GPIO pins mind bogling error

Question

Raspberry pi 3 b+

I'm trying to make an Obstacle avoidance obstacles.

It's a very simple project. I tried with one ultra sonic sensor, it worked. Gave me the distance which i could further manipulate to avoid distance.

It wasn't very good, it collided a lot specially when it came at an angle to the wall or an object.

I then tried to mesh a network of Sensors (3 Ultra sonic sensor and 2 IR sensors) to work in combination for better obstacle avoidance. Seemed simple enough as well.

But I'm not able to run the other two ultra sonic sensors. Which is weird considering i set them up exactly the same.

I ran the same code just changing the GPIO pin number's that i have connected the ECHO and TRIG pin to.

the working pins were (GPIO.BOARD) 7, 11

I connected the TRIG and ECHO pins on 13,15 && 16,18

They don't seem to work. If i connect any sensors's pin to 7,11 they work. Other than these two pins I'm getting no response. I tried all 3 Sensors and the all work at 7,11 pins.

SO,

• The sensors work
• The connections are correct (VCC, GND)
• The code works

Need help. I have this feeling that the solution would be something very simple.

GPIO_TRIGGER = 7
GPIO_ECHO = 11

If i change them to

GPIO_TRIGGER = 13
GPIO_ECHO = 15

It doesnt work.. the same sensor that was working with the same code on 7,11

import RPi.GPIO as GPIO

import time

GPIO.setwarnings(False)

def distance(): GPIO.setmode(GPIO.BOARD)

GPIO_TRIGGER = 13
GPIO_ECHO = 15


GPIO.setup(GPIO_TRIGGER, GPIO.OUT)
GPIO.setup(GPIO_ECHO, GPIO.IN)
GPIO.output(GPIO_TRIGGER, False)

GPIO.output(GPIO_TRIGGER, True)

time.sleep(0.00001)

GPIO.output(GPIO_TRIGGER, False)

starttime = time.time()
stoptime = time.time()

while GPIO.input(GPIO_ECHO) == 0:
    starttime = time.time()

while GPIO.input(GPIO_ECHO) == 1:
    stoptime = time.time()

timeElapsed = stoptime - starttime
distance = (timeElapsed * 34300)/2

return distance
try:
while True:
    far = distance()
    far = far - 1
    print('Distance = %.lf cm*' %far)

except:
KeyboardInterrupt
print('Stop sucessfull')
GPIO.cleanup()

Answer 1

Can you add your circuit diagram? Which sensor are you using? If it is the HC-SR04, the echo pin is rated at 5V and you will need a voltage divider. Not mentioned in your description if you used the divider. The Raspberry Pi GPIO pins are not 5V tolerant and can be damaged. See: https://www.modmypi.com/blog/hc-sr04-ultrasonic-range-sensor-on-the-raspberry-pi.

Edit to Add: Most likely the problem is due to the fact that the voltage divider as you have it right now is only putting out 1.67 V which is less than the 2V needed.