Help finding Crosspoint Switch?

[muddy0409]

Hi all.
I am desperately searching for some 4 x 4 crosspoint switch chips. There are plenty of them around, but only in LARGE quantities. Does anyone know where I can get hold of 20 or so. Most popular seems to be 22100 by STMicrosystems or MC142100 by motorola.
I just don't wanna have to use 4 x 4066 where one of these, or similar would be perfect.
I am automating keypad presses.

Regards,
Peter Moritz,
Up the bush, Halfway to the outback, South Australia.

[Archangel]

Mouser has them .48 usd in single qty. See link below


http://www.mouser.com/search/Refine....user_Wildcards

[muddy0409]

Mouser don't stock them. Their MOQ is 1000, already tried to order from them but had to cancel when I heard the MOQ!

Thanks anyway.

[Archangel]

Mouser don't stock them. Their MOQ is 1000, already tried to order from them but had to cancel when I heard the MOQ!

Thanks anyway.

Is the MOQ because you are in Australia, because the link I posted says they have them in single order quantities. Perhaps someone here could run interference for you.

[Acetronics2]

Hi, muddy

Did you had a look for the old 74C922 ??? some still available.

RCA also had the CD 22100 ...

Alain

[skimask]

Hi, muddy

Did you had a look for the old 74C922 ??? some still available.

RCA also had the CD 22100 ...

Alain

I got a few of those, a bit expensive compared to other chips. These days, I take an old 16F84, program it accordingly, and send out key presses as a serial code.

[Acetronics2]

I am automating keypad presses.

.

Hi, Peter


This last sentence rang the alert bell ...

Could we know a bit more ???

Alain

[muddy0409]

Sure.
An associate of mine has asked about the possibility of adding RFID cards to the alarm systems he installs, as he has had some enquiries from customers.
My plan is to have a PIC read an RFID card and have the PIC drive a crosspoint switch wired accross the alarm keypad to "simulate" keypresses.
I have the reading and driving all worked out but now need a Xpoint switch so I can design a PCB (size constraints).
As a "just in case" I am looking, this weekend, at using 4066 chips (3 of them) connected as Xpoint array 4 X 3.
With the difficulty I am having finding some, that will probably be the solution.

See?
Simplicity itself huh?
(Well it is after getting some help on some problems from people in this very good forum.)

I've got the code basically sorted out (it works on my Development board, anyway) and am just waiting now to do a cuppla PCBs.

And NO, I cannot get any information from the manufacturer regarding their LAN format for the keypad to panel comms.
I have had it displaying on a terminal, but I cannot make any sense out of the data I see going back and forth.

The keypad and panel are both built around PICs.

Regards,
Peter Moritz.

[Acetronics2]

Hi,Muddy

Was a good idea to ask you for the context ...

What about a CD 4052 "Dual 4 Channel Multiplexer" ??? One half for the rows and one half for the lines ...

just need 5 lines ( 4 + enable both ...) from the driving PIC ...

Alain

[keithdoxey]

Hi Peter,

Instead of 3 x 4066 have you thought of using TWO x 4051 "back to back" instead. 4051s are common enough and cheap enough to be around for a long time yet

Provided the combined series resistance of two crosspoints is low enough to drive the keypad you can use that to address a keypad of upto 8 x 8.

To drive the 4066's you will need quite a few I/O lines or some form of IO expander whereas with the 4051 method you only need 6 lines for a 64 key 8x8 matrix and in your case get away with only 4 IO lines.

Mux "a" on the rows using a & b address lines with line c tied to 0v
Mux "b" on the columns using a & b address lines with line c tied to 0v

connect the "common" terminal of each mux together.

4051 is also available as an SMDso you can fit a pair of them in the same space that a normal DIP would take if you need to.

[keithdoxey]

What about a CD 4052 "Dual 4 Channel Multiplexer" ??? One half for the rows and one half for the lines ...

just need 5 lines ( 4 + enable both ...) from the driving PIC ...

Alain

I would have suggested that but 4052 is intended for Stereo switching so both sides share a common address

( I am using the 4052 to give me 4 serial ports on a 18F452 )

Forgot about "Enable" on my solution but as only 3 out of 4 combinations would be used on the "column" select then the 4th option would give an open circuit so all done with 4 lines

[Acetronics2]

AAAAAAArggggghhh, damned !

you're right Keith !!! that needs two CMOS packages ... at least one 4052 and one 4053 or a pair of 4052 ... but can deal with 2 arrays !!! or, of course 2 x 4051 !!!

Alain

[BobK]

Hi Muddy,

Being an alarm installer by trade I tried doing this to a Napco MA3000 panel several years ago. After a couple of hours of trying different things including the 4066's on the keypad lines, I asked the guy I was doing this for for the version of software the panel was operating on. The latest version had a feature that allowed a zone input to be programmed to act as a keyswitch to arm and disarm the panel. It worked out great for the project. A wine cellar in a church basement where sometimes the people would forget to re-arm the system. My add-on watched for the door to close. If the system wasn't armed and the door was open, the add-on would sit and wait for the door to close. If the door was closed and they didn't turn the system on within 1 minute my add-on would re-arm the system.

I always look for ways to connect to a system that won't violate the U.L. Listing on the panel. Making something that would enter a code where you have modified the device could end up costing you should anything ever happen that could prevent the system from detecting whatever it is suppose to detect. Most systems today have wireless keyfobs. Perhaps you to tie into the contacts on the wireless key and use that to trigger the system. There are only a couple of systems that have a U.L. Listing on their wireless devices.

BobK

[muddy0409]

Yeah, we thought of the zone = keyswitch thing, but one of his many wants is for the panel to still be able to identify and report users/keyholders or whatever you call them over there.
So really the only way is to still operate the system via the keypad, albeit, by cheating!
He is aware of the possible legal ramifications of this, but is willing to accept the risk.
Anyway, that's HIS problem.
I'm just designing the thing, not doing any alterations to the panels or keypads.


Did the PCB last night/this morning (Yaaawwwnnn) using 4066's and was not as difficult as I thought it was gunna be. Got enough drive lines (10) from an 18 pin PIC, just gotta work out the mapping and plenty left over for the serial in from the prox reader (1). Did have to go double sided though, so these will have to be made commercially rather than "home brew".
BTW, the system is a CADDX CONTROLS NX unit so if you do happen to have any info on the data that goes between the panel and keypad, it would be appreciated.
The data stream uses only one line for both send and receive so it is easy to read it, but working out what means what is a bit beyond this little black duck. And besides, I ain't gettin' paid enuff.
The local distributors always say they can't supply anything along the lines on information, so..........................