hotel circuits

[Super_voip]

if you're going down the PIC path, why not have a PIC at each level to monitor the switches and then send to the Master PIC over RS485/422

 

[mayankguru]

if you're going down the PIC path, why not have a PIC at each level to monitor the switches and then send to the Master PIC over RS485/422

pls elaborate. . like which pic to go for . . so that i start reading that pic as i m new to controllers

 

[Super_voip]

for each floor or group of switches have a PIC monitor the switches, the PICs could be power by a low voltage AC feed in the same cable. RS485 being a balanced pair system should be immune to the AC. When a button is pressed the local PIC signals via the RS485 interface to the Master PIC which could either use a matrix to display individual LEDs or to 7 segment displays.
If you choose the central powered idea then very low powered PICs are needed if you power the PICs locally use any that will accomadate the number of switches required + the serial interface

 

[mayankguru]

reaally appreciate ur concern
thanks for the ideas. . .but bcoz of the time boundation. .i m going by this circuit .
**broken link removed**
only one problem with the circuit is:
if one of the 16 key is pressed the circuit is blocked till the key is released..
to sought out this problem i have dicided to go for that bell switch and to connect a hold IC 4013 at the output. . so it means that a switch will only b pressed for 2 seconds but the corresponding LED will remain glowing unless we press the reset button of the flip flop(ic 4013),and this way the circuit will also not get blocked . .

now the only issue left is that what if some one cut the cable from switch to mux. . .the whole thing will stop working . . . .

u guys being a great help till now. .
pls help

 

[pc88]

This is how they did it in 1890:

**broken link removed**

It's a one-wire, two-way communication system.