Computer Interfacing

[sri_doeacc]

hi,
i am interfacing 8051 with max485.
b/w these ic's i am using analon mux for my application.
at my max485 (i am using 485 in half duplex mode)pins voltages.
RO 4.7V
DE &RE/ .7V
DI 3.0V
A = 0.6V
B = 0.6V
MY problem is i am not getting data on hyperterminal what i have placed on SBUF for transmitting from 8051 to hyperterminal.
please help me.

[engineer.amir@hotmail.com]

1) connect RO pin with RXD pin of 8051
2) connect DI pin with GND
3) short pins DE & RE together and connect them with the collector of transistor (like C337)
4) connect TXD pin of 8051 with the base of transistor

5) Pin no 8 with VCC
6) pin no 5 with GND
7) pin no 6 with pull up resistor of 1k (A)
8) Pin no 7 with pull down resistor of 1k (B)
9) use 100ohm resistor between pin 7 and 6

now this is working circuit and i am also using it for software you first study master/slave communication of 8051

Regards
Amir Rashid
NADRA HQ
Islamabad - PAK