I am using 89C51ED2, my code is executing fine but the P3^7 does not set high on reset and even I kept it high in code. Why is this occuring?
I've defined the port P3^7 as: sbit DEV_SEL P3^7, whereas DEV_SEL is been used to multiplex the communication path for serial comm. using 4052 IC. Rest of my code is working fine with the Hardware but the pin P3^7 is not changing the state, it always remains cleared. I am using Keil Compiler version 7.07a. Whole code is simulating well. The simulator shows the change in state of P3^7 but the Hardware does not. I do think that 89C51ED2 would require any value in some specified Register which I don't know. Please Help me ASAP.
4 possibilities 1) it get set low "somewhwre" 2) it is shorted to ground 3) the chip is bad 4) whatever is connected to it hold it low
Erik
maybe:
5) It relies upon an external pull-up, and that happens to be faulty?
can thje ED2 ports be configured?
I had removed the chip 4052 which is connected with ED2 but found the pin low. The simulator is showing the state of the P3^7 as high. And this problem exist not only in one hardware, but in all of my hardwares. May be this is the problem of 89C51ED2 Dip package, as I've used 89C51ED2 in PLCC44 package it works fine. Is this problem related with the built in XRAM or XEEPROM memory? Please help me.
Maaz Qazi
see answer at paralell post www.8052.com/.../read.phtml