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WS2812B RGB三色灯的控制
; ; Copyright (c) 2020 Raspberry Pi (Trading) Ltd. ; ; SPDX-License-Identifier: BSD-3-Clause ; .program ws2812 .side_set 1 .define public T1 2 .define public T2 5 .define public T3 3 .lang_opt python sideset_init = pico.PIO.OUT_HIGH .lang_opt python out_init = pico.PIO.OUT_HIGH .lang_opt python out_shiftdir = 1 .wrap_target bitloop: out x, 1 side 0 [T3 - 1] ; Side-set still takes place when instruction stalls jmp !x do_zero side 1 [T1 - 1] ; Branch on the bit we shifted out. Positive pulse do_one: jmp bitloop side 1 [T2 - 1] ; Continue driving high, for a long pulse do_zero: nop side 0 [T2 - 1] ; Or drive low, for a short pulse .wrap % c-sdk { #include "hardware/clocks.h" static inline void ws2812_program_init(PIO pio, uint sm, uint offset, uint pin, float freq, bool rgbw) { pio_gpio_init(pio, pin); pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true); pio_sm_config c = ws2812_program_get_default_config(offset); sm_config_set_sideset_pins(&c, pin); sm_config_set_out_shift(&c, false, true, rgbw ? 32 : 24); sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX); int cycles_per_bit = ws2812_T1 + ws2812_T2 + ws2812_T3; float div = clock_get_hz(clk_sys) / (freq * cycles_per_bit); sm_config_set_clkdiv(&c, div); pio_sm_init(pio, sm, offset, &c); pio_sm_set_enabled(pio, sm, true); } %} .program ws2812_parallel .define public T1 2 .define public T2 5 .define public T3 3 .wrap_target out x, 32 mov pins, !null [T1-1] mov pins, x [T2-1] mov pins, null [T3-2] .wrap % c-sdk { #include "hardware/clocks.h" static inline void ws2812_parallel_program_init(PIO pio, uint sm, uint offset, uint pin_base, uint pin_count, float freq) { for(uint i=pin_base; i<pin_base+pin_count; i++) { pio_gpio_init(pio, i); } pio_sm_set_consecutive_pindirs(pio, sm, pin_base, pin_count, true); pio_sm_config c = ws2812_parallel_program_get_default_config(offset); sm_config_set_out_shift(&c, true, true, 32); sm_config_set_out_pins(&c, pin_base, pin_count); sm_config_set_set_pins(&c, pin_base, pin_count); sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX); int cycles_per_bit = ws2812_parallel_T1 + ws2812_parallel_T2 + ws2812_parallel_T3; float div = clock_get_hz(clk_sys) / (freq * cycles_per_bit); sm_config_set_clkdiv(&c, div); pio_sm_init(pio, sm, offset, &c); pio_sm_set_enabled(pio, sm, true); } %}
WS2812B教程内容
1. 连线图
The wiring diagram between the Raspberry Pi Pico and a 16-pixel RGB LED ring light is shown below:
Wiring Diagram
The pinout wiring is also given in the table below:
Power Supply Pico Ring Light + N/A 5V N/A GPIO13 DI - GND GND Most of the GPIO pins can be used to control the WS2812 LED array, thus, the specification of GPIO13 for controlling the light is arbitrary. Be sure to change the pin in the codes as well, if using another pin for wiring.
2. MicroPython状态机
The 16-Pixel RGB LED ring light array will be controlled using the scheme outlined in the Raspberry Pi Pico MicroPython getting started document, where we can get started with the tutorial entitled “Using PIO to drive a set of NeoPixel Ring (WS2812 LEDs).” The tutorial contains a script that will be used to create a state machine on the RPi Pico. The state machine will be used to control the LEDs on the ring light using a single pin on the Pico (GPIO13 in the wiring above). The full MicroPython example script can also be found at the Raspberry Pi Pico’s NeoPixel Ring repository.
The code to start the state machine on the Pico's GPIO pin #20 is given below:
import array, time from machine import Pin import rp2 # ############################################ # RP2040 PIO and Pin Configurations ############################################ # # WS2812 LED Ring Configuration led_count = 16 # number of LEDs in ring light PIN_NUM = 13 # pin connected to ring light brightness = 0.5 # 0.1 = darker, 1.0 = brightest @rp2.asm_pio(sideset_init=rp2.PIO.OUT_LOW, out_shiftdir=rp2.PIO.SHIFT_LEFT, autopull=True, pull_thresh=24) # PIO configuration # define WS2812 parameters 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 pre-defined pin # at the 8MHz frequency state_mach = rp2.StateMachine(0, ws2812, freq=8_000_000, sideset_base=Pin(PIN_NUM)) # Activate the state machine state_mach.active(1)
The snippet of code given above will be used for each algorithm used to test the 16-pixel WS2812 LED ring light.
3. ws2812的使用示例
# Example using PIO to drive a set of WS2812 LEDs. import array, time from machine import Pin import rp2 # Configure the number of WS2812 LEDs. NUM_LEDS = 16 PIN_NUM = 6 brightness = 0.2 @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 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) def color_chase(color, wait): for i in range(NUM_LEDS): pixels_set(i, color) time.sleep(wait) pixels_show() time.sleep(0.2) def wheel(pos): # Input a value 0 to 255 to get a color value. # The colours are a transition r - g - b - back to r. if pos < 0 or pos > 255: return (0, 0, 0) if pos < 85: return (255 - pos * 3, pos * 3, 0) if pos < 170: pos -= 85 return (0, 255 - pos * 3, pos * 3) pos -= 170 return (pos * 3, 0, 255 - pos * 3) def rainbow_cycle(wait): for j in range(255): for i in range(NUM_LEDS): rc_index = (i * 256 // NUM_LEDS) + j pixels_set(i, wheel(rc_index & 255)) pixels_show() time.sleep(wait) 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 = (BLACK, RED, YELLOW, GREEN, CYAN, BLUE, PURPLE, WHITE) print("fills") for color in COLORS: pixels_fill(color) pixels_show() time.sleep(0.2) print("chases") for color in COLORS: color_chase(color, 0.01) print("rainbow") rainbow_cycle(0)