Raspberry pi tutorial #3
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This document discusses using an ultrasonic distance sensor with a Raspberry Pi to measure distance. It describes the necessary components, including a Raspberry Pi, breadboard, resistors, and ultrasonic sensor. It explains how to configure the circuit by connecting the sensor to specific Raspberry Pi pins. The document then provides Python code to set up GPIO pins for the trigger and echo signals, send ultrasonic pulses, measure the time until the echo is received, and calculate the distance based on the time elapsed and speed of sound.
Raspberry pi tutorial #3
- 1. 1 Raspberry Tutorial #3 - Measuring the distance - Dong Ho Son POSTECH Pohang, Korea donghoson@postech.ac.kr
- 2. 2 Measuring the distance - Overview Lets use the sensor Ultrasonic distance sensor A sensor that can measure the distance to an object by using sound waves Source: education.rec.ri.cmu.edu/content/electronics/boe/ultrasonic_sensor/1.html
- 3. 3 Measuring the distance - components Lets measure the distance Necessary Components 1 x Raspberry Pi 1 x Breadboard 2 x Resistor 1 x Ultrasonic sensor Jumper cables
- 4. 4 Measuring the distance Circuit Configuration VCC 5V pin Trig the pin GPIO 18 Echo resistors GND Ground pin
- 5. 5 Measuring the distance - Python
- 6. 6 Measuring the distance - Python GPIO.setup(GPIO_TRIGGER, GPIO.OUT) Select GPIO #18 as output pin To make ultrasonic signal GPIO.setup(GPIO_ECHO, GPIO.IN) Select GPIO #24 as input pin To receive the signal GPIO.output(GPIO_TRIGGER, True) time.sleep(0.00001) GPIO.output(GPIO_TRIGGER, False) Send the ultrasonic signal
- 7. 7 Measuring the distance - Python GPIO.input(GPIO_ECHO) High while sending signal Low when signal is returned TimeElapsed = StopTime StartTime Time difference between start and arrival distance = (TimeElapsed * 34300) / 2 Multiply with the sonic speed 34300 cm/s Divide by 2, because there and back
- 8. 8 Measuring the distance - Result Distance is measured!