This document discusses connecting sensors, actuators, and other peripherals to a Raspberry Pi using GPIO pins and programming their functionality using Python. It provides code samples for configuring GPIO pins for input and output, controlling relays connected to GPIO pins, reading from a sensor connected to a GPIO pin, and communicating with an AD/DA board over I2C.

1. Sensors, actuators and the
Raspberry PI
Programming GPIO using Python

2. Raspberry PI vs Desktop PC
• Smaller footprint
• Slower processor

Less memory

Non-standard peripherals

6. Using GPIO – output mode
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM) # refer to GPIO pins
GPIO.setwarnings(False) # ignore warnings
GPIO.setup(pin, GPIO.OUT) # make GPIO pin for output
GPIO.output(pin, GPIO.HIGH) # turn ON GPIO pin
GPIO.output(pin, GPIO.LOW) # turn OFF GPIO pin

7. Using GPIO – input mode
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM) # refer to GPIO pins
GPIO.setwarnings(False) # ignore warnings
GPIO.setup(pin, GPIO.IN) # make GPIO pin for input
val = GPIO.input(pin) # read GPIO pin

11. Relay Connections
Relay board Raspberry PI
GND 6
IN1 15 (GPIO 22)
IN2 16 (GPIO 23)
IN3 18 (GPIO 24)
IN4 22 (GPIO 25)
VCC 2

13. Relay controller sample code
import RPi.GPIO as GPIO
import time
pins = [22,23,24,25]
for p in pins:
GPIO.setup(p, GPIO.OUT)
while True:
for q in pins:
GPIO.output(q, GPIO.HIGH)
time.sleep(5)
for q in pins:
GPIO.output(q, GPIO.LOW)
time.sleep(5)

17. Sensor Connections
Sensor board Raspberry PI
GND 6
OUT 11 (GPIO 17)
VCC 2

18. Sensor sample code
pin = 17
GPIO.setup(pin, GPIO.IN) # make GPIO pin for input
state = GPIO.input(pin) # read GPIO pin
while True:
time.sleep(1)
r = GPIO.input(pin)
if (r != state):
state = r
print "state changed"

21. AD/DA board connections
AD/DA board Raspberry PI
SDA 3
SCL 5
VCC 2
GND 6

22. Convertor sample code
import smbus
def read(a):
bus.read_byte_data(0x48, a)
return bus.read_data(0x48)
bus = smbus.SMBus(1)
control = read(0)
light = read(1)
temperature = read(2)
custom = read(3)
bus.write_byte(self.addr, 99)