Hello guys,

I am presently working on the Holtek serial Timer IC and interfacing it with the AT89C51. I have the circuit hardware. the problem is that there is no reply form the timer IC.

What i am doing is that i have connected the MCU to the serial port of the computer. when i switch it on the MCU is suppose to initialize the 1380 and then whatever command i give to the MCU(0x81,0x83,0x85 ie the read addresses of the registers), I should get the data stored on that register serially to my com port.

But the problem is that i either get 0x7F or 0x40 on my computer serial port as a reply.

I have changed the 32768Hz crystal and the capacitors many times.

The link to the datasheet is:
http://www.holtek.com/pdf/consumer/1380_1v111.pdf

I am insetting the program code as well.

I have two extra LED's connected to the P3_6 and P3_7 of the MCU just for the sake of indication and troubleshooting.

************************************************************************************

#include "8051.h"
#include "serial.h"

#define SCLK P2_0
#define DATA_IO P2_1
#define RESET_ P2_2
#define YELLOW_LED P3_6
#define RED_LED P3_7

unsigned char serial_storage=0x00;
unsigned char display;

void usec_wait(unsigned char);
void msec_wait(unsigned char);
void sec_wait(unsigned char);
void convert_and_send(unsigned char);
unsigned char receive_convert(void);


//**************************************************************
//DELAY FUNCTIONS - USEC_WAIT ; MSEC_WAIT ; SEC_WAIT
//**************************************************************
void usec_wait(unsigned char k)
{
while(k!=0)
{
k--;
}
}
//////////////////////////////////////////////////////
void msec_wait(unsigned char j)
{
while(j!=0)
{
usec_wait(165);
j--;
}
}
//////////////////////////////////////////////////////
void sec_wait(unsigned char sec_count)
{
while(sec_count!=0)
{
msec_wait(250);
msec_wait(250);
msec_wait(250);
msec_wait(250);
sec_count--;
}
}
//////////////////////////////////////////////////////

//**************************************************************
//SERIAL INTERRUPT FUNCTION
//**************************************************************

void serial_interrupt() interrupt 4
{
if(TI)
TI=0;

if(RI)
{
serial_storage=SBUF;
usec_wait(1);
RI=0;
RED_LED=1;
}
}


//********************************************************************************
//FUNCTION THAT SENDS ADDRESS OR DATA_IO AFTER CONVERTING IT TO BITS TO THE 1380
//********************************************************************************
void convert_and_send(unsigned char hex_data1)
{
bit sending_bit;
unsigned char comparing_byte=0x01,i,storing_byte=0x00;
SBUF=hex_data1;
msec_wait(10);
for(i=0;i<8;i++)
{
SCLK=0;
storing_byte=(hex_data1&comparing_byte);
if(storing_byte==0x00)
{
sending_bit=0;
}
else
{
sending_bit=1;
}
//send bit

DATA_IO = sending_bit; //Clock to DATA_IO delay is 250ns (max)
comparing_byte=comparing_byte<<1;
SCLK=1; //this is kept here to save the time in giving dalay after DATA_IO sent, instead in that time calculations are done
}
serial_storage=0x00;
usec_wait(2);
}


//*************************************************************************************************
//FUNCTION THAT RECEIVES DATA FROM 1380 AND THEN CONVERTS IT TO CHARACTER AND PASSES TO ITS CALLER
//*************************************************************************************************
unsigned char receive_convert(void)
{
unsigned char comparing_byte=0x00,received_data=0x00,i=0;
bit receiving_bit;
YELLOW_LED=0;
sec_wait(2);
YELLOW_LED=1;
sec_wait(1);
for(i=0;i<8;i++)
{
DATA_IO=1;
SCLK=1;

SCLK=0;
usec_wait(1);
receiving_bit=DATA_IO;
if(receiving_bit==0)
{
comparing_byte=0x00;
}
else
{
comparing_byte=0x80; //comparing byte is 10000000 as the bit is to be placesd in the MSB position
}
received_data = received_data|comparing_byte;
received_data = received_data>>1;
}
return(received_data);
}


void main()
{

initialize_serial(); //INITIALIZES THE SERIAL PORT

RED_LED=0; //BOTH LED's GLOW WHEN THE RTC IS BEING SET
YELLOW_LED=0;

RESET_=1;
msec_wait(2);
convert_and_send(0x8E); //SETS THE WP BIT AS ZERO
msec_wait(1);
convert_and_send(0x00);
RESET_=0;
msec_wait(2);

RESET_=1;
msec_wait(2);
convert_and_send(0x80); //SETS THE CH BIT AS ZERO
msec_wait(1);
convert_and_send(0x00);
usec_wait(1);
RESET_=0;

RED_LED=1;
sec_wait(4); //waiting time given so that oscilator can start up to speed and gets ready to recieve time
RED_LED=0;

RESET_=1;
msec_wait(2);
convert_and_send(0x80); //10000000,00010000-sec:10
msec_wait(1);
convert_and_send(0x10);
RESET_=0;
usec_wait(1);

RESET_=1;
msec_wait(2);
convert_and_send(0x82); //10000010,00010000-min:10
msec_wait(1);
convert_and_send(0x10);
RESET_=0;
usec_wait(1);

RESET_=1;
msec_wait(2);
convert_and_send(0x84); //10000100,00010000-hour:10,24hr mode
msec_wait(1);
convert_and_send(0x10);
RESET_=0;
usec_wait(1);

RESET_=1;
msec_wait(2);
convert_and_send(0x86); //10000110,00010000-date:10
msec_wait(1);
convert_and_send(0x10);
RESET_=0;
usec_wait(1);

RESET_=1;
msec_wait(2);
convert_and_send(0x88); //10001000,00010000-month:05
msec_wait(1);
convert_and_send(0x05);
RESET_=0;
usec_wait(1);

RESET_=1;
msec_wait(2);
convert_and_send(0x8A); //10001010,00010000-day of week:friday ie 7
msec_wait(1);
convert_and_send(0x07);
RESET_=0;
usec_wait(1);

RESET_=1;
msec_wait(2);
convert_and_send(0x8C); //10001100,00001000-year:08
msec_wait(1);
convert_and_send(0x08);
RESET_=0;
usec_wait(1);

RESET_=1;
msec_wait(2);
convert_and_send(0x8E); //SETS THE WP BIT AS ONE PREVENT DATA_IO FROM BEING WRITTEN ONTO THE REGISTERS
msec_wait(1);
convert_and_send(0x80);
RESET_=0;


RED_LED=1; //BOTH LED's TURN OFF WHEN THE RTC TIME HAS BEEN SET
YELLOW_LED=1;

while(1) //INFINITE LOOP
{
RED_LED=0; //This shows that only the while loop is running and system is waiting for command(REGISTER ADDRESS)
msec_wait(500);
if(serial_storage!=0x00)
{
SCLK = 0;
RED_LED=1; //This shows that the serial_storage has the character
RESET_=1;
convert_and_send(serial_storage); //sending the address of the register that we want to read from
msec_wait(10);
display=receive_convert(); //putting the read DATA_IO into display
RESET_=0;
SBUF=display; //sending the read DATA_IO serially to the computer
msec_wait(2);
display=0x00;
}
else
{
RED_LED=1;
msec_wait(500);
}
}

}