Pic18f2420 to DS1377 RTC

[kolbep]

Hi All.

This one has been plaguing me for 2 evenings now.
I have a Pic18F2420, and a DS1377 RTC.
The DS1377 is running fine (its default is to have sqw output at the Crystal frequency (which is 32.768Khz.  I confirmed that this output is spot on with a frequency counter.

I have connected it to my PIC micro, and can scope data on the I2C Clock and data lines, (Analogue scope, so just catch a blip of it, but I can see that it is a clocked signal).

But I cannot get the RTC to change its SQW output to be anything other than the default.
I have even tried to make the bar EOSC register high, to shutdown the oscillator, but nothing, nada.

I have even tried it on 2 different breadboards, as well as a prototyping board, with the same results. It is like the RTC chip is ignoring me.

Please can you check over my code, and see if anything obvious stands out. I have set the PIC18f2420 Oscconbits for the oscillator to run direct off the builtin 8mhz oscillator.

Thanking you all in advance ...

Code: [Select]

/*
 * File:   BigClock1.c
 * Author: Peter
 *
 * Created on 15 March 2015, 18:29
 */


// PIC18F2420 Configuration Bit Settings

// 'C' source line config statements

#include <p18F2420.h>

// CONFIG1H
#pragma config OSC = INTIO67    // Oscillator Selection bits (Internal oscillator block, port function on RA6 and RA7)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor disabled)
#pragma config IESO = OFF       // Internal/External Oscillator Switchover bit (Oscillator Switchover mode disabled)

// CONFIG2L
#pragma config PWRT = OFF       // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = OFF      // Brown-out Reset Enable bits (Brown-out Reset disabled in hardware and software)
#pragma config BORV = 3         // Brown Out Reset Voltage bits (Minimum setting)

// CONFIG2H
#pragma config WDT = OFF        // Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit))
#pragma config WDTPS = 32768    // Watchdog Timer Postscale Select bits (1:32768)

// CONFIG3H
#pragma config PBADEN = OFF     // PORTB A/D Enable bit (PORTB<4:0> pins are configured as digital I/O on Reset)
#pragma config LPT1OSC = OFF    // Low-Power Timer1 Oscillator Enable bit (Timer1 configured for higher power operation)
#pragma config MCLRE = ON       // MCLR Pin Enable bit (MCLR pin enabled; RE3 input pin disabled)

// CONFIG4L
#pragma config STVREN = ON      // Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset)
#pragma config LVP = ON         // Single-Supply ICSP Enable bit (Single-Supply ICSP enabled)
#pragma config XINST = OFF      // Extended Instruction Set Enable bit (Instruction set extension and Indexed Addressing mode disabled (Legacy mode))

// CONFIG5L
#pragma config CP0 = OFF        // Code Protection bit (Block 0 (000800-001FFFh) not code-protected)
#pragma config CP1 = OFF        // Code Protection bit (Block 1 (002000-003FFFh) not code-protected)

// CONFIG5H
#pragma config CPB = OFF        // Boot Block Code Protection bit (Boot block (000000-0007FFh) not code-protected)
#pragma config CPD = OFF        // Data EEPROM Code Protection bit (Data EEPROM not code-protected)

// CONFIG6L
#pragma config WRT0 = OFF       // Write Protection bit (Block 0 (000800-001FFFh) not write-protected)
#pragma config WRT1 = OFF       // Write Protection bit (Block 1 (002000-003FFFh) not write-protected)

// CONFIG6H
#pragma config WRTC = OFF       // Configuration Register Write Protection bit (Configuration registers (300000-3000FFh) not write-protected)
#pragma config WRTB = OFF       // Boot Block Write Protection bit (Boot block (000000-0007FFh) not write-protected)
#pragma config WRTD = OFF       // Data EEPROM Write Protection bit (Data EEPROM not write-protected)

// CONFIG7L
#pragma config EBTR0 = OFF      // Table Read Protection bit (Block 0 (000800-001FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR1 = OFF      // Table Read Protection bit (Block 1 (002000-003FFFh) not protected from table reads executed in other blocks)

// CONFIG7H
#pragma config EBTRB = OFF      // Boot Block Table Read Protection bit (Boot block (000000-0007FFh) not protected from table reads executed in other blocks)



#include <stdio.h>
#include <stdlib.h>
#include <p18f2420.h>
#include <timers.h>
#include <delays.h>
#include <i2c.h>
#include "xlcd.h"

void DelayFor18TCY( void )
{
Nop();Nop();Nop();Nop();Nop();Nop();
Nop();Nop();Nop();Nop();Nop();Nop();
}
void DelayPORXLCD (void)
{
Delay1KTCYx(60); // Delay of 15ms
return;
}
void DelayXLCD (void)
{
Delay1KTCYx(20); // Delay of 5ms
return;
}

void ds1307_write(unsigned char reg, unsigned char data)
{
       unsigned char stat;

       IdleI2C(); /* wait for an idle bus */
       StartI2C(); /* send START bit */
       while (SSPCON2bits.SEN); /* wait till START is sent */
       WriteI2C(0xd0); /* DS1377 WriteI2C address */
       AckI2C(); /* Slave ACK */
       WriteI2C(reg); /* Slave register address */
       AckI2C();
       WriteI2C(data); /* data */
       AckI2C();
       RestartI2C();
       while (SSPCON2bits.PEN); /* wait till STOP is sent */
}

void ds1307_read(unsigned char reg, unsigned char *data)
{
       unsigned char i;


       IdleI2C();
       StartI2C();
       while (SSPCON2bits.SEN);
       WriteI2C(0xd1);
       AckI2C();
       WriteI2C(0x00);
       AckI2C();

       StartI2C();
       while (SSPCON2bits.SEN);
       WriteI2C(0xd1);
       AckI2C();

       *data = ReadI2C();
       StopI2C();
       while (SSPCON2bits.PEN);
}

void ds1307_init(void)
{
            ds1307_write(0xE0, 0xFF); //SETTING BIT 7 (BAR EOSC) SHOULD TURNOFF
}


void main(void) {
    OSCCONbits.IRCF0=1; //8Mhz
    OSCCONbits.IRCF1=1;
    OSCCONbits.IRCF2=1;
       ADCON1 = 0x0f;
       LATA=0x00;
       LATB=0x00;
       LATC=0x00;
       TRISA = 0x00;
       TRISB = 0x00;
       TRISC = 0xFF; //Port C is in
       Delay10KTCYx(20);
        while( BusyXLCD() );
        OpenXLCD(  FOUR_BIT & LINES_5X7);
        WriteCmdXLCD( BLINK_OFF & CURSOR_OFF);
        WriteCmdXLCD( SHIFT_DISP_LEFT );

        putrsXLCD("DISPLAY IS ON");
     
       OpenI2C(MASTER, SLEW_OFF); /* I2C Master */
       SSPADD = 0x13; /* 100khz @ 8MHz */
       ds1307_init();
       while(1);
}


[dannyf]

The usual suspects:

1) make sure that your i2c modules are set up correct;
2) make sure that the slave address is right and consistent with your i2c routine's notation. For example, some routines use the 8-bit notion for slave address, 0b11010000, under such an approach, would be 0xd0; vs. 0x48 under the 7-bit notion.
3) I like the way you broke up the write/read functions but I am pretty sure that your read function has the incorrect timing. The typical approach to read from a given address is to first initiate a write approach to that address. Just before you actually write to that address - so you move the current data pointer to the desired address, you stop and restart the i2c transmission in read mode.
4) I don't know what AckI2C() does but masters typically don't acknowledge a transmission - it does Non-ack at the end of a transmission.
5) your code actually didn't attempt to change SQWE bit.

[kolbep]

Thanks for the reply.
I am using somebody else's routine, and they did have it working.
I will have to look into the i2c libraries to see how they have address formatted,,,

Originally I was trying to change the square wave output frequency, but then I thought I must just try to shut the rtc oscillator down, to check comms, which is on the unit function I set all the bits of 0x0e to 1, just because if the 7th bit is high, then it's oscillator should stop, which it wasnt .

I will check again tomorrow cos it is late here now, and I am replying on my cell...

[dannyf]

Here is what I have, working on realy ds1307:

Code: [Select]

//send byte to ch on ds1307
void ds1307_write(unsigned char ch, unsigned char byte_t) {
i2c_start(); //send the start condition
i2c_write(DS1307_I2C_ID | I2C_CMD_WRITE); //send the device id
i2c_write(ch); //send the channel
i2c_write(byte_t); //send the data
i2c_stop();
}

//read from ds1307
unsigned char ds1307_read(unsigned char ch) {
unsigned char dat;
i2c_start(); //start condition
i2c_write(DS1307_I2C_ID | I2C_CMD_WRITE); //second the id
i2c_write(ch); //send the channel
i2c_restart(); //restart
i2c_write(DS1307_I2C_ID | I2C_CMD_READ); //send the read command
dat=i2c_read(I2C_NOACK); //read from ds1307, no acknowledgement
i2c_stop();
return dat;
}
You may not have the same routines but it should give you a gist of what needs to be done.

[SL4P]

also, a general coding comment...
while (anything);
... is fine, but you should always consider the break condition may never occur...
adding a loop counter or other mechanism may save you from hard resets or some other construct to pull the program out of an infinite loop.
cheers

[Wilksey]

Do you have the pull-ups on the I2C lines?

[dannyf]

I put it through the simulator and here is what your code did.

So ds1307_init() sent the right i2c address (0xd0), and then wrote 0xbf to 0x70, when you wanted to send 0xff to 0xe0.

[dannyf]

I can confirm for you that commenting out the acki2c() in the write routine allowed the 0xff to be sent to 0xe0.

The original code is not correct.

[kolbep]

I do have pullups on there.
Thanks for the simulation of the code. What software did you use for that?
I will try later on (removing the ACK's) and see.

P

[kolbep]

Ok,
I got rid of their code (well, just did not call it).
What I did now in my main() was the following :

Code: [Select]

       OpenI2C(MASTER, SLEW_OFF); /* I2C Master */
       SSPADD = 0x13; /* 100khz @ 8MHz */
       StartI2C();
       while (SSPCON2bits.SEN);
       IdleI2C();
       WriteI2C(0xd0);
       IdleI2C();
       WriteI2C(0x0E);
       IdleI2C();
       WriteI2C(0xFF);
       StopI2C();
       while (SSPCON2bits.PEN);

And that worked. I thought I would never be so happy at watching my scope trace dissapear. For a second there, I actually checked my scope leads to make sure they were still in place.

If I change the output to that register to 0x00, now it is flashing the LED at 1HZ! Hooray.

Now to start asking the RTC Questions..

P

[kolbep]

and here is a pic of the Work in progress...