The GPIOs (1~20) channels of BPI-Leaf-S3 can be used for ADC analog to digital converter, with a resolution of 12 bit and a maximum voltage measurement of 0 to 3V.
You can perform ADC functions by using a potentiometer. For instance, design a program to control the the color of lamp steplessly.
How to connect
| Potentiometer | Board |
|---|---|
| GND | GND |
| VCC | 3V3 |
| S | GPIO1 |
Micropython
Micropython establishment of operating environment - Banana Pi Wiki (banana-pi.org)
Micropython ADC class machine.ADC documents
In the previous page, we have deigned a program to control neopixel by key interrupts. On this basis, we start to use ADC to implement the same function.
Micropython Code
from machine import Pin,ADC
from neopixel import NeoPixel
from array import array
import time
import micropython
adc1 = ADC(Pin(1),atten=ADC.ATTN_11DB)
micropython.alloc_emergency_exception_buf(100)
p_48 = Pin(48, Pin.OUT)
np = NeoPixel(p_48, 1,bpp=3, timing=1)
p0 = Pin(0,Pin.IN,Pin.PULL_UP)
trig_locks = array('B',[0])
trig_timeticks_list = array('L',[0,0])
count = array('L',[0])
def p0_irq(pin):
if pin.value()==0 and trig_locks[0]==0:
trig_timeticks_list[0]=time.ticks_ms()
trig_locks[0]=1
elif pin.value()==1 and trig_locks[0]==1:
trig_timeticks_list[1]=time.ticks_diff(time.ticks_ms(),trig_timeticks_list[0])
trig_locks[0]=0
if trig_timeticks_list[1] >= 20:
count[0] = count[0] + 1
if count[0] > 8:
count[0] = 0
p0.irq(handler=p0_irq,trigger= Pin.IRQ_FALLING | Pin.IRQ_RISING )
RED = (255, 0, 0)
ORANGE = (255, 100, 0)
YELLOW = (255, 255, 0)
GREEN = (0, 255, 0)
CYAN = (0, 255, 255)
BLUE = (0, 0, 255)
PURPLE = (180, 0, 255)
WHITE = (255, 255, 255)
OFF = (0, 0, 0)
color_list = [RED,ORANGE,YELLOW,GREEN,CYAN,BLUE,PURPLE,WHITE,OFF]
while True:
adc1_read = adc1.read() # 12bit
adc1_read_mv = adc1.read_uv()/1000
adc1_read_u16 = adc1.read_u16() # 16bit
brightness = adc1_read/4095
i = color_list[count[0]]
color = (round(i[0]*brightness),round(i[1]*brightness),round(i[2]*brightness))
np[0] = color
np.write()
print(adc1_read,adc1_read_u16,adc1_read_mv,"mv",count[0],color)
time.sleep(0.1)
video demo:
Banana Pi BPI-Leaf-S3 wiki page: https://wiki.banana-pi.org/BPI-Leaf-S3