[SOLVED] [Moved] MICROCONTROLLER - PORT 0 is not giving output high voltage

[knark]

i am burning this program in the controller 89c51 and o am setting all the pins of port 0 equals to 1 and the high voltage at port 0 is not ore than 0.7V while it gives 0V at low my code is

#include<reg52.h>
#define port P1
#define key P0


void main()
{
key=0xFF;
}
please if any one can help me out

 

[Qaisar Azeemi]

PORT 0 of 89c51 and 89c52 are open collector outputs. means you have to connect a pull up resistor with p0 of 89c51/89c52. without pull up resistor it will not work. so put a pull up resistor of any value, 1k ohm , 2.2k ohms or 3.9k ohms with this port and then connect the load with it.

look at a simple schemetic just for understanding.



regards