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WS2812 LED Control (neopixel)

Overview​

This article explains how to use the expansion header of the Firefly T1 development board together with the neopixel library to precisely control and drive WS2812-series RGB smart LEDs.

Hardware Requirements​

Prepare the following hardware components:

  • Firefly T1 Main Unit: Acts as the core controller, providing processing power and interface support.
  • 5-Pin Terminal: Used to connect signal and power lines, ensuring a stable electrical connection.
  • 5V WS2812 LED(s) or Strip: LEDs or strips conforming to the WS2812 specification. The exact count and length can be adjusted according to your project needs.

Software Setup​

Controlling the LEDs relies on the neopixel library. Before use, the system power must be initialized. Follow these steps:

  1. Power Management Module Configuration

    Use the Firefly T1 Power Management (pm) API to set VCC to "output" mode with 5V output, satisfying the WS2812 LED supply requirements.

  2. GPIO Pin Level Control

    Set the GPIO43 pin to "low" level to turn on the external P-MOS control circuit. This connects the VCC 5V rail to the PIN output.

Application Examples​

Power Initialization​

# 打开电源管理的VCC输出。
import pm
pm.init()
pm.set_power_state(pm.VCC_OUTPUT)


# 接通电源引脚
from machine import Pin
enable_pin = Pin(43,Pin.OPEN_DRAIN)  # 初始化VCC引脚为"高阻态"
enable_pin.value(0) # 设置为低电平，接通p-mos，VCC使能输出

Initialize neopixel​

import neopixel
MAX_RESOLUTION = 480 # 定义最大灯珠数
np = neopixel.NeoPixel(Pin(13), MAX_RESOLUTION)  # 设置LED控制引脚

Light Up WS2812 LEDs​

In the neopixel library, np[i] controls the color of the i-th LED. Usage:

# 设置第 0 颗灯珠为红色
np[0] = (255, 0, 0)

# 设置第 1 颗灯珠为绿色
np[1] = (0, 255, 0)

# 设置第 2 颗灯珠为蓝色
np[2] = (0, 0, 255)

# 应用更改，使颜色生效
np.write()

Full Example​

# 打开电源管理的VCC输出。
import pm
pm.init()
pm.set_power_state(pm.VCC_OUTPUT)


# 接通电源引脚
from machine import Pin
enable_pin = Pin(43,Pin.OPEN_DRAIN)  # 初始化VCC引脚为"高阻态"
enable_pin.value(0) # 设置为低电平，接通p-mos，VCC使能输出

import neopixel
MAX_RESOLUTION = 480 # 定义最大灯珠数
np = neopixel.NeoPixel(Pin(13), MAX_RESOLUTION)  # 设置LED控制引脚



# 设置第 0 颗灯珠为红色
np[0] = (255, 0, 0)

# 设置第 1 颗灯珠为绿色
np[1] = (0, 255, 0)

# 设置第 2 颗灯珠为蓝色
np[2] = (0, 0, 255)

# 应用更改，使颜色生效
np.write()

Notes:

  • np[i] = (R, G, B): Sets the color of the i-th LED. R, G, B are red, green, and blue brightness values in the range 0-255.
  • np.write(): Sends the configured colors to the LEDs. No changes take effect until this is called.

With this, you can control each LED's color individually via np[i]!

AI Programming​

API Code Template​

# 打开电源管理的VCC输出。
import pm
pm.init()
pm.set_power_state(pm.VCC_OUTPUT)


# 接通电源引脚
from machine import Pin
enable_pin = Pin(43,Pin.OPEN_DRAIN)  # 初始化VCC引脚为"高阻态"
enable_pin.value(0) # 设置为低电平，接通p-mos，VCC使能输出

import neopixel
MAX_RESOLUTION = 480 # 定义最大灯珠数
np = neopixel.NeoPixel(Pin(13), MAX_RESOLUTION)  # 设置LED控制引脚



# 设置第 0 颗灯珠为红色
np[0] = (255, 0, 0)

# 设置第 1 颗灯珠为绿色
np[1] = (0, 255, 0)

# 设置第 2 颗灯珠为蓝色
np[2] = (0, 0, 255)

# 应用更改，使颜色生效
np.write()

Prompt Format​

  1. Provide the code template: Send the template directly.
  2. State your requirements clearly: Describe the desired functionality in concrete terms — the more specific, the better.
  3. Describe expected output or behavior: e.g. run results, reactive changes, etc.

Example Prompt​

info

Please write a MicroPython program running on the Firefly T1:

  • Hardware description:
    • WS2812 LED strip, 60 LEDs
    • Data wire connected to PIN5 (i.e. pin number 13)
  • Feature requirements:
    • Fill the entire strip with a rainbow color gradient
    • Each LED has a different color, creating a smooth transition
    • Keep the strip lit once colored; no looping animation
  • Implementation notes:
    • Include power initialization (VCC output, GPIO43 P-MOS control)
    • Use the neopixel library
    • Provide the code directly, ready to copy and run
  • Expected result:
    • All LEDs light up, showing a rainbow gradient