Wiegand data and com port

[Yuantu Huang]

Dear Felch,

Thank you very much for your code. I am now implementing 8 card readers (both Track2 and variable length Weigand) on a single 16F737 using PICbasic Pro. Currently I have a problem for PIC18F8720 to access 2MB EMI using PICbasic Pro.

I will let you know once I implement 8 card readers on a single PIC.

Best regards,

[Felch]

Nice to hear that this piece of code is useful.
I was thinking about adding another proximity reader to the same PIC myself too but it was a little bit difficult. As you may have noticed, HID readers are critical: they give a very short pulse (about 40uS) but on the other hand their data "packet" lasts very long (about 70 mS!!).
Long packet is not a problem of course but it takes nearly 36uS for a PIC running @4MHz to branch form "everyday jobs" to card reading.
So if i have 2 readers active at the same PIC chip, it really puts it on the edge.

[alind]

Yuantu,
I was very interested to hear about your plan to implement 8 card readers.
How did you get on?
I am keen to do the same thing, but figured it would be necesary to have a seperate PIC for each reader...
Allan

Dear Felch,

Thank you very much for your code. I am now implementing 8 card readers (both Track2 and variable length Weigand) on a single 16F737 using PICbasic Pro. Currently I have a problem for PIC18F8720 to access 2MB EMI using PICbasic Pro.

I will let you know once I implement 8 card readers on a single PIC.

Best regards,

[Felch]

Hi!
I have recalculated things and...actually it is not very difficult. I can now read 2 RFID-s simultaneously. I have PIC16F628 running at 11.0592MHz (comm's crystal). RFID's generate a port change interrupt and first thing the int routine does is saving readers port data.
This is one possible way to solve the problem. Probably there are others as well.
/Felch

PS. I use assembly language, Basic seems to bee too slow.

[alind]

Felch,
I'd be keen to see your latest code for that.
I guess you use the USART port for one of the inputs.
I also use assembler. Check out my work, recompliing and adding SMTP and RTC support to a TCP/IP stack (with web browser) on a 18F452. It wasn't easy though.
http://al.joho.com

I am thinking of adding your Wiegand reader support to the stack to make a door access control system.
Allan

[Felch]

Hi!
My code is also used in a networked access system... I DID have to cut out some parts of it since i am not allowed to distribute it. Nevertheless i hope it will help you. Comments are in Estonian but code in pure assembly
I do not use UART for RFID-s but RB4...RB7 port's port change int.
Mail me if anything remains unclear or needs to be translated.

/Felch
PS. I am also working with radioactivity monitoring system. It will be something like a portable datalogger equipped with GPS. Data is stored on an MMS card. Presently busy with FAT code. How does your appartus look like?

EDIT: It crossed my mind that if you have your readers data-pins, say D0, wire-ored together to generate an RB0-int, then read (in the int routine) readers ports and save them for processing, one could service 8 or even more RFID-readers. May-be even simultaneously if PIC is fast enough. In the int routine one only needs to shift some bits, that's all!
This kind of approach seems to be used in commercial security systems.

EDIT: Mistake in circuit - BUZ and LED are actually B-readers datapins D0 and D1 .

[Yuantu Huang]

Hi Allan,

I am using PIC16F737 internal clock 8MHz, Card 1 is connected to RA6 and RA7, Cards 2, 3, and 4 are connected to PORTC<0:2,5:7>, and Cards 5,6,7,and 8
are connected to PORTB. All 16 card pins 1K resistors pull up to 5V.

I use the following code to determine which card has presented.

MainLoop:
CurrCard = 0
' Card reader 1
CheckPortA:
TempVar = PORTA
if TempVar < $C0 then CurrCard = 1 : goto FoundCard

' Card readers 5, 6, 7, and 8
CheckPortB:
TempVar = PORTB
if TempVar < $FF then
if TempVar.0 = 0 then CurrCard = 5 : goto FoundCard
if TempVar.1 = 0 then CurrCard = 5 : goto FoundCard
if TempVar.2 = 0 then CurrCard = 6 : goto FoundCard
if TempVar.3 = 0 then CurrCard = 6 : goto FoundCard
if TempVar.4 = 0 then CurrCard = 7 : goto FoundCard
if TempVar.5 = 0 then CurrCard = 7 : gosub FoundCard
CurrCard = 8
goto FoundCard
endif

' Card readers 2, 3, and 4
CheckPortC:
TempVar = PORTC
TempVar = TempVar & %11100111
if TempVar < %11100111 then
if TempVar.0 = 0 then CurrCard = 2 : goto FoundCard
if TempVar.1 = 0 then CurrCard = 2 : goto FoundCard
if TempVar.2 = 0 then CurrCard = 3 : goto FoundCard
if TempVar.5 = 0 then CurrCard = 3 : goto FoundCard
CurrCard = 4
goto FoundCard
endif

goto Mainloop

FoundCard:
select case CurrCard
Case 1: ' scan card 1
...
end select
...
goto Mainloop

[alind]

Thanks Felch and Yuantu, looks like I have plenty to get started with now!
Regards,
ALlan