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brief introduction

Two colors LED The lamp （ Double primary color LED The lamp ）, Means that the module can only display 2 Color , Usually red and green , There can be three states ： destroy 、 Color 1 bright 、 Color 2 bright ; Depending on the color combination , Divided into red and blue , Yellow and blue , Red and green, etc .

Two colors LED Often used to indicate the State ： For example, red indicates that the device is abnormal , Green means normal .

One 、 Experimental results

Two 、 Components

1、 Raspberry pie motherboard *1

2、 Raspberry pie power *1

3、40P ffc *1

4、 Two colors LED modular *1

5、 Breadboard *1

6、 Several jumpers

3、 ... and 、 Experimental principle

Insert the pin S（ green ） And the middle pin R（ Red ） Connected to raspberry pie GPO On the interface , Programming raspberry pie , take LED The color changes from red to green , And then use PWM Mix other colors .
The schematic diagram of the module is as follows ：

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Four 、 The experimental steps

Build a circuit ：

Raspberry pie	Breadboard	Two colors LED modular
GPIO1	GPIO18	G(S)
GPIO0	GPIO17	R( middle )
GND	GND	GND

5、 ... and 、 Code implementation

WM The frequency of ：P Determines the output digital signal on （1） and off（0 ） Switching speed of , The higher the frequency is. , The faster you switch .

Duty cycle ： It refers to... In a series of ideal pulses , The ratio of the duration of the positive pulse to the total period of the pulse , Used to adjust the brightness of the lamp .

import RPi.GPIO as GPIO
import time

colors = [0xFF00, 0x00FF, 0x0FF0, 0xF00F]
makerobo_pins = (11, 12)  # PIN Pin dictionary 

GPIO.setmode(GPIO.BOARD)     #  Use actual physical pins to GPIO mouth 
GPIO.setwarnings(False)      #  Remove GPIO Mouth warning 
GPIO.setup(makerobo_pins, GPIO.OUT)   #  Set up Pin The mode is output mode 
GPIO.output(makerobo_pins, GPIO.LOW)  #  Set up Pin The pin is low level (0V) close LED

p_R = GPIO.PWM(makerobo_pins[0], 2000)  #  Set the frequency to 2KHz
p_G = GPIO.PWM(makerobo_pins[1], 2000)  #  Set the frequency to 2KHz

#  The initialization duty cycle is 0(led close )
p_R.start(0)     
p_G.start(0)

def makerobo_pwm_map(x, in_min, in_max, out_min, out_max):
    return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min

def makerobo_set_Color(col):   #  for example :col = 0x1122
    R_val = col  >> 8
    G_val = col & 0x00FF
    #  hold 0-255 The scope of is reduced to 0-100 Between 
    R_val = makerobo_pwm_map(R_val, 0, 255, 0, 100)
    G_val = makerobo_pwm_map(G_val, 0, 255, 0, 100)

    p_R.ChangeDutyCycle(R_val)     #  Change the duty cycle 
    p_G.ChangeDutyCycle(G_val)     #  Change the duty cycle 

#  Call the loop function 
def makerobo_loop():
    while True:
        for col in colors:
            makerobo_set_Color(col)
            time.sleep(0.5)
#  Release resources 
def makerobo_destroy():
    p_G.stop()
    p_R.stop()
    GPIO.output(makerobo_pins, GPIO.LOW)    #  Close all LED
    GPIO.cleanup()                          #  Release resources 

#  Program entrance 
if __name__ == "__main__":
    try:
        makerobo_loop()       #  Call the loop function 
    except KeyboardInterrupt:  #  When pressed Ctrl+C when , Will perform destroy() Subroutines .
        makerobo_destroy()    #  Release resources