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Markdem
Joined: 24 Jun 2005
Posts: 206
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| I2C master\slave |
 Posted: Sat Aug 06, 2005 5:59 am |
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Hi All, after spending the last 4 hours on this fourm and google, i still do not understand what i am doing :(
All i want to do is turn on and off two LED every 2 seconds (this works)
I also want to display whether the LEDs are on or off on a LCD. I can write to the lcd, but my I2C code will not work. I have added a line to show when the slave starts the interrupt, but i never does.
Can somebody please, please help me...
Thank you
Mark
| Code: |
//Master
#include <16f877a.h>
#fuses NOWDT,HS, NOPROTECT, BROWNOUT, NOPUT, NODEBUG, NOLVP
#use delay(clock=20000000)
#use i2c(MASTER, SDA=PIN_C4, SCL=PIN_C3, FORCE_HW)
int light1stat;
int light2stat;
void main()
{
light1stat = 1;
while(1){
light1stat++;
i2c_start();
i2c_write(0xa0);
i2c_write(light1stat);
i2c_stop();
output_low(PIN_D7);
delay_ms(1000);
light2stat = 1;
output_low(PIN_D6);
delay_ms(1000);
light1stat = 0;
output_high(PIN_D7);
delay_ms(1000);
light1stat = 0;
output_high(PIN_D6);
delay_ms(1000);
}
}
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| Code: |
//slave
#include <16f877a.h>
#include <marklcd420.c>
#fuses NOWDT,HS, NOPROTECT, BROWNOUT, NOPUT, NODEBUG, NOLVP
#use delay(clock=20000000)
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, FORCE_HW, address=0xa0)
int light1stat;
int light2stat;
int count;
enable_interrupts(GLOBAL);
enable_interrupts(INT_SSP);
void main()
{
count=1;
lcd_init();
printf(lcd_putc,"Ready");
lcd_gotoxy(1,2);
printf(lcd_putc,"Light1: %U",light1stat);
lcd_gotoxy(1,3);
printf(lcd_putc,"Light2: %U",light2stat);
while(1){
}
}
#INT_SSP
void ssp_interupt ()
{
count++;
lcd_gotoxy(1,4);
printf(lcd_putc,"Count: %U",count);
i2c_start();
light1stat = i2c_read();
//light1stat = i2c_read();
i2c_stop();
}
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Sat Aug 06, 2005 8:14 am |
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| Look at the example programs. Your slave receive is totally wrong. There is an example slave program that will work for you. |
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Markdem
Joined: 24 Jun 2005
Posts: 206
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| Posted: Sun Aug 07, 2005 12:59 am |
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| I have spent the time looking at the example programs, both on the web and in the example folder in CCS, but i dont understand how they work. I need somthing "more" basic. Is the master code at least OK? |
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Markdem
Joined: 24 Jun 2005
Posts: 206
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| Posted: Sun Aug 07, 2005 6:18 am |
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| I have now tired some more debugging on this. My slave programe will never enter the interrupt part. Am i doing somthing wrong here?? |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Sun Aug 07, 2005 6:59 am |
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Look at ex_slave.c That program is meant to emulate a serial eeprom. It could be changed a bit to suit your needs.
I suspect that since you never enter the interrupt, maybe you forgot to add the pullups to the lines.
Also you might try this code out
http://www.ccsinfo.com/forum/viewtopic.php?t=21456 |
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Markdem
Joined: 24 Jun 2005
Posts: 206
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| Posted: Sun Aug 14, 2005 3:16 am |
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Hi All, after retring for a long time to get this working, i am so close, but yet so far.
When i run my new code, it works, but it will only run for a few seconds. After tht, both PIC will just stop. The LEDs on the master stop flashing, and my cound on the LCD on the master will stop. If i run the master without the slave, it will run OK. If i run the slave without the master, it is OK. the problem is only when two chips are on the bus at te same time.
I have looked at all the example programs, but they are all to complex for me and my project, so i cant use them. I just dont understand what they are doing.
The printf statments in the interrupt are only for debugging.
Can sombody please help
Thank you , mark
| Code: |
#include <16f877a.h>
#fuses NOWDT,HS, NOPROTECT, BROWNOUT, NOPUT, NODEBUG, NOLVP
#use delay(clock=20000000)
#use i2c(MASTER, SDA=PIN_C4, SCL=PIN_C3, FORCE_HW)
int light1stat;
int light2stat;
void main()
{
delay_ms(1000);
while(1)
{
i2c_start();
delay_ms(100);
i2c_write(0xa0);
delay_ms(100);
i2c_write(0x07);
delay_ms(100);
i2c_stop();
output_low(PIN_D7);
delay_ms(1000);
light2stat = 1;
output_low(PIN_D6);
delay_ms(1000);
light1stat = 0;
output_high(PIN_D7);
delay_ms(1000);
light1stat = 0;
output_high(PIN_D6);
delay_ms(1000);
}
} |
| Code: |
#include <16f877a.h>
#include <marklcd420.c>
#fuses NOWDT,HS, NOPROTECT, BROWNOUT, NOPUT, NODEBUG, NOLVP
#use delay(clock=20000000)
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0xa0, FORCE_HW)
#use rs232(baud=9600,parity=N,bits=8,xmit=PIN_C6,rcv=PIN_C7)
#byte PIC_SSPBUF=0x13
#byte PIC_SSPADD=0x93
int isrcount;
char dummy;
int light1stat;
int count;
#INT_SSP
void ssp_interupt ()
{
dummy = i2c_read();
printf("sspbuf=%Lx\r\n",PIC_SSPBUF);
printf("sspadd=%Lx\r\n",PIC_SSPADD);
light1stat = i2c_read();
printf("sspbuf2=%Lx\r\n",PIC_SSPBUF);
printf("sspadd2=%Lx\r\n",PIC_SSPADD);
isrcount++;
}
void main()
{
enable_interrupts(GLOBAL);
enable_interrupts(INT_SSP);
lcd_init();
light1stat = 0;
while(1)
{
lcd_gotoxy(1,1);
printf(lcd_putc,"Count: %U",count);
lcd_gotoxy(1,2);
printf(lcd_putc,"Light1: %S",light1stat);
lcd_gotoxy(1,3);
printf(lcd_putc,"dummy: %U",dummy);
lcd_gotoxy(1,4);
printf(lcd_putc,"ISR count: %U",isrcount);
count++;
}
}
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ddscott
Joined: 17 Aug 2005
Posts: 4
Location: Livermore, CA
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| Posted: Tue Aug 23, 2005 9:01 am |
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I don't know if you ever got a solution to your problem, but this is what I use to handle the i2c interrupt. It seems to work as desired, I use an Aardvark I2C emulator to communicate with the slave PIC.
Hope this helps.
| Code: | include "C:\Program Files\PICC\Projects\Bio_Briefcase\i2c_0816.h"
int8 buffer;
boolean rec;
long j;
#int_SSP
void SSP_isr()
{
if (i2c_poll() == TRUE)
{
rec=true;
buffer=i2c_read();
}
}
void check_int()
{
long j;
if (buffer == 0x11)
{
rec = false;
buffer = 0;
for (j=0; j<10000; j++)
{
output_toggle(pin_a1);
delay_ms(1);
}
}
return;
}
void main()
{
int8 data;
long i;
rec=false;
buffer = 0;
setup_adc_ports(NO_ANALOGS|VSS_VDD);
setup_adc(ADC_OFF|ADC_TAD_MUL_0);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(VREF_LOW|-2);
setup_oscillator(False);
enable_interrupts(INT_SSP);
enable_interrupts(GLOBAL);
#priority ssp
while (true) {
data = buffer;
rec=false;
buffer = 0;
if (data == 0x33)
{
data = 0;
for (i=0; i<30000; i++)
{
output_toggle(pin_a0);
delay_ms(1);
if (rec == true)
{
check_int();
}
}
}
}
} |
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ella
Guest
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ddscott
Joined: 17 Aug 2005
Posts: 4
Location: Livermore, CA
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| I2C emulators |
| Posted: Wed Aug 24, 2005 10:28 am |
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It should work just fine with any emulator. Just be wary that the way PIC stores it's address might be different than how the emulator sends the address. If I want my i2c emulator to talk to address 0x20, I need to set the PIC to respond to address 0x40.
I was able to get the PIC to write data to the emulator yesterday. I monitor bit 2 in the SSPSTAT register. When it is a 1, the master has sent a read cmd, and I jump to a routine that writes data. Don't use i2c_start and i2c_stop instructions with the slave.
If you disable the interrupts to perform a high priority task, you need to reset the SSPCON register in software. For the PIC I am using, 16f767, I load the register with 0x36.
Hope this helps. |
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