PCF8574P with 8 LEDs
A PCF8574 has 8 I/O(Input or Output. All I/Os kann be read/write 1 or 0.)
PinConfiguration:
Pin 1-3==A0-2
Pin 4-7== P0-3
Pin 8== GND/-
Pin 9-12==P4-7
Pin 13== INT
Pin 14== SCL
Pin 15== SDA
Pin 16==Vdd/+5V
A0-2 is for I2C Adress Configuration. The standart Addres of PC8574 is 0x40. If you put any of the Ports to 0/1 (+/-) the Addres changes.
The schematic of the Adres:
0 1 0 0 A2 A1 A0 0.
If A0-2 aro Low(0,-) The address is only 0x40.(01000000 to hexadecimal is 0x40).
As Example:
A0=1
A1=0
A2=1
You must ad the binary value of Ports to 0x40:
101=0x05
0x05+0x40=0x45
P0-7 are the I/O Ports. You can put as an example LEDs or switches on they.
SCL and SDA are the Pins for the I2C Communication. They need an pullup(Resistor to +) of 82k.
INT is the interrupt output. If any Input is changing. It go to High(+). This pin you cann connect to Pin1(ADA). And read as an Touchsensor. So you don't must read any time des PCF8574 per I2C for checking Inputs.
But if Pin1 is set to 9V(e.g. if intalised as Ultrasonic Senor), the IC will be destroid. A
If you want to connect a or more LED(s) to the IC you should connect them with kathode to an Output, und with anode to +. Naturraly the LED needs an resistor
Curcuit:
R1 and R2 have 82k. For R3-10 I had used 470Ohm. I think 220Ohm should work too. But you should use the value you want
.But the maximal current is 180mA.
Building plan für Breadboard
For this tests I had used the Driver from Adam Mokanszki. But you must change the addres to 0x40. (In the Header of the Programm)
Programm for a 8 Channel Knight Rider, using Adam Mokansukis Driver:
Code: Select all
#include "pcf8574llb.nxc"
task main()
{
int port=1;
bool richtung=true;
SetSensorLowspeed(S1);
WritePorts(0xFF); //Alle Ports auf 1(+) setzen.
Wait(100);
while(true)
{
DeletePort(port); //Wechselt Wert 1(+)->0(-)
Wait(500);
WritePort(port); //Schreibt 1(+)
if(richtung==true)
{
port++;
}
else
{
port-=1;
}
if(port==8)
{
richtung=false;
}
if(port==1)
{
richtung=true;
}
}
}pcf8574llb.nxc
Code: Select all
/*************************************************************/
/* */
/* PCF8574Driver for NXC */
/* */
/* Programmed by: Adam Mokanszki */
/* */
/* University of Debrecen Hungary */
/* */
/* ENJOY! :) */
/* */
/*************************************************************/
#ifndef _PCF8574_
#define _PCF8574_
#define PCF8574ID 0x40 //The address of your PCF8574---*******Here you must change the address to 0x40, I have done this yet.
#define PCF8574Port S1 //This is the port on the NXT where the device is connected
void WritePort(char input); //Writing a single port the input is the port number 1-8
void DeletePort(char input); //Deleting a single port the input is the port number 1-8
void WritePorts(byte input); //Writing all ports with one byte
int ReadPort(char input); //Reading a single port the input is the port number 1-8 returning with a logical value in integer: 0,1
int ReadPorts(); //Reading all ports returning with one byte
//That's all what you need to know about this file
void WritePort(char input){
byte cnt = 0x02;
byte I2CMsg[];
byte inbuf[];
byte Address = PCF8574ID;
byte nByteReady = 0;
int result = -1;
int loop;
ArrayBuild(I2CMsg, Address);
Wait(8);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
if (I2CBytes(PCF8574Port, I2CMsg, cnt, inbuf)) {
result = inbuf[1];
}
byte Command = result | (1<<(input-1));
ArrayBuild(I2CMsg, Address, Command);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
I2CWrite(S1, 1, I2CMsg);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
}
void DeletePort(char input){
byte cnt = 0x02;
byte I2CMsg[];
byte inbuf[];
byte Address = PCF8574ID;
byte nByteReady = 0;
int result = -1;
int loop;
ArrayBuild(I2CMsg, Address);
Wait(8);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
if (I2CBytes(PCF8574Port, I2CMsg, cnt, inbuf)) {
result = inbuf[1];
}
byte Command = result ^ (1<<(input-1));
ArrayBuild(I2CMsg, Address, Command);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
I2CWrite(S1, 1, I2CMsg);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
}
void WritePorts(byte input){
byte I2CMsg[];
byte Address = PCF8574ID;
byte Command = input;
byte nByteReady = 0;
int loop;
ArrayBuild(I2CMsg, Address, Command);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
I2CWrite(S1, 1, I2CMsg);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
}
int ReadPort(char input){
byte cnt = 0x02;
byte I2CMsg[];
byte inbuf[];
byte Address = PCF8574ID;
byte nByteReady = 0;
int result = -1;
int loop;
ArrayBuild(I2CMsg, Address);
Wait(8);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
if (I2CBytes(PCF8574Port, I2CMsg, cnt, inbuf)) {
result = inbuf[1];
}
if( result == (result | (1<<input-1)) ){
result = 1;
}
else{
result = 0;
}
if(result==-1){
TextOut(0, LCD_LINE7, "Error: Check the");
TextOut(0, LCD_LINE8, " connection!");
Wait(500);
ClearScreen();
}
return result;
}
int ReadPorts(){
byte cnt = 0x02;
byte I2CMsg[];
byte inbuf[];
byte Address = PCF8574ID;
byte nByteReady = 0;
int result = -1;
int loop;
ArrayBuild(I2CMsg, Address);
Wait(8);
while (loop == STAT_COMM_PENDING) {
loop = I2CStatus(PCF8574Port, nByteReady);
}
if (I2CBytes(PCF8574Port, I2CMsg, cnt, inbuf)) {
result = inbuf[1];
}
if(result==-1){
TextOut(0, LCD_LINE7, "Error: Check the");
TextOut(0, LCD_LINE8, " connection!");
Wait(500);
ClearScreen();
}
return result;
}
#endif