Hello kai

Thanks for replying what I understand goes as below any doubts still are also mentioned For clarifications I am mentioning and labelling the connectors as I will be referring them again and again as I have the option of getting another version
For pcb layout I can try to incorporate as many feedback as possible


Please refer images in same area(http://www.itasveer.com/pool/mani...52-images)
bot_side_conn_details.gif
top_side_conn_details.gif

Con1 :- (sv5 in sch) this connector contains my input activation signal also output may be I need to separate things and change position also, presently at first edge

CON2 & CON3:- o/ps of ULN2803 directly coming from pins , at first edge

CON4 :- again o/p of ULN2803 directly coming from pins, at second edge

CON5: - input port of one pcf 8574 at second edge

CON6:- output port of pcf 8574 at third edge

CON7: - LCD connector at fourth edge
CON8: - KEYPAD from P1

So in short all the edges are having connectors, the wires picked from in between the pcb are majorly gnd and vcc connections not planned before, but as now the complete routing is available they can be planned to move towards any one edge



1: Shielding and ground plane

Agree shielding can easily be adopted by using shielded cables , the only part of not using was saving cost and to have flexibility for different wire length needs at relay board side

2: 100 n caps,

As suggested by Erick the software now has debounce mechanism, which has shown improvement from those chattering noises, plan to remove from one nibble as suggested, also plan to change to a smaller value?

3: 12 volts

The wire for relay card is close to the o/ps of ULN, the other 12v used for ULN in boards come as a separate wire from source

4: PCB
Solid ground plane, please guide so as to what portion needs a ground plane only the micon part or what as there is limitation for using max double sided borad only so I feel this point difficult to implement but if sensitive areas are known I hope this can be done there
Many cables: are we saying the same for connectors also, as I mentioned the cables in this proto were not planned in pcb but next version can definitely have a suitable boundary place to leave the board, but if w include all the connectors in this category then without changing the aspect ration of the pcb it will be very difficult to route all those signal at edge when most of them are getting out from direct pins of IC’s

Metal enclosure yes the whole arrangement sits in metal body and the ground part is connected to that metal body, also as suggested the faraday cage enclose the micon pcb and is connected to gnd of micon board (image not available as done at other end)