I2C MSSP PIC18/DS1339 Read() HELP??

bogzao · Joined: 07 Mar 2007 Posts: 4 Location: Portugal, Aveiro

I´m trying to make (MSSP) I2C driver to communicate a pic18f6722 with a RTC DS1339. The original code is in C and it´s running well.. I get good readings from the RTC.
Do to memory problems, I´m trying to convert C read function to ASM to reduce the code and free some program memory. But I found this task dificult. I only tried to make a start condition replacing the "i2c_start()" with a "BSF SSPCON2,SEN" as shown above, and I dont get any readings and no Start. The program get this result:

..
START I2C
START I2C
START I2C
START I2C
START I2C
Error I2C
..

Anyone knows how to help me..
I forgot to mention I´m a beginner in assembler programming and sorry for my english.
Best Regards,

Bio

Part of the Code:
----------------

#use delay(clock=20000000)
#use i2c(Master, SLOW, sda=PIN_C4, scl=PIN_C3)
...

#define READ 1
#define WRITE 0

#byte SSPCON2 = 0xFC5

#define SEN 0

...

void READ_I2C(unsigned int8 ADR_SLAVE,unsigned int8 ADR_REG,char PTR_DATA[],unsigned int8 LENGTH)
{
unsigned int8 i;
unsigned int Slave_ack=1;
unsigned int time_count=0;
while ((Slave_ack==1)&&(time_count<5))
{
time_count++;
do {

#asm
CLRF SSPCON2
BSF SSPCON2,SEN // SEEMS A ERROR!!
#endasm
fprintf(CON,"\r\nSTART I2C");

//i2c_start(); ****
Slave_ack=i2c_write(ADR_SLAVE | WRITE);
if (Slave_ack){
i2c_stop();
break;
}
fprintf(CON,"\r\nError I2C 1"); // ERROR Debug

if (ADR_SLAVE==0xB8)
delay_ms(5);
Slave_ack=i2c_write(ADR_REG);
if (Slave_ack){
i2c_stop();
break;
}
fprintf(CON,"\r\nError I2C 2"); // ERROR Debug

if (ADR_SLAVE==0xB8)
delay_ms(5);
i2c_start();
Slave_ack=i2c_write(ADR_SLAVE | READ);
if (Slave_ack){
i2c_stop();
break;
}
fprintf(CON,"\r\nError I2C 3"); // ERROR Debug

for (i=ADR_REG;i<(ADR_REG+LENGTH-1);i++)
PTR_DATA=i2c_read(1);
PTR_DATA=i2c_read(0);
i2c_stop();

} while (time_count<5);
}
if (time_count==5)
{
#ifdef DEBUG_I2C
if (Consola_Enable())
fprintf(CON,"\r\nError I2C");
#endif
}
}

**** The result of the compiler (CCS PCH C Compiler, Version 3.224) just of I2C_READ():
.................... i2c_start();
698A: BSF F94.4
698C: MOVLW 02
698E: MOVWF 00
6990: DECFSZ 00,F
6992: BRA 6990
6994: BSF F94.3
6996: MOVLW 03
6998: MOVWF 00
699A: DECFSZ 00,F
699C: BRA 699A
699E: BCF F8B.4
69A0: BCF F94.4
69A2: MOVLW 02
69A4: MOVWF 00
69A6: DECFSZ 00,F
69A8: BRA 69A6
69AA: BCF F8B.3
69AC: BCF F94.3

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

bogzao · Joined: 07 Mar 2007 Posts: 4 Location: Portugal, Aveiro

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Your code is doing bit-banging. The way to get reduced code size is
to use the hardware MSSP, which is available on pins C4 and C3.
You have to tell the compiler to use the hardware i2c library functions
by using the FORCE_HW parameter in the #use i2c() statement.

Did you do this ?

If you did, and it's still generating software i2c ASM code, then
post your compiler version.

bogzao · Joined: 07 Mar 2007 Posts: 4 Location: Portugal, Aveiro

I didnt know that.. I did that and the result from the compiler is..
(CCS PCH C Compiler, Version 3.224)

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

bogzao · Joined: 07 Mar 2007 Posts: 4 Location: Portugal, Aveiro

Yes, you´re right it´s a High voltage programmer. I´ve changed to NOLVP.
The program works!
I´m trying to change C to Asm, but I found some problems in some code parts.
When I change:
- Slave_ack=i2c_write(ADR_SLAVE | WRITE);
- Slave_ack=i2c_write(ADR_REG);

the result is:

PCM programmer · Joined: 06 Sep 2003 Posts: 21708