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Problem with hardware i2c pic16f877a

 
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tn88test



Joined: 26 Feb 2013
Posts: 3

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Problem with hardware i2c pic16f877a
PostPosted: Tue Feb 26, 2013 9:45 pm     Reply with quote
I had been successful with software i2c to display timer with ds1307. Now I try with hardware i2c and there is a problem. The i2c bits doesn't automatically cleared by hardware.

example:
My program will stuck here because SSPIF is always 0. If I replace it with delay. The program passed through but displaying wrong result.

Code:
void WaitMSSP(void){
    while(!SSPIF);         // Wait to complete
    SSPIF = 0;
}


The same problem with other SEN, PEN , .... It doesn't automatically cleared by hardware. I check bit SEN, PEN bit to lcd. It's always 1 and not cleared to 0.

Here is my code
Code:
#ifndef _TWI_INCLUDED_
#define _TWI_INCLUDED_

#BYTE SSPSTAT = 0x094
#BIT    BF = SSPSTAT.0
#BIT    UA = SSPSTAT.1
#BIT    R_W = SSPSTAT.2
#BIT    CKE = SSPSTAT.6
#BIT    SMP = SSPSTAT.7
#BYTE SSPCON0 = 0x014
#BIT    SSPM0 = SSPCON0.0
#BIT    SSPM1 = SSPCON0.1
#BIT    SSPM2 = SSPCON0.2
#BIT    SSPM3 = SSPCON0.3
#BIT    CKP = SSPCON0.4
#BIT    SSPEN = SSPCON0.5
#BIT    SSPOV = SSPCON0.6
#BIT    WCOL = SSPCON0.7
#BYTE SSPCON2 = 0x091
#BIT    SEN = SSPCON2.0
#BIT    RSEN = SSPCON2.1
#BIT    PEN = SSPCON2.2
#BIT    RCEN = SSPCON2.3
#BIT    ACKEN = SSPCON2.4
#BIT    ACKDT = SSPCON2.5
#BIT    ACKSTAT = SSPCON2.6
#BIT    GCEN = SSPCON2.7
#BYTE PIR1 = 0x0c
#BIT    TMR1IF = PIR1.0
#BIT    TMR2IF = PIR1.1
#BIT    CCP1IF = PIR1.2
#BIT    SSPIF = PIR1.3
#BIT    TXIF = PIR1.4
#BIT    RCIF = PIR1.5
#BIT    ADIF = PIR1.6
#BIT    PSPIF = PIR1.7
#BYTE SSPBUF = 0x13
#BYTE SSPADD = 0x93

void WaitMSSP(void){
    while(!SSPIF);         // Wait to complete
    SSPIF = 0;
}

void twi_init(void){                                     
    SSPCON0 = ((1 << SSPEN) | (1 << SSPM3));   // Synchronous Serial Port Enable bit, Master mode
    SSPSTAT = (1 << SMP);                  // Standard speed mode (100 kHz and 1 MHz)
    SSPADD = 0x12;                        // clock = 100Khz
}

void twi_start(void){
    SEN = 1;            // Send START condition
    WaitMSSP();
}

void twi_stop(void){
    PEN = 1;             //Send STOP condition                 
    WaitMSSP();
}

void twi_write(int8 tData){
    SSPBUF = tData;         // Send Data
    WaitMSSP();
}

int8 twi_read(int8 ack){
    RCEN = 1;            // Receive Mode
    WaitMSSP();
   
    if (ack != 0){
       ACKDT = 0;
        ACKEN = 1;
        WaitMSSP();
    }else{
       ACKDT = 1;
        ACKEN = 1;
        WaitMSSP();
    }
   
    return SSPBUF;
}

#endif
ezflyr



Joined: 25 Oct 2010
Posts: 1019
Location: Tewksbury, MA

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PostPosted: Tue Feb 26, 2013 11:23 pm     Reply with quote
Hi,

What is your compiler version?

John
Ttelmah



Joined: 11 Mar 2010
Posts: 19520

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PostPosted: Wed Feb 27, 2013 12:53 am     Reply with quote
Er...

What on earth are you trying to do with the instructions like:

SSPCON0 = ((1 << SSPEN) | (1 << SSPM3));

I think you misunderstand how bit variables work in CCS. They are not a reference to the bit 'in' a byte, but a direct reference to a single bit variable. As such SSPEN, will be just 0 or 1, according to what the value in the hardware is at this point. The same with SSPM3. To enable the SSP, just requires:

SSPEN=TRUE;

As such, the port won't be setup as you expect.....

Best Wishes
tn88test



Joined: 26 Feb 2013
Posts: 3

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PostPosted: Wed Feb 27, 2013 2:12 am     Reply with quote
I used PCWHD version 4.104

I have change my code as you suggested. I can see the SEN, PEN bits are cleared by hardware, but SSPIF is not set to 1. My program still stuck at while(!SSPIF);

Code:
void WaitMSSP(void){
   while(!SSPIF);      // Wait to complete
    SSPIF = 0;
}


Here is my new code
Code:
#ifndef _TWI_INCLUDED_
#define _TWI_INCLUDED_

#BYTE SSPSTAT = 0x094
#BIT    BF = SSPSTAT.0
#BIT    UA = SSPSTAT.1
#BIT    R_W = SSPSTAT.2
#BIT    CKE = SSPSTAT.6
#BIT    SMP = SSPSTAT.7
#BYTE SSPCON0 = 0x014
#BIT    SSPM0 = SSPCON0.0
#BIT    SSPM1 = SSPCON0.1
#BIT    SSPM2 = SSPCON0.2
#BIT    SSPM3 = SSPCON0.3
#BIT    CKP = SSPCON0.4
#BIT    SSPEN = SSPCON0.5
#BIT    SSPOV = SSPCON0.6
#BIT    WCOL = SSPCON0.7
#BYTE SSPCON2 = 0x091
#BIT    SEN = SSPCON2.0
#BIT    RSEN = SSPCON2.1
#BIT    PEN = SSPCON2.2
#BIT    RCEN = SSPCON2.3
#BIT    ACKEN = SSPCON2.4
#BIT    ACKDT = SSPCON2.5
#BIT    ACKSTAT = SSPCON2.6
#BIT    GCEN = SSPCON2.7
#BYTE PIR1 = 0x0c
#BIT    TMR1IF = PIR1.0
#BIT    TMR2IF = PIR1.1
#BIT    CCP1IF = PIR1.2
#BIT    SSPIF = PIR1.3
#BIT    TXIF = PIR1.4
#BIT    RCIF = PIR1.5
#BIT    ADIF = PIR1.6
#BIT    PSPIF = PIR1.7
#BYTE SSPBUF = 0x13
#BYTE SSPADD = 0x93

void WaitMSSP(void){
   while(!SSPIF);      // Wait to complete
    SSPIF = 0;
}

void twi_init(void){
   SSPEN = 1;         // Synchronous Serial Port Enable bit,             
   SSPM3 = 1;        // Master mode             
   SMP = 1;            // Standard speed mode (100 kHz and 1 MHz)                          
    SSPADD = 0x12;      // clock = 100KHz
}

void twi_start(void){
    SEN = 1;         // Send START condition
      WaitMSSP();
}

void twi_stop(void){
    PEN = 1;          //Send STOP condition
   WaitMSSP();
}

void twi_write(int8 tData){
    SSPBUF = tData;      // Send Data
   WaitMSSP();
}

int8 twi_read(int8 ack){
    RCEN = 1;         // Receive Mode
    WaitMSSP();
   
    if (ack != 0){
       ACKDT = 0;
        ACKEN = 1;
        WaitMSSP();
    }else{
       ACKDT = 1;
        ACKEN = 1;
        WaitMSSP();
    }
   
    return SSPBUF;
}
#endif
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Wed Feb 27, 2013 9:23 pm     Reply with quote
Why are you doing this ? CCS has built-in hardware i2c routines, which
can be enabled with this statement:
Code:

#use i2c(master, sda=PIN_C4, scl=PIN_C3,  FORCE_HW)

Then use the i2c routines listed in the CCS manual:
http://www.ccsinfo.com/downloads/ccs_c_manual.pdf

Also look at examples of how to use the CCS i2c routines with i2c chips
such as eeproms. The driver files are in this directory:
c:\program files\picc\drivers

Example of eeprom driver file:
24256.c

Make sure you have a 4.7K pull-up resistor on each i2c bus line, sda and scl.
tn88test



Joined: 26 Feb 2013
Posts: 3

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PostPosted: Wed Feb 27, 2013 10:11 pm     Reply with quote
PCM programmer wrote:
Why are you doing this ? CCS has built-in hardware i2c routines, which
can be enabled with this statement:
Code:

#use i2c(master, sda=PIN_C4, scl=PIN_C3,  FORCE_HW)

Then use the i2c routines listed in the CCS manual:
http://www.ccsinfo.com/downloads/ccs_c_manual.pdf

Also look at examples of how to use the CCS i2c routines with i2c chips
such as eeproms. The driver files are in this directory:
c:\program files\picc\drivers

Example of eeprom driver file:
24256.c

Make sure you have a 4.7K pull-up resistor on each i2c bus line, sda and scl.


Thanks! The CCS hardware i2c worked perfectly.
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