Introduction
In this video, we try to program WS2812B NeoPixel LED Stick Using Raspberry Pi Pico. The NeoPixel is controlled using a programmable I/O (PIO) system on a Pico microcontroller.
Video
Watch this video to know more about it.
Hardware Preparation
This is the list of items used in the video.
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| import array, time | |
| from machine import Pin | |
| import rp2 | |
| from rp2 import PIO, StateMachine, asm_pio | |
| # Configure the number of WS2812 LEDs. | |
| NUM_LEDS = 8 | |
| @asm_pio(sideset_init=PIO.OUT_LOW, out_shiftdir=PIO.SHIFT_LEFT, | |
| autopull=True, pull_thresh=24) | |
| def ws2812(): | |
| T1 = 2 | |
| T2 = 5 | |
| T3 = 3 | |
| 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] | |
| # Create the StateMachine with the ws2812 program, outputting on Pin(0). | |
| sm = StateMachine(0, ws2812, freq=8000000, sideset_base=Pin(0)) | |
| # 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. | |
| pixel_array = array.array("I", [0 for _ in range(NUM_LEDS)]) | |
| ############################################ | |
| # Functions for RGB Coloring | |
| ############################################ | |
| def updatePixel(brightness=1): # dimming colors and updating state machine (state_mach) | |
| dimmer_array = array.array("I", [0 for _ in range(NUM_LEDS)]) | |
| for ii,cc in enumerate(pixel_array): | |
| r = int(((cc >> 8) & 0xFF) * brightness) | |
| g = int(((cc >> 16) & 0xFF) * brightness) | |
| b = int((cc & 0xFF) * brightness) | |
| dimmer_array[ii] = (g<<16) + (r<<8) + b | |
| sm.put(dimmer_array, 8) # update the state machine with new colors | |
| def set_led_color(color): | |
| for ii in range(len(pixel_array)): | |
| pixel_array[ii] = (color[1]<<16) + (color[0]<<8) + color[2] | |
| #Color based on RGB (R,G,B) | |
| red = (255,0,0) | |
| green = (0,255,0) | |
| blue = (0,0,255) | |
| white = (255,255,255) | |
| set_led_color(red) | |
| updatePixel(1) | |
| time.sleep(1) | |
| set_led_color(green) | |
| updatePixel(1) | |
| time.sleep(1) | |
| set_led_color(blue) | |
| updatePixel(1) | |
| time.sleep(1) | |
| set_led_color(white) | |
| updatePixel(1) | |
| time.sleep(1) | |
References
- WS2812 LED Ring Light with Raspberry Pi Pico
- How to use WS2812B RGB LEDs with Raspberry Pi Pico
- Python enumerate(): Simplify Looping With Counters
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“Please be reminded, this tutorial is prepared for you to try and learn.
You are encouraged to improve the code for better application.“
