8051 Micro controller
Upon reset all port pins and port registers are high. I follow these instructions...
P0=0x00; P0=0xFF;
Now ,the result is - All P0 registers are high & all P0 pins are low.
Q1) Does this low P0 pins indicate high impedance floating load in the case of P0?
Now, I start the program with the following instruction only.
P0=0xFF;
But All P0 registers and pins remain high.
Q2)What is the difference here? What's happening inside circuitry in both cases?
anyhow: why do you give a hoot what the simulator shows, what does your actual circuit do?
a simulator is, by definition, imperfect especially when trying to cover the 4711 variants of the .51
I was trying to interface active high switch to port 0. Since only P0 have the open drain I/O pin in the case of 8051.
No, that's not true - all 8051 IO pins are open-drain!