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Question about I2C

 
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Student16



Joined: 02 Jan 2021
Posts: 5

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Question about I2C
PostPosted: Wed Jan 13, 2021 11:29 am     Reply with quote

Hi I have problems with I2C, I want to send an int value from the master to the slave and display this value on a LCD connnected to the slave.

But I am getting unexpected results (the LCD displays 11, which I think is caused by I2C).

See my code below, am I doing something wrong?

MASTER:
Code:

#include <16F877A.h>
#fuses XT, NOWDT,PUT,BROWNOUT,NOLVP
#use delay(clock=4000000)
#use i2c(Master, sda=PIN_C4, scl=PIN_C3)

#define REEDCONTACT0 PIN_A1
#define REEDCONTACT1 PIN_A2
#define REEDCONTACT2 PIN_A3
#define REEDCONTACT3 PIN_A4
#define DRUKKNOP_FRONT0 PIN_C0
#define DRUKKNOP_FRONT1_OMLAAG PIN_C1
#define DRUKKNOP_FRONT1_OMHOOG PIN_C2
#define DRUKKNOP_FRONT2_OMLAAG PIN_C5
#define DRUKKNOP_FRONT2_OMHOOG PIN_C6
#define DRUKKNOP_FRONT3 PIN_C7
#define DRUKKNOP_FRONT_NOODKNOP PIN_A5
#define DRUKKNOP_LIFT0 PIN_B0
#define DRUKKNOP_LIFT1 PIN_B1
#define DRUKKNOP_LIFT2 PIN_B2
#define DRUKKNOP_LIFT3 PIN_B3
#define DRUKKNOP_LIFT_NOODKNOP PIN_B4
#define TEMP_SENSOR PIN_A0

void main (){
   
   while(1){
      if(input(REEDCONTACT0) == 1){
         i2c_start();
         i2c_write(0x12);
         i2c_write(1); 
         i2c_stop(); 
      }
      if(input(REEDCONTACT1) == 1){
         i2c_start();
         i2c_write(0x12);
         i2c_write(2); 
         i2c_stop(); 
      }
      if(input(REEDCONTACT2) == 1){
         i2c_start();
         i2c_write(0x12);
         i2c_write(3); 
         i2c_stop(); 
      }
      if(input(REEDCONTACT3) == 1){
         i2c_start();
         i2c_write(0x12);
         i2c_write(4); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_FRONT0) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(5); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_FRONT1_OMLAAG) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(6); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_FRONT1_OMHOOG) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(7); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_FRONT2_OMLAAG) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(8); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_FRONT2_OMHOOG) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(9); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_FRONT3) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(10); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_FRONT_NOODKNOP) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(11); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_LIFT0) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(12); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_LIFT1) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(13); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_LIFT2) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(14); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_LIFT3) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(15); 
         i2c_stop(); 
      }
      if(input(DRUKKNOP_LIFT_NOODKNOP) == 0){
         i2c_start();
         i2c_write(0x12);
         i2c_write(16); 
         i2c_stop(); 
      }
   }
}


SLAVE:
Code:

#include <16F877A.H>
#fuses XT, NOWDT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0x12)

//LCD module connections
#define LCD_RS_PIN PIN_C0
#define LCD_RW_PIN PIN_C5
#define LCD_ENABLE_PIN PIN_C6
#define LCD_DATA4 PIN_C7
#define LCD_DATA5 PIN_E0
#define LCD_DATA6 PIN_E1
#define LCD_DATA7 PIN_E2
//End LCD module connections

#define GROENE_LED0 PIN_A1
#define GROENE_LED1 PIN_A3
#define GROENE_LED2 PIN_A5
#define GROENE_LED3 PIN_B1
#define RODE_LED0 PIN_A0
#define RODE_LED1 PIN_A2
#define RODE_LED2 PIN_B4
#define RODE_LED3 PIN_B0

#include <lcd.c>

//====================================

int sensor;

#INT_SSP
void ssp_interrupt(){
   sensor = i2c_read(0);
}

void print_op_LCD(int sensorwaarde){
   lcd_putc('\f');
   lcd_putc("Waarde:");
   lcd_gotoxy(1, 2);
   printf(lcd_putc, "%d", sensorwaarde);
   delay_ms(1000);
}

void main(){
   enable_interrupts(INT_SSP);
   enable_interrupts(GLOBAL);
   
   lcd_init();
   lcd_putc("\fReady...\n");
   
   while(1){
      if(sensor == 1){
         output_high(GROENE_LED0);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(GROENE_LED0);
      }
      if(sensor == 2){
         output_high(GROENE_LED1);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(GROENE_LED1);
      }
      if(sensor == 3){
         output_high(GROENE_LED2);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(GROENE_LED2);
      }
      if(sensor == 4){
         output_high(GROENE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(GROENE_LED3);
      }
      if(sensor == 5){
         output_high(RODE_LED0);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED0);
      }
      if(sensor == 6){
         output_high(RODE_LED1);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED1);
      }
      if(sensor == 7){
         output_high(RODE_LED2);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED2);
      }
      if(sensor == 8){
         output_high(RODE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED3);
      }
      if(sensor == 9){
         output_high(RODE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED3);
      }
      if(sensor == 10){
         output_high(RODE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED3);
      }
      if(sensor == 11){
         output_high(RODE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED3);
      }
      if(sensor == 12){
         output_high(RODE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED3);
      }
      if(sensor == 13){
         output_high(RODE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED3);
      }
      if(sensor == 14){
         output_high(RODE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED3);
      }
      if(sensor == 15){
         output_high(RODE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED3);
      }
      if(sensor == 16){
         output_high(RODE_LED3);
         print_op_LCD(sensor);
         delay_ms(1000);
         output_low(RODE_LED3);
      }
   }
}
Ttelmah



Joined: 11 Mar 2010
Posts: 16633

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PostPosted: Wed Jan 13, 2021 11:51 am     Reply with quote

Seriously, look at the I2C slave example (or look here). The first I2C
interrupt is when the address is received, not your data byte....
temtronic



Joined: 01 Jul 2010
Posts: 7785
Location: Greensville,Ontario

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PostPosted: Wed Jan 13, 2021 2:46 pm     Reply with quote

hmmmm I was thinking that, for example..
Quote:

if(sensor == 1){
output_high(GROENE_LED0);
print_op_LCD(sensor);
delay_ms(1000);
output_low(GROENE_LED0);

The value for 'sensor' is 1 same as 0b00000001.

This is NOT the same as the printable ASCII '1' character( (49 decimal, 0x31).
You would have to add 48 to the sensor value.

I don't know if the function print_op_LCD() does a conversion to translate the '1' into a printable '1'.
Student16



Joined: 02 Jan 2021
Posts: 5

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Question about I2C
PostPosted: Wed Jan 13, 2021 6:37 pm     Reply with quote

temtronic wrote:
hmmmm I was thinking that, for example..
Quote:

if(sensor == 1){
output_high(GROENE_LED0);
print_op_LCD(sensor);
delay_ms(1000);
output_low(GROENE_LED0);

The value for 'sensor' is 1 same as 0b00000001.

This is NOT the same as the printable ASCII '1' character( (49 decimal, 0x31).
You would have to add 48 to the sensor value.

I don't know if the function print_op_LCD() does a conversion to translate the '1' into a printable '1'.


It does with the following line:
printf(lcd_putc, "%d", sensorwaarde);
temtronic



Joined: 01 Jul 2010
Posts: 7785
Location: Greensville,Ontario

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PostPosted: Thu Jan 14, 2021 5:20 am     Reply with quote

Yes, that's because that function 'translates' the binary '1' into a printable character '1'.
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