[SOLVED] Help with RTC(PCF8583) using PIC18F4550

[mariuszoll]

Hi,

I am working on a calendar/clock application that uses PCF8583 RTC and PIC18F4550. The pull-up resistors on SCL and SDA are both of 4k7. I use serial communication (USART) and Hyperterminal to display the information. I display the date on dd/mm/yy format and the time on hh/mm/ss format. It does not work properly as expected. It displays:

Date: 45/25/12
Time: 45:165:1
.............
45:165:59

As far the seconds are concerned, they are incrementing correctly from 1 to 59.

Could you help me please to fix this problem?

Attached you can find my code:

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Code C - [expand]
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#include <p18f4550.h>
#include <delays.h>
#include <sw_uart.h>
#include <i2c.h>
 
// Pragma, internal register configuration
 
#pragma config FOSC = INTOSCIO_EC //Internal oscillator, port function on RA6, EC used by USB 
#pragma config WDT = OFF // watch dog disabled
#pragma config IESO = OFF //Oscillator Switchover mode disabled 
//#pragma config PWRT = OFF //PWRT disabled 
#pragma config BORV = 2 // output voltage test 2V
#pragma config PBADEN=OFF //PORTB<4:0> pins are configured as digital I/O on Reset 
#pragma config STVREN=OFF //Stack full/underflow will not cause Reset 
#pragma config LVP=OFF //Single-Supply ICSP disabled 
#pragma config XINST=OFF //Instruction set extension and Indexed Addressing mode disabled (Legacy mode)
 
 
// definitions
 
#define PCF8583_WRITE_ADDRESS 0xA0 
#define PCF8583_READ_ADDRESS 0xA1 
 
// Register addresses 
#define PCF8583_CTRL_STATUS_REG 0x00 
#define PCF8583_100S_REG 0x01 
#define PCF8583_SECONDS_REG 0x02 
#define PCF8583_MINUTES_REG 0x03 
#define PCF8583_HOURS_REG 0x04 
#define PCF8583_DATE_REG 0x05 
#define PCF8583_MONTHS_REG 0x06 
#define PCF8583_TIMER_REG 0x07 
 
#define PCF8583_ALARM_CONTROL_REG 0x08 
#define PCF8583_ALARM_100S_REG 0x09 
#define PCF8583_ALARM_SECS_REG 0x0A 
#define PCF8583_ALARM_MINS_REG 0x0B 
#define PCF8583_ALARM_HOURS_REG 0x0C 
#define PCF8583_ALARM_DATE_REG 0x0D 
#define PCF8583_ALARM_MONTHS_REG 0x0E 
#define PCF8583_ALARM_TIMER_REG 0x0F 
 
// Use the first NVRAM address for the year byte. 
#define PCF8583_YEAR_REG 0x10 
 
 
// Commands for the Control/Status register. 
#define PCF8583_START_COUNTING 0x00 
#define PCF8583_STOP_COUNTING 0x80 
 
// Structure defines the user's date and time data.
typedef struct{
unsigned char seconds; // 0 to 59
unsigned char minutes; // 0 to 59
unsigned char hours; // 0 to 23
unsigned char day; // 1 to 31
unsigned char month; // 1 to 12
unsigned char year; // 0 to 99
unsigned char weekday; // 0=Sunday, 1=Monday, etc
} date_time_t;
 
// Variables
 
/** L O C A L F U N C T I O N S *******************************************/
 
void init_UART(void)
{
TXSTAbits.TX9=0;
TXSTAbits.TXEN=1;
TXSTAbits.SYNC=0;
TXSTAbits.BRGH=1;
TXSTAbits.TX9D=0;
RCSTAbits.SPEN=1;
BAUDCONbits.BRG16=0;
SPBRG=25; // 9600KBaud
}
 
void PCF8583_write_byte(char address, char data)
{
IdleI2C();
StartI2C(); //start
while(SSPCON2bits.SEN);
Delay1TCY(); // delay 5us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY(); 
 
WriteI2C(PCF8583_WRITE_ADDRESS); // address and write flag
IdleI2C();
WriteI2C(address);
IdleI2C();
WriteI2C(data);
IdleI2C();
StopI2C();
while(SSPCON2bits.PEN); // stop
Delay1TCY(); // delay 4us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY();
} 
 
char PCF8583_read_byte(char address)
{
char retval;
 
IdleI2C();
StartI2C(); //start
while(SSPCON2bits.SEN);
 
Delay1TCY(); // delay 5us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY(); 
 
WriteI2C(PCF8583_WRITE_ADDRESS); // address and write flag
IdleI2C();
WriteI2C(address);
IdleI2C();
 
RestartI2C(); //restart
while(SSPCON2bits.RSEN);
 
Delay1TCY(); // delay 5us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY(); 
 
WriteI2C(PCF8583_READ_ADDRESS); //address and read flag
IdleI2C();
retval=ReadI2C();
IdleI2C();
 
StopI2C();
while(SSPCON2bits.PEN); // stop
Delay1TCY(); // delay 4us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY();
 
return(retval);
}
 
void PCF8583_init(void)
{
PCF8583_write_byte(PCF8583_CTRL_STATUS_REG,PCF8583 _START_COUNTING);
}
 
// This function converts an 8 bit binary value 
// to an 8 bit BCD value. 
// The input range must be from 0 to 99
 
unsigned char bin2bcd(unsigned char x)
{
unsigned char y;
 
y=(x / 10) << 4;
y= y | (x % 10);
return(y);
} 
 
// This function converts an 8 bit BCD value to 
// an 8 bit binary value. 
// The input range must be from 00 to 99. 
 
unsigned char bcd2bin(unsigned char x)
{ 
unsigned char binary;
binary = ((x & 0xF0 )>>4 ) * 10 + (x & 0x0F);
return (binary);
} 
 
void PCF8583_set_datetime( date_time_t *dt)
{
unsigned char bcd_sec;
unsigned char bcd_min;
unsigned char bcd_hrs;
unsigned char bcd_day;
unsigned char bcd_mon;
 
// Convert the input date/time into BCD values
// that are formatted for the PCF8583 registers
bcd_sec=bin2bcd(dt->seconds);
bcd_min=bin2bcd(dt->minutes);
bcd_hrs=bin2bcd(dt->hours);
bcd_day=bin2bcd(dt->day) | (dt->year <<6);
bcd_mon=bin2bcd(dt->month) |(dt->weekday << 5); 
 
// Stop the RTC from counting, before we write to the date and time registers
PCF8583_write_byte(PCF8583_CTRL_STATUS_REG,PCF8583 _STOP_COUNTING);
 
// Write to the date and time registers
IdleI2C();
StartI2C(); //start
while(SSPCON2bits.SEN);
Delay1TCY(); // delay 5us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY(); 
 
WriteI2C(PCF8583_WRITE_ADDRESS); // address and write flag
IdleI2C();
WriteI2C(PCF8583_100S_REG); // Start at 100's reg
IdleI2C();
WriteI2C(0x00); // Set 100's reg=0
IdleI2C();
WriteI2C(bcd_sec);
IdleI2C();
WriteI2C(bcd_min);
IdleI2C();
WriteI2C(bcd_hrs);
IdleI2C();
WriteI2C(bcd_day);
IdleI2C();
WriteI2C(bcd_mon);
IdleI2C();
 
StopI2C();
while(SSPCON2bits.PEN); // stop
Delay1TCY(); // delay 4us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY();
 
// Write the year to the first NVRAM location. Live it in binary format.
PCF8583_write_byte(PCF8583_YEAR_REG,dt->year);
 
// Now allow the RTC to start counting again
PCF8583_write_byte(PCF8583_CTRL_STATUS_REG,PCF8583 _START_COUNTING);
}
 
 
//Read the Date and Time from the hardware registers in the PCF8583
void PCF8583_read_datetime(date_time_t *dt)
{
unsigned char year_bits;
unsigned char year;
 
unsigned char bcd_sec;
unsigned char bcd_min;
unsigned char bcd_hrs;
unsigned char bcd_day;
unsigned char bcd_mon;
 
// Read the date/time registers inside the PCF8583
IdleI2C();
StartI2C(); //start
while(SSPCON2bits.SEN);
Delay1TCY(); // delay 5us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY(); 
 
WriteI2C(PCF8583_WRITE_ADDRESS); // address and write flag
IdleI2C();
WriteI2C(PCF8583_SECONDS_REG); // Start at secods reg
IdleI2C();
 
RestartI2C(); //start
while(SSPCON2bits.RSEN);
Delay1TCY(); // delay 5us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY(); 
WriteI2C(PCF8583_READ_ADDRESS); // address and write flag
IdleI2C();
 
bcd_sec=ReadI2C();
IdleI2C();
bcd_min=ReadI2C();
IdleI2C();
bcd_hrs=ReadI2C();
IdleI2C();
bcd_day=ReadI2C();
IdleI2C();
bcd_mon=ReadI2C();
IdleI2C();
 
StopI2C();
while(SSPCON2bits.PEN); // stop
Delay1TCY(); // delay 4us (see datasheet pg20)
Delay1TCY();
Delay1TCY();
Delay1TCY();
 
// Convert the date/time values from BCD to 
// unsigned 8-bit integers. Unpack the bits 
// in the PCF8583 registers where required. 
dt->seconds = bcd2bin(bcd_sec); 
dt->minutes = bcd2bin(bcd_min); 
dt->hours = bcd2bin(bcd_hrs & 0x3F); 
dt->day = bcd2bin(bcd_day & 0x3F); 
dt->month = bcd2bin(bcd_mon & 0x1F); 
dt->weekday=bcd_mon >> 5;
year_bits=bcd_day >> 6 ;
 
// Read the year byte from NVRAM. 
// This is an added feature of this driver. 
year = PCF8583_read_byte(PCF8583_YEAR_REG); 
 
/* //Check if the two " year bits " were incremented by the PCF8583.
while(year_bits!= (year & 3)) year++;
 
dt->year=year;
 
// Now update the year byte in the NVRAM inside the PCF8583
PCF8583_write_byte(PCF8583_YEAR_REG, year); */
 
}
 
void print_date_time(char t)
{
int k,n,j,m,c;
unsigned char data;
char string[5];
 
data=t;
n=data;
j=0;
 
while(n!=0)
{
c=n%10;
n=n/10;
string[j]=c+48;
j++;
}
 
m=j-1;
 
while(m>=0)
{
WriteUSART(string[m]);
while(!TXSTAbits.TRMT);
m--;
}
} 
 
///////////////////functia main///////////////////////////////////////////
 
void main(void)
{
 
date_time_t dt;
 
//Outputs:
 
TRISCbits.TRISC6=0; // UART__TX
 
//Inputs:
 
TRISBbits.TRISB0=1; // I2C_SDA
TRISBbits.TRISB1=1; // I2C_SCL
TRISCbits.TRISC7=1; // UART__RX
 
// Oscillator frequency
 
OSCCON=0b01100110; // 4MHz
 
// the configuration of the functions of port pins
 
ADCON1=0b00001111; // digital port configured
 
// Initializations
 
init_UART();
TXREG=12; // new page
 
// I2C settings
 
SSPSTAT=0x80; // SLEW RATE CONTROL DISABLED FOR std mode (100khz)
SSPCON1=0x28; // i2c master mode, serial synch enable
SSPCON2=0x00;
SSPADD=0x09; // for 100Khz
 
PCF8583_init();
 
dt.seconds=0; // 0 seconds
dt.minutes=25; // 25 minutes
dt.hours=10; // 10am - 24-hour format
dt.day=27; // 27
dt.month=8; // August
dt.weekday=1; // Monday
dt.year=12; // 2012
 
PCF8583_set_datetime(&dt);
 
while(1) 
{ 
// Read the date and time from the PCF8583 and dispaly it once per second
Delay10KTCYx(100);
 
PCF8583_read_datetime(&dt); 
 
print_date_time(dt.weekday);
TXREG=32; // space
TXREG=32; // space
print_date_time(dt.day);
TXREG=47; // /
print_date_time(dt.month);
TXREG=47;
print_date_time(dt.year);
TXREG=32; // space
TXREG=32; // space
 
print_date_time(dt.hours);
TXREG=58; // :
print_date_time(dt.minutes);
TXREG=58;
print_date_time(dt.seconds);
TXREG=10; // new line
TXREG=13; //carriage return
 
}
} // main

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Thank you in advance.

 

[mariuszoll]

Hi,

I succedded to make it to work. For they who are interested to find out how to program PIC18F4550 in order to read the date and time from PCF8583 and to display it on Hyperterminal using the serial comunication RS232 the code is below:

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Code C - [expand]
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//Program
 
#include <p18f4550.h>
#include <delays.h>
#include <sw_uart.h>
#include <i2c.h>
 
// Pragma, internal register configuration
 
#pragma config FOSC = INTOSCIO_EC   //Internal oscillator, port function on RA6, EC used by USB 
#pragma config WDT = OFF            // watch dog disabled
#pragma config IESO = OFF           //Oscillator Switchover mode disabled 
//#pragma config PWRT = OFF             //PWRT disabled     
#pragma config BORV = 2             // output voltage test 2V
#pragma config PBADEN=OFF           //PORTB<4:0> pins are configured as digital I/O on Reset 
#pragma config STVREN=OFF           //Stack full/underflow will not cause Reset 
#pragma config LVP=OFF              //Single-Supply ICSP disabled 
#pragma config XINST=OFF            //Instruction set extension and Indexed Addressing mode disabled (Legacy mode)
 
 
// definitions
 
#define PCF8583_WRITE_ADDRESS 0xA0 
#define PCF8583_READ_ADDRESS  0xA1 
 
// Register addresses 
#define PCF8583_CTRL_STATUS_REG    0x00 
#define PCF8583_100S_REG           0x01 
#define PCF8583_SECONDS_REG        0x02 
#define PCF8583_MINUTES_REG        0x03 
#define PCF8583_HOURS_REG          0x04 
#define PCF8583_DATE_REG           0x05 
#define PCF8583_MONTHS_REG         0x06 
#define PCF8583_TIMER_REG          0x07 
 
#define PCF8583_ALARM_CONTROL_REG  0x08 
#define PCF8583_ALARM_100S_REG     0x09 
#define PCF8583_ALARM_SECS_REG     0x0A 
#define PCF8583_ALARM_MINS_REG     0x0B 
#define PCF8583_ALARM_HOURS_REG    0x0C 
#define PCF8583_ALARM_DATE_REG     0x0D 
#define PCF8583_ALARM_MONTHS_REG   0x0E 
#define PCF8583_ALARM_TIMER_REG    0x0F 
 
// Use the first NVRAM address for the year byte. 
#define PCF8583_YEAR_REG           0x10 
 
 
// Commands for the Control/Status register. 
#define PCF8583_START_COUNTING     0x00 
#define PCF8583_STOP_COUNTING      0x80 
 
// Variables
unsigned char seconds=0x00,minutes=0x00,hours=0x00,day=0x00,month=0x00,year=0x00;
 
/** L O C A L   F U N C T I O N S  *******************************************/
 
void init_UART(void)
{
    TXSTAbits.TX9=0;
    TXSTAbits.TXEN=1;
    TXSTAbits.SYNC=0;
    TXSTAbits.BRGH=1;
    TXSTAbits.TX9D=0;
    RCSTAbits.SPEN=1;
    BAUDCONbits.BRG16=0;
    SPBRG=25;           // 9600KBaud
}
 
// Read time and date information from RTC( PCF8583 )
void Read_Time(void)
{
    // read seconds
    StartI2C();
    while(SSPCON2bits.SEN);
    WriteI2C(PCF8583_WRITE_ADDRESS);    // Address and Write Flag
    WriteI2C(PCF8583_SECONDS_REG);      // Start from seconds memory location
    RestartI2C();                       // At this moment master transmitter becomes master receiver 
    while(SSPCON2bits.RSEN);            // and PCF8583 slave receiver becomes slave transmitter
    WriteI2C(PCF8583_READ_ADDRESS);     // Address and Read Flag
    seconds=ReadI2C();                  // read seconds reg
    NotAckI2C();
    StopI2C();
    while(SSPCON2bits.PEN);
 
    // read minutes
    StartI2C();
    while(SSPCON2bits.SEN);
    WriteI2C(PCF8583_WRITE_ADDRESS);    // Address and Write Flag
    WriteI2C(PCF8583_MINUTES_REG);      // Start from minutes memory location
    RestartI2C();                       // At this moment master transmitter becomes master receiver 
    while(SSPCON2bits.RSEN);            // and PCF8583 slave receiver becomes slave transmitter
    WriteI2C(PCF8583_READ_ADDRESS);     // Address and Read Flag
    minutes=ReadI2C();                  // read minutes reg
    NotAckI2C();
    StopI2C();
    while(SSPCON2bits.PEN);
 
    // read hours
    StartI2C();
    while(SSPCON2bits.SEN);
    WriteI2C(PCF8583_WRITE_ADDRESS);    // Address and Write Flag
    WriteI2C(PCF8583_HOURS_REG);        // Start from hours memory location
    RestartI2C();                       // At this moment master transmitter becomes master receiver 
    while(SSPCON2bits.RSEN);            // and PCF8583 slave receiver becomes slave transmitter
    WriteI2C(PCF8583_READ_ADDRESS);     // Address and Read Flag
    hours=ReadI2C();                    // read hours reg
    NotAckI2C();
    StopI2C();
    while(SSPCON2bits.PEN);
 
    // read day
    StartI2C();
    while(SSPCON2bits.SEN);
    WriteI2C(PCF8583_WRITE_ADDRESS);    // Address and Write Flag
    WriteI2C(PCF8583_DATE_REG);         // Start from year/date memory location
    RestartI2C();                       // At this moment master transmitter becomes master receiver 
    while(SSPCON2bits.RSEN);            // and PCF8583 slave receiver becomes slave transmitter
    WriteI2C(PCF8583_READ_ADDRESS);     // Address and Read Flag
    day=ReadI2C();                      // read year/date reg
    NotAckI2C();
    StopI2C();
    while(SSPCON2bits.PEN);
 
    // read month
    StartI2C();
    while(SSPCON2bits.SEN);
    WriteI2C(PCF8583_WRITE_ADDRESS);    // Address and Write Flag
    WriteI2C(PCF8583_MONTHS_REG);       // Start from weekday/month memory location
    RestartI2C();                       // At this moment master transmitter becomes master receiver 
    while(SSPCON2bits.RSEN);            // and PCF8583 slave receiver becomes slave transmitter
    WriteI2C(PCF8583_READ_ADDRESS);     // Address and Read Flag
    month=ReadI2C();                    // read weekday/month reg
    NotAckI2C();
    StopI2C();
    while(SSPCON2bits.PEN);
 
}
 
//  Formats date and time
void Transform_Time() 
{
    seconds  =  ((seconds & 0xF0) >> 4)*10 + (seconds & 0x0F);              // Transform seconds
    minutes  =  ((minutes & 0xF0) >> 4)*10 + (minutes & 0x0F);              // Transform months
    hours    =  (((hours & 0xF0)  >> 4)*10  + (hours & 0x0F)) & 0x3F;       // Transform hours
//  year     =   (day & 0xC0) >> 6;                                         // Transform year
    day      =  (((day & 0x30) >> 4)*10    + (day & 0x0F)) & 0x3F;          // Transform day
    month    =  (((month & 0x10)  >> 4)*10 + (month & 0x0F)) & 0x3F;        // Transform month
}
 
// This function converts an 8 bit binary value 
// to an 8 bit BCD value. 
// The input range must be from 0 to 99
 
unsigned char bin2bcd(unsigned x)
{
    unsigned char y;
 
    y=(x / 10) << 4;
    y= y | (x % 10);
    return(y);
} 
 
// This function converts an 8 bit BCD value to 
// an 8 bit binary value. 
// The input range must be from 00 to 99. 
 
unsigned bcd2bin(unsigned char x)
{ 
 
return (x & 0x0F) + (x >> 4)*10;
 
} 
 
void print_date_time(char t)
    {
        int k,n,j,m,c;
        unsigned char data;
        unsigned char string[5];
 
        data=t;
        n=data;
        j=0;
 
        while(n!=0)
        {
            c=n%10;
            n=n/10;
            string[j]=c+48;
            j++;
        }
            
        m=j-1;
            
        while(m>=0)
        {
            WriteUSART(string[m]);
            while(!TXSTAbits.TRMT);
            m--;
        }
    }   
 
///////////////////functia main///////////////////////////////////////////
 
void main(void)
 {
    
        //Outputs:
 
        TRISCbits.TRISC6=0;     // UART__TX
        
        //Inputs:
 
        TRISBbits.TRISB0=1;     // I2C_SDA
        TRISBbits.TRISB1=1;     // I2C_SCL
        TRISCbits.TRISC7=1;     // UART__RX
 
        // Oscillator frequency
    
        OSCCON=0b01100110;      // 4MHz
        
        // the configuration of the functions of port pins
        
        ADCON1=0b00001111;      // digital port configured
    
        // Initializations
 
        init_UART();
        TXREG=12;               // new page
 
        // I2C settings
 
        SSPSTAT=0x80;   // SLEW RATE CONTROL DISABLED FOR std mode (100khz)
        SSPCON1=0x28;   // i2c master mode, serial synch enable
        SSPCON2=0x00;
        SSPADD=0x09;    // for 100Khz
        
        // Set time and date
 
        StartI2C();
        while(SSPCON2bits.SEN);
        WriteI2C(PCF8583_WRITE_ADDRESS);    // Address and Write Flag
        WriteI2C(PCF8583_CTRL_STATUS_REG);  // start from address 0 (control/status reg)
        WriteI2C(PCF8583_STOP_COUNTING);    // write 0x80 to control/status reg (stop counting)
        WriteI2C(0x00);                     // write 0 to 100's memory location
        WriteI2C(0x00);                     // write 0 to seconds memory location
        WriteI2C(0x52);                     // write 0x18 to minutes memory location        
        WriteI2C(0x15);                     // write 0x09 to hours memory location
        WriteI2C(0x30);                     // write 0x18 to year/date memory location      
        WriteI2C(0x08);                     // write 0x09 to weekday/month memory location
        StopI2C();
        while(SSPCON2bits.PEN);
 
        StartI2C();
        while(SSPCON2bits.SEN);
        WriteI2C(PCF8583_WRITE_ADDRESS);    // Address and Write Flag
        WriteI2C(PCF8583_CTRL_STATUS_REG);  // Start from address 0
        WriteI2C(PCF8583_START_COUNTING);   // write 0x00 to control/status reg (enable counting)
        StopI2C();
        while(SSPCON2bits.PEN);
 
    while(1) 
        {   
            // Read the date and time from the PCF8583 and dispaly it once per second
            Delay10KTCYx(100);
 
            Read_Time();
            Transform_Time();
    
            print_date_time(hours);
            TXREG=58;           // :
            print_date_time(minutes);
            TXREG=58;           // :
            print_date_time(seconds);
            TXREG=32;           // space
            TXREG=32;           //space
            print_date_time(day);
            TXREG=47;           // /
            print_date_time(month);
            TXREG=10;           // new line
            TXREG=13;           //carriage return  
 
        }
}  // main

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