How to Use Timer-1 in AT89C1051 (8-bit Auto-Reload Mode)

The following code demonstrate, how to generate clock of 2.5Khz using timer-1 in auto reload mode. Every 200 micro-second timer-1 overflow flag goes high and  port P3.0 is inverted. The code is written in Keil uVision2 IDE and simulation is done with Proteus 8.0. At the end of code, you can find complete project files for download.

Code Using Keil uVision2

#include
#include
// proto-types
void ConfigTimer1(void);
void MonitorTimer1OverflowFlag(void);
void Delayms(unsigned int x_time);
// pin labling
sbit PULSE = P3^0;
sbit LED = P1^0;

void main(void)
{
// make pins as output
PULSE = 0;
LED = 0;
// config timer-1
ConfigTimer1();
while(1)
{
PULSE = ~PULSE;
MonitorTimer1OverflowFlag();
}
}
void ConfigTimer1(void)
{
// master clock is 12MHz
// timer clock is 1/12th => 1MHz
// in 8-bit mode timer overflow
// after 256 usec.
// for overflow every 200 usec
// 256-200 = 6 (0x06)
TH1 = 0x06;
// set timer-1 mode-2 (8-bit auto-reload)
TMOD = 0x20;
// start timer-1
TR1 = 1;
}
void MonitorTimer1OverflowFlag(void)
{
// monitor timer-1 overflow flag
while(TF1 == 0);
// reset overflow flag
TF1 = 0;
}
void Delayms(unsigned int x_time)
{
unsigned int x,y;
for(x=0;x<x_time;x++)
for(y=0;y<122;y++);
}

Download Files

For download Keil project and Proteus 8.0 simulation files, click here.