Rainbow Electronics AT89C5122 User Manual
Page 80
80
AT8xC5122/23
4202E–SCR–06/06
Reset Value = 0X00 0000b
Table 45. Smart Card Contacts Register - SCCON (S:ACh, SCRS=0)
7
6
5
4
3
2
1
0
CLK
-
CARDC8
CARDC4
CARDIO
CARDCLK
CARDRST
CARDVCC
Bit Number
Bit Mnemonic
Description
7
CLK
Card Clock Selection
Clear this bit to use the Card CLK bit (CARDCLK bit below) to drive Card CLK (P1.4) pin.
Set this bit to use CK_XTAL1 or CK_PLL signals for CK_ISO to drive the Card CLK pin (CCLK = P1.4 pin)
Note: internal synchronization avoids glitches on the CLK pin when switching this bit.
6
-
Reserved
This bit can be changed by software but the read value is indeterminate.
5
CARDC8
Card C8
Clear this bit to drive a low level on the Card C8 pin (CC8 = P1.1 pin).
Set this bit to set a high level on the Card C8 pin (CC8 = P1.1 pin)..
The CC8 pin can be used as a pseudo bi-directional I/O when this bit is set.
Warning : VCARDOK=1 (SCISR.4 bit) condition must be true to change the state of CC8 pin
4
CARDC4
Card C4
Clear this bit to drive a low level on the Card C4 pin (CC4 = P1.3 pin).
Set this bit to set a high level on the Card C4 pin (CC4 = P1.3 pin).
The CC4 pin can be used as a pseudo bi-directional I/O when this bit is set.
Warning : VCARDOK=1 (SCISR.4 bit) condition must be true to change the state of CC4 pin
3
CARDIO
Card I/O
If UART bit is cleared in SCICR register, this bit enables the use of the Card IO pin (CIO = P1.0) as a C51
pseudo bi-directional port :
To read from CIO (P1.0) port pin : set CARDIO (P1.0) bit then read CARDIO (P1.0) bit to have the CIO port
value
To write in CIO (P1.0) port pin : set CARDIO (P1.0) bit to write a 1 in CIO (P1.0) port pin , clear CARDIO (P1.0)
bit to write a 0 in CIO (P1.0) port pin.
Warning : VCARDOK=1 (SCISR.4 bit) condition must be true to change the state of CIO pin
2
CARDCLK
Card CLK
When the CLK bit is cleared in SCCON Register, the value of this bit is driven to the Card CLK pin.
Warning : VCARDOK=1 (SCISR.4 bit) condition must be true to change the state of Card CLK pin
1
CARDRST
Card RST
Clear this bit to drive a low level on the Card RST pin.
Set this bit to set a high level on the Card RST pin.
Warning : VCARDOK=1 (SCISR.4 bit) condition must be true to change the state of Card RST pin
0
CARDVCC
Card VCC Control
Clear this bit to desactivate the Card interface and set its power-off. The other bits of SCCON register have no
effect while this bit is cleared.
Set this bit to power-on the Card interface. The activation sequence should be handled by software.