Hi Sr,

the AT89S52 is a very nice micro, usually running without any problems.

Try to use two 27pF or 33pF caps at the oscillator, though.

The connections of oscillator must be kept extremely short, like shown in this example:




Micros in this huge DIL40 package cannot have their power supply voltage easily be decoupled. In a bread board design this can be a problem. Usually, a solid ground plane is used, to keep the inductance and resistance of digital ground low and by this minimize the ground and supply ripple. Look at this example:




The AT89S52 is a micro with a flash code memory. Use the micro only in combination with a proper reset controller, like shown in another example:




Is this the whole program? What do you expect from it to do?


Kai Klaas