tricky, so I decided to test it out using an LDR which would then affect the integrated WS2812 LED to display light levels.

My Python skills were a little rusty, but after borrowing heavily from the internet, I was able to code the following.

import array, time
from machine import Pin
import rp2
 
# Configure the number of WS2812 LEDs, pins and brightness.
NUM_LEDS = 1
PIN_NUM = 23
brightness = 0.1

ldr = machine.ADC(27)
lightled = 0

BLACK = (0, 0, 0)
RED = (255, 0, 0)
YELLOW = (255, 150, 0)
GREEN = (0, 255, 0)
CYAN = (0, 255, 255)
BLUE = (0, 0, 255)
PURPLE = (180, 0, 255)
WHITE = (255, 255, 255)
COLORS = (WHITE, CYAN, YELLOW, GREEN, PURPLE, RED, BLUE, BLACK)

@rp2.asm_pio(sideset_init=rp2.PIO.OUT_LOW, out_shiftdir=rp2.PIO.SHIFT_LEFT, autopull=True, pull_thresh=24)
def ws2812():
    T1 = 2
    T2 = 5
    T3 = 3
    wrap_target()
    label("bitloop")
    out(x, 1)               .side(0)    [T3 - 1]
    jmp(not_x, "do_zero")   .side(1)    [T1 - 1]
    jmp("bitloop")          .side(1)    [T2 - 1]
    label("do_zero")
    nop()                   .side(0)    [T2 - 1]
    wrap()
 
# Create the StateMachine with the ws2812 program, outputting on Pin(16).
sm = rp2.StateMachine(0, ws2812, freq=8_000_000, sideset_base=Pin(PIN_NUM))
 
# Start the StateMachine, it will wait for data on its FIFO.
sm.active(1)
 
# Display a pattern on the LEDs via an array of LED RGB values.
ar = array.array("I", [0 for _ in range(NUM_LEDS)])
 
def pixels_show():
    dimmer_ar = array.array("I", [0 for _ in range(NUM_LEDS)])
    for i,c in enumerate(ar):
        r = int(((c >> 8) & 0xFF) * brightness)
        g = int(((c >> 16) & 0xFF) * brightness)
        b = int((c & 0xFF) * brightness)
        dimmer_ar[i] = (g<<16) + (r<<8) + b
    sm.put(dimmer_ar, 8)
    time.sleep_ms(10)
 
def pixels_set(i, color):
    ar[i] = (color[1]<<16) + (color[0]<<8) + color[2]
 
def pixels_fill(color):
    for i in range(len(ar)):
        pixels_set(i, color)
    
for color in COLORS:
    pixels_fill(color)
    pixels_show()
    time.sleep(1.5)
    
while True:
     lightled = ldr.read_u16()
     print(lightled)

     if lightled > 25000:
         pixels_fill(WHITE)
     elif lightled > 24000:
        pixels_fill(CYAN)
     elif lightled > 21000:
        pixels_fill(YELLOW)
     elif lightled > 18000:
        pixels_fill(GREEN)
     elif lightled > 15000:
        pixels_fill(PURPLE)
     elif lightled > 12000:
        pixels_fill(RED)
     elif lightled > 9000:
        pixels_fill(BLUE)
     elif lightled > 6000:
        pixels_fill(BLACK)

     pixels_show()
     time.sleep(0.2)

Loading up into the module was a breeze, and the second instalment of the Dirty Dozen was a success.