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Zitat: |
Hallo Herr Horter.
Anbei mein Beispiel zum Setzen der Ausgänge eines
PCF8574(A).
Das Ganze ist für die Microchip PIC-18F-Reihe gechrieben und
wurde mit
dem Microchip C18 Compiler Version 3.10 übersetzt.
Mit freundlichen Grüßen
Heiko W.
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//This routine calls a PCF8574 with adress
"chip1" and send "signal1"
//for output Compiler: MPLAB C18 v3.10
//set configuration bits
#pragma config WDT =OFF //Watchdog timer
disabled
#pragma config MCLRE =ON //Master Clear Reset
enabled
//includes
#include <p18cxxx.h>
#include <delays.h>
#include <stdlib.h>
#include <i2c.h>
//constants
const char signal1 = 0b00000001;
/*
PCF8574 used for OUT / PCF8574A used for IN
PCF8574 slave adress: 0 1 0 0 A2 A1 A0 x -> 64 to 78
PCF8574A slave adress 0 1 1 1 A2 A1 A0 x -> 112 to 126
X = 0 -> write data; X = 1 -> read data
*/
const char chip1 = 64; // =0x40, A0 = 0, A1 =
0, A2 = 0, X = 0
unsigned char send_i2c(unsigned char addr, unsigned char data)
{
IdleI2C();
StartI2C();
IdleI2C();
putcI2C(addr);
IdleI2C();
if ( SSPCON2bits.ACKSTAT ) // test received
ack bit state
{
StopI2C();
return 0; // bus device responded with NOT ACK
}
putcI2C(data);
IdleI2C();
if ( SSPCON2bits.ACKSTAT ) // test received
ack bit state
{
StopI2C();
return 0; // bus device responded with NOT ACK
}
StopI2C();
return 1;
}// of send_i2c
void main (void)
{
/*
Set SDA and SCL
*/
TRISCbits.TRISC3 = 1;
TRISCbits.TRISC4 = 1;
/*
MASTER I2C Master mode
SLEW_OFF Slew rate disabled for 100 kHz mode
*/
OpenI2C(MASTER, SLEW_OFF);
/*
When the SSP is configured in Master mode,
the lower seven bits of SSPADD act as the Baud Rate Generator reload
value.
e.g.:
PIC-Takt (MHz) 4, 8, 10, 12, 16, 20
SSPADD für 100 kHz 9, 19, 24, 29, 39, 49
SSPADD für 400 kHz 2, 4, 6, 7, 9, 12
SSPADD = (FREQ/(4 * SCL))-1
*/
SSPADD = 19; // 100KHz and 8MHz
while(1)
{
if (send_i2c(chip1, signal1))
{
//transmission was ok
}// of if
else
{
// problem while transmitting (no ACK
received)
}// of else
}// of while(1)
}// of main
| PIC-beispielprogramm
für Microchip Entwicklungsumgebung |
 |
pic-8574.c (3 kB)
PIC-Quellcode mit einem Beispiel wie ein PC8574
angesteuert werden kann.
(Bitte mit der rechten Maustaste "speichern unter" wählen! ) |
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