Arduino PCF8575 8xLED LM35 Thermometer
My code:
#include <Wire.h>
// Set I2C address
int address = 0x20;
int samples = 2;
int collectDelay = 1000;
int ledPin = 13;
int tempPin = 0;
float tempC = 0;
void setup() {
pinMode(ledPin, OUTPUT);
Wire.begin();
pf575_write(word(B11111111,B11111111));
delay(200);
pf575_write(word(B00000000,B11111111));
delay(200);
pf575_write(word(B11111111,B11111111));
delay(200);
pf575_write(word(B00000000,B11111111));
delay(200);
pf575_write(word(B11111111,B11111111));
delay(1000);
}
void loop() {
tempC = 0;
for(int i = 0; i <= (samples - 1); i++) {
tempC = tempC + ((5.0 * analogRead(tempPin) * 100.0) / 1024.0);
digitalWrite(ledPin, HIGH);
delay((collectDelay / 2));
digitalWrite(ledPin, LOW);
delay((collectDelay / 2));
}
tempC = tempC / (float)samples;
if(tempC > 21) {
pf575_write(word(B11111110,B11111111));
}
if(tempC > 23) {
pf575_write(word(B11111100,B11111111));
}
if(tempC > 25) {
pf575_write(word(B11111000,B11111111));
}
if(tempC > 27) {
pf575_write(word(B11110000,B11111111));
}
if(tempC > 29) {
pf575_write(word(B11100000,B11111111));
}
if(tempC > 31) {
pf575_write(word(B11000000,B11111111));
}
if(tempC > 33) {
pf575_write(word(B10000000,B11111111));
}
if(tempC > 35) {
pf575_write(word(B00000000,B11111111));
}
}
void pf575_write(uint16_t data) {
Wire.beginTransmission(address);
Wire.write(highByte(data));
Wire.write(lowByte(data));
Wire.endTransmission();
}Arduino PF575 I²C I/O port expander blink example
I got some TI PCF8575 I²C I/O expander devices some years ago and never gave them a try. Yesterday I did... In the title they are named PF575, this is because this is what is printed on the device.
I wrote code for making a LED blink using the I/O expander as simple as possible.
Here you see my setup on a breadboard. On the left is the LED connected via a PNP transistor for voltage control.
I only had 24-SSOP packages so I needed to solder the PCF8575 to a DIP adapter for making it breadboard friendly.
My code:
#include <Wire.h>
/**
* Arduino PF575/PCF8575 I2C I/O port exapander LED blink example
*
* Setup:
*
* 1. Connect A0, A1 and A2 to GND to set the address to 0x20.
* 2. Connect SDL and SCL to the Arduino's I2C bus.
* 3. Connect a LED to the P0 port of the I2C exapander.
* In my setup I am using a PNP Transistor connected to 5V unsing
* an resistor, the LED and the Arduino to make sure the LED gets
* a current from Vcc and not from the I2C exapander port.
*
* This code is trying to explain how it works as simple as possible.
* More detailed examples are found on the web. Search for pcf8575 and
* you will find what you want.
*/
// Set I2C address
int address = 0x20;
void setup(){
Wire.begin();
// Set all ports as output
pf575_write(word(B11111111,B11111111));
}
void loop(){
// Set port P0 on
pf575_write(word(B00000000,B00000001));
delay(1000);
// Set port P0 off
pf575_write(word(B00000000,B00000000));
delay(1000);
}
// Function for writing two Bytes to the I2C expander device
void pf575_write(uint16_t data) {
Wire.beginTransmission(address);
Wire.write(lowByte(data));
Wire.write(highByte(data));
Wire.endTransmission();
}Some links:
Website refactored!
I refactored this website last night. Please do not wonder why things are different. Some features are gone, some will come back... I need some time for it but for now I am very excited about the result.
I will update this post from time to time in the next days...