SmartCard and BasicStamp

ftj405

I'm using a Parallax smart card and parallax smart card reader board with my bs2.

I turn on and off Status LEDs depending on the situation.

1. If the card is not present. (RED)
2. Card Inserted (Yellow)
3. Reading or writing will be GREEN.

the issue i have is that the CD (Card Detector) only detects if the card is present or inserted, not if its in the wrong way. So if you go to read the card and its inserted wrong it hangs.

I'm modifying some of the sample code i download. Once the card is installed correctly can i get a signal from the SCard CLK pin?

Sample code

DeviceStart: ' I2C start bit sequence
INPUT IO
INPUT CLK
LOW IO
Clock_hold:
DO : LOOP UNTIL(CLK=1)
RETURN

And if its not installed correctly could I not just stop waiting for the CLK to signal?

Thanks Ahead of time

ftj405

I found an answer to my own question.

Since the orientation of the card needs to be checked upon a CardDetect, the bus will not be busy and the card should be able to send a quick acknowledgement. If the card is put in incorrectly no acknowledgement is received and the user is notified and the program ends.


I copied and modified the code below and placed the call after the card detect.
' {$STAMP BS2}
' {$PBASIC 2.5}

'ReadDataFromSCToSerialOut_1010
'read/write data over serial line to and from smart card.
' TJ Treinen 09/11/2010
' SER_1.BS2
'

---

[ I/O Definitions ]

---

IO PIN 3 ' Serial Data IO
CD PIN 2 ' Card Detect
CLK PIN 1 ' Serial Data Clock

'

---

[ Constants ]

---

Ack CON 0 ' Acknowledge - Successful data transfer
NAck CON 1 ' Acknowledge - Unsuccessful data transfer

'

---

[ Variables ]

---

index VAR Word ' Variable space for FOR..NEXT loop
command VAR Byte ' Read/Write designation
wData VAR Byte ' Write data
rData VAR Byte ' Read data

I2CAck VAR Bit ' Acknowledge bit
temp VAR Byte ' Variable space
address VAR Word ' Current address loaction
page VAR Nib ' Current

'

---

[ Serial Vars ]

---

CHOICE VAR Byte(8)
MENUITEM VAR Nib
POS VAR Nib
idx VAR Byte
value VAR Byte

'DIRS = $00FF

POS = 0
CD = 0

Main:

DO
GOSUB POLLFORCARD
GOSUB CheckDevice
GOSUB Page_Choice


LOOP
GOTO ExitProgram

'

---

[ Initialization ]

---

' Declares PSC and waits for a smart card to be inserted
POLLFORCARD:
DEBUG CLS
DO ' Check for smart card,
DEBUG HOME, "No card inserted!", CR, LF
LOOP UNTIL(CD = 1)
RETURN

CheckDevice: ' I2C start bit sequence
GOSUB DeviceStart ' Call start condition
temp = %10100000 ' Device Address %1010AAA(W)
command = address.HIGHBYTE << 1
command = command & %00001110 ' Device Address %1010AAA(R) and ROM Address
temp = temp | command ' Add the ROM address into the Command
GOSUB SendOut
IF (I2CAck=NAck) THEN
GOTO InvalidInsert
ELSE
RETURN
ENDIF

ExitProgram:
END


<<

---

other code not part of the explanation was here

---

>

'

---

[ Subroutine - Page_Choice ]

---

' During 'read' selection, allows user to browse through each 16-byte page of data
Page_Choice:
DO
DEBUG CR, "Select new page [1-8], or press [9] to return to menu: "
DEBUGIN DEC page

SELECT page
CASE 1 TO 8: GOTO Read_Data
CASE 9: RETURN
CASE ELSE: DEBUG "Invalid Selection", CLREOL
ENDSELECT
LOOP
RETURN



'

---

[ Subroutine - DeviceStart ]

---

DeviceStart: ' I2C start bit sequence
INPUT IO
INPUT CLK
LOW IO
Clock_hold:
DO : LOOP UNTIL(CLK=1)
RETURN

'

---

[ Subroutine - DeviceStop ]

---

DeviceStop: ' I2C stop bit sequence
LOW IO
INPUT CLK
INPUT IO
RETURN

'

---

[ Subroutine - SendOut ]

---

SendOut: ' Send out a byte and get acknowledge
SHIFTOUT IO, CLK, MSBFIRST, [Temp\8]
SHIFTIN IO, CLK, MSBPRE, [I2CAck\1]
RETURN

'

---

Receive a Byte

---

Receive_NAck:
I2CAck = NAck

InvalidInsert:
GOSUB DeviceStop
LOW 13
HIGH 15
PAUSE 1000
SEROUT 16, 84, 10, [LF, CR, "Card Inserted incorrectly. Remove and Try Again", LF, CR]
LOW 15
GOTO ExitProgram