microcontroller 8051

Take the full marking of MCU.

May be useful: http://www.pjrc.com/tech/8051/board5/timers.html

Hi,

I am using a microcontroller 8051. I need an embedded C program for a time delay of 1-hour (ON state) and 1-hour (OFF state). The relay is continuous. Also, how do I interface that relay and the microcontroller?

Thanks!

A program would be a piece of cake (pie?) and it would likely even run, but I'd need to know more:
What's the crystal frequency?
Do you have a timing source other than the crystal, such as AC (limited to Vcc of course)?
Do you have a specific output?
Is this enabled with an input? Which input?

As for driving a relay, i'd need more information as well:
Do you have a power source other than the cpu power? If not there could be noise problems. What's the voltage and current capability of the supply.?
What's the relay coil voltage and current?

I use an old dumb as dirt assembler. I could give you source as a text file.
If you need it in C or some other programming language you're on your own.

Most importantly, if this is a school project why aren't you doing it yourself?

If you not yet to found the solution just try to using the 555 timer. it easier.



Good luck.

sorry, I misread your email and just noticed you needed a c program. I don't have an 8051 C compiler so I can't help with the program.

As to the 555, it's a completely different solution. It would work if the timing is approximate but if you need accurate timing a 555 won't work. The crystal timing in a microprocessor would be much better, but a diode, resistor and optoisolator would produce a square wave from AC, even 120VAC, which could be counted for perfectly accurate timing.

*
Download MikroC for 8051, here's a piece of code for your purpose
void main()
{
P1=0x00; //Initialise Port 1 as output
while(1)
{
P1=0xFF; //connect any pin of Port1 to relay usi a transistor
delay_ms(3600000);//36000000 milliseconds =1 Hour
P1=0x00; //Relay off after an hour
delay_ms(3600000);
}
} //end of program

Hope it helps!
Cheers!

One person got the right answer "Easy when you know how ! " Onnly one slight addition to this make suse you use an opto coupler , and put a 5v1 zenor on the port pin so as to ensure overvoltage protection if your not using opto couplers

You need a simple program i found it on the link http://microcontroler.weebly.com/displaying-text-on-16x2-lcd.html
now if you want to check time display than go a head made circuit and check it . I think it might help you