update:
habe mich jetzt für das 128x64 OLED entschieden - ist klein, flach, hat bis zu 8 Zeilen zu je 21 Zeichen, 3 verschiedene Schriftgrößen, und läuft im Gegensatz zu den PCF8574-i2c- getriebenen LCD2004 auch gemeinsam mit anderen i2c Geräten bei 400kHz!
Hier ein Testbeispiel, das ich grade für i2c-Testzwecke (RTCDS3231 plus OLED bei 400kHz) geschrieben habe - funktioniert perfekt. Später kommen sowohl der Display-Teil als auch andere langsame Geräte-Zugriffe (RTC, ...) in je einen eigenen low-priority pthread task, damit sie die schnellen Geräte (MCP23017, IMU etc.) nicht durch delays behindern - share and enjoy!
/*
*
* RTC DS3231
* plus OLED Display
*
* ver 0001
*
*/
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdbool.h>
#include <string.h>
#include <termio.h>
#include <wiringPi.h>
#include <wiringPiI2C.h>
#include <ArduiPi_OLED_lib.h>
#include <Adafruit_GFX.h>
#include <ArduiPi_OLED.h>
#include <getopt.h>
#define byte uint8_t
// RTC DS3231
#define ADDR_RTCDS3231 0x68
int fRTCds3231;
// Instantiate the OLED display
ArduiPi_OLED display;
void oled_cls() {
display.clearDisplay();
display.display();
}
void oled_printxy(int x, int y, char * str) {
display.setCursor(x,y);
display.print(str);
display.display();
}
void oled_clrlnxy(int x, int y) {
display.setTextColor(BLACK, BLACK);
oled_printxy( 0, 8, " ");
display.setTextColor(WHITE, BLACK);
}
// mimic conio.h kbhit
bool kbhit(void)
{
struct termios original;
tcgetattr(STDIN_FILENO, &original);
struct termios term;
memcpy(&term, &original, sizeof(term));
term.c_lflag &= ~ICANON;
tcsetattr(STDIN_FILENO, TCSANOW, &term);
int characters_buffered = 0;
ioctl(STDIN_FILENO, FIONREAD, &characters_buffered);
tcsetattr(STDIN_FILENO, TCSANOW, &original);
bool pressed = (characters_buffered != 0);
return pressed;
}
//================================================== ===================================
// Convert normal decimal numbers to binary coded decimal
//================================================== ===================================
byte decToBcd(byte val) { return( (val/10*16) + (val%10) ); }
//================================================== ===================================
// Convert binary coded decimal to normal decimal numbers
//================================================== ===================================
byte bcdToDec(byte val) { return( (val/16*10) + (val%16) ); }
//================================================== ===================================
void setDS3231time( byte year, byte month, byte day,
byte hour, byte minute, byte second, byte dow)
{
// sets time and date data to DS3231
wiringPiI2CWriteReg8(fRTCds3231, 0, decToBcd(second)); // set seconds
wiringPiI2CWriteReg8(fRTCds3231, 1, decToBcd(minute)); // set minutes
wiringPiI2CWriteReg8(fRTCds3231, 2, decToBcd(hour)); // set hours
wiringPiI2CWriteReg8(fRTCds3231, 3, decToBcd(dow)); // ( 1=Sunday, 7=Saturday)
wiringPiI2CWriteReg8(fRTCds3231, 4, decToBcd(day)); // set dayOfMonth (1 to 31)
wiringPiI2CWriteReg8(fRTCds3231, 5, decToBcd(month)); // set month
wiringPiI2CWriteReg8(fRTCds3231, 6, decToBcd(year)); // set year (0 to 99)
}
void getDS3231time( int &year, int &month, int &day,
int &hour, int &minute, int &second, int &dow)
{
second = bcdToDec(wiringPiI2CReadReg8 (fRTCds3231, 0) & 0x7f );
minute = bcdToDec(wiringPiI2CReadReg8 (fRTCds3231, 1) );
hour = bcdToDec(wiringPiI2CReadReg8 (fRTCds3231, 2) & 0x3f );
dow = bcdToDec(wiringPiI2CReadReg8 (fRTCds3231, 3) );
day = bcdToDec(wiringPiI2CReadReg8 (fRTCds3231, 4) );
month = bcdToDec(wiringPiI2CReadReg8 (fRTCds3231, 5) );
year = bcdToDec(wiringPiI2CReadReg8 (fRTCds3231, 6) );
}
char * sdow (int dow) {
switch(dow){
case 1:
return("Sunday");
break;
case 2:
return("Monday");
break;
case 3:
return("Tuesday");
break;
case 4:
return("Wednesday");
break;
case 5:
return("Thursday");
break;
case 6:
return("Friday");
break;
case 7:
return("Saturday");
break;
}
return ("error");
}
//================================================== ===================================
int main() {
static int year, month, day, hour, minute, second, dow;
int i=0, check;
char sbuf[100];
// Oled supported display in ArduiPi_SSD1306.h
// I2C change parameters to fit to your LCD
if ( !display.init(OLED_I2C_RESET, 6) )
exit(EXIT_FAILURE);
display.begin();
// init done
oled_cls();
// test
display.setTextSize(1);
display.setTextColor(WHITE);
display.setTextSize(1);
display.setCursor(0, 0); display.print(" 0 Hello, world!\n");
display.setCursor(0, 8); display.print(" 8 i2c OLED");
display.setCursor(0,16); display.print("16 128x64 addr 0x3c");
display.setCursor(0,24); display.print("24 8x21 char size=1");
display.setCursor(0,32); display.print("32 ");
display.setCursor(0,40); display.print("40 ");
display.setCursor(0,48); display.print("48 456789112345678921");
display.setCursor(0,56); display.print("56 ");
//display.setTextColor(BLACK, WHITE); // 'inverted' text
display.display();
sleep(1);
oled_cls();
// fRTCds3231 = wiringPiI2CSetupInterface( "/dev/i2c-0", ADDR_RTCDS3231 );
fRTCds3231 = wiringPiI2CSetupInterface( "/dev/i2c-1", ADDR_RTCDS3231 );
strcpy(sbuf, "RTC DS3231 \n\n");
printf(sbuf);
oled_printxy( 0, 0, sbuf);
getDS3231time( year, month, day, hour, minute, second, dow);
sprintf(sbuf, "20%02d/%02d/%02d %02d:%02d:%02d", year, month, day, hour, minute, second);
printf(sbuf);
oled_printxy( 0, 8, sbuf);
sprintf(sbuf, " Day of week %1d: ", dow);
printf(sbuf);
printf(sdow(dow) );
printf("\n\n");
printf("*** Set Date/Time: enter 1 *** \n");
printf("*** else: display time *** \n\n");
oled_printxy( 0,24, "Set DateTime enter 1");
oled_printxy( 0,32, "else: display time");
i = getchar();
//debug
//printf("%d \n", i);
while (i=='1') {
// get string yy mm dd hh mm ss dw : gets() ?
printf("yy mm dd hh mm ss dw (DayOfWeek) \n");
check=scanf("%d %d %d %d %d %d %d", &year, &month, &day, &hour, &minute, &second, &dow);
getchar();
printf("check=%d\n", check);
if(check==7) {
sprintf(sbuf, "20%02d/%02d/%02d %02d:%02d:%02d", year, month, day, hour, minute, second);
printf(sbuf);
oled_printxy( 0, 8, sbuf);
printf(" Day of week %1d: ", dow);
printf(sdow(dow) );
printf("\n");
setDS3231time( year, month, day, hour, minute, second, dow );
}
oled_cls();
printf("RTC DS3231 \n");
oled_printxy( 0, 0, sbuf);
printf("*** Set Date/Time: enter 1 *** \n");
printf("*** else: display time *** \n\n");
oled_printxy( 0,24, "Set DateTime enter 1");
oled_printxy( 0,32, "else: display time");
i=0;
i = getchar();
}
oled_cls();
oled_printxy( 0, 0, "RTC DS3231 - quit:ESC");
while(1) {
getDS3231time( year, month, day, hour, minute, second, dow);
sprintf(sbuf, "20%02d/%02d/%02d %02d:%02d:%02d", year, month, day, hour, minute, second);
printf(sbuf);
oled_clrlnxy( 0,16);
oled_printxy( 0,16, sbuf);
printf(" Day of week %1d: ", dow);
printf(sdow(dow) );
printf("\n");
if (kbhit())
{
int c = getchar();
if(c==27) break;
}
sleep(1);
}
oled_cls();
return (0);
}