import time
import machine
from machine import Pin
from machine import ADC
# Set LED pin for output
sharpLEDPin = Pin(32, Pin.OUT)
sharpVoPin = ADC(Pin(36))
# ADC Setup
sharpVoPin.atten(ADC.ATTN_11DB)
Vcc = 5
# Output volate at no dust in V
Voc = 0.6 # 0.1 to 1.1
# Sensitivity in units of V per 100ug/m3.
K = 0.5 # 0.425 to 0.575
def readValue():
global Voc
# Turn on ILED
sharpLEDPin.value(0)
# Wait 0.28 ms
# time.sleep_us(280) # Actually, it took 0.4 ms.
time.sleep_us(196) # It was measured about value of 0.28 ms
VoRaw = sharpVoPin.read()
# Wait 0.04 ms
#time.sleep_us(40)
# Turn off ILED
sharpLEDPin.value(1)
# Compute the output voltage in Volts.
Vo = VoRaw / 4095.0 * 5.0
# Convert to Dust Density in units of ug/m3.
dV = Vo - Voc
if dV < 0:
dV = 0
Voc = Vo
dustDensity = dV / K * 100.0
print('VoRaw={}, Vo={} mV, Density={} ug/m3'.format(VoRaw, Vo*1000.0, dustDensity))
#time.sleep_us(10000 - 320)
time.sleep_us(4000)
while True:
readValue()
