This is failure story about converting c code to python.
There is GPIO controlling library on Python such as RPI, wiringPI.
But they are not enough to controlling high frequency data.
some people already investigate about it.
http://codeandlife.com/2012/07/03/benchmarking-raspberry-pi-gpio-speed/
Follow code return wrong values because frequency.
So I should hybrid c++ and python codes.
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| import RPi.GPIO as GPIO | |
| from array import * | |
| from time import sleep | |
| usleep = lambda x: sleep(x/2000000.0) | |
| def readDHT11(): | |
| MAXTIMINGS = 85 | |
| DHTPIN = 4 | |
| laststate = GPIO.HIGH | |
| j = 0 | |
| GPIO.setmode(GPIO.BCM) | |
| GPIO.setwarnings(False) | |
| dht11_dat = array('i', [0,0,0,0,0]) | |
| GPIO.setup(DHTPIN, GPIO.OUT) | |
| GPIO.output(DHTPIN, GPIO.LOW) | |
| sleep(0.025) | |
| GPIO.output(DHTPIN, GPIO.HIGH) | |
| GPIO.setup(DHTPIN, GPIO.IN) | |
| for i in range(0, MAXTIMINGS): | |
| counter = 0; | |
| while GPIO.input(DHTPIN) == laststate: | |
| counter = counter + 1 | |
| if counter == 255: | |
| break | |
| laststate = GPIO.input(DHTPIN) | |
| if counter == 255: | |
| break | |
| if (i >= 4) and (i % 2 == 0): | |
| index = (int)(j/8) | |
| dht11_dat[index] = dht11_dat[index] << 1 | |
| if counter > 16: | |
| dht11_dat[index] = dht11_dat[index] | 1 | |
| j = j + 1 | |
| print("j= {0}".format(j)) | |
| condition1 = (j >= 40) | |
| condition2 = (dht11_dat[4] == | |
| ((dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xff)) | |
| condition3 = ((dht11_dat[0] != 0) and (dht11_dat[2] != 0)) | |
| if (condition1 and condition2 and condition3): | |
| f = dht11_dat[2] * 9.0 / 5.0 + 32; | |
| print("Humidity = {0}.{1} % Temperature = {2}.{3} *C ({4} *F)".format(dht11_dat[0], dht11_dat[1], dht11_dat[2], dht11_dat[3], f)) | |
| print("{0}, {1}, {2}, {3}, {4}".format(dht11_dat[0], dht11_dat[1], dht11_dat[2], dht11_dat[3], dht11_dat[4] )) | |
| def motion_callback(channel): | |
| print("motion detect = {0}".format(GPIO.input(23))) | |
| def registerMotionCallback(): | |
| MOTION = 23 | |
| GPIO.setup(MOTION, GPIO.IN) | |
| GPIO.add_event_detect(MOTION, GPIO.RISING) | |
| GPIO.add_event_callback(MOTION, motion_callback) | |
| def main(): | |
| GPIO.setmode(GPIO.BCM) | |
| registerMotionCallback() | |
| while True: | |
| readDHT11() | |
| sleep(1) | |
| if __name__ == "__main__": | |
| main( |
