AT89C5122 ATMEL [ATMEL Corporation], AT89C5122 Datasheet - Page 80

• Manufacturer Part Number: AT89C5122
• Description: MICROCONTROLLER WITH USB AND SMART CARD READER INTERFACES
• Manufacturer: ATMEL [ATMEL Corporation]

Table 45. Smart Card Contacts Register - SCCON (S:ACh, SCRS=0)
Reset Value = 0X00 0000b
80
Bit Number
CLK
7
7
6
5
4
3
2
1
0
AT8xC5122/23
Bit Mnemonic
CARDVCC
CARDRST
CARDCLK
CARDC8
CARDC4
CARDIO
6
CLK
-
-
Description
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.
Reserved
This bit can be changed by software but the read value is indeterminate.
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
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
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
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
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
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.
CARDC8
5
CARDC4
4
CARDIO
3
CARDCLK
2
CARDRST
1
4202D–SCR–06/05
CARDVCC
0