Rainbow Electronics AT83C24NDS - Manual (Page 20)

20
4234F–SCR–10/05
AT83C24
Registers
Table 6. CONFIG0 (Config Byte 0)
7 6 5 4 3 2 1 0
1 0 ATRERR INSERT ICARDERR VCARDERR VCARD1 VCARD0
Bit
Number Bit Mnemonic Description
7-6 1-0 These bits cannot be programmed and are read as 1-0.
5 ATRERR
Answer to Reset Interrupt
This bit is set when the card clock counter overflows (no falling edge on CIO
is received before the overflow of the card clock counter).
This bit is cleared by hardware when this register is read. It can be set by
software for test purpose. The reset value is 0.
4 INSERT
Card Insertion Interrupt
This bit is set when a card is inserted or extracted: a change in CARDIN value
filtered according to CDS[2-0]. After power up, if the level on CPRES pin is 0,
then INSERT bit is set.
It can be set by software for test purpose.
This bit is cleared by hardware when this register is read. It cannot be cleared
by software.
The reset value is 0.
3 ICARDERR
Card Over Current Interrupt
This bit is set when an over current is detected on CVCC. It can be set by
software for test purpose (no card deactivation is performed, no IT is
performed).
This bit is cleared by hardware when this register is read. It cannot be cleared
by software.
The reset value is 0.
2 VCARDERR
Card Out of Range Voltage Interrupt
This bit is set when the output voltage goes out of the voltage range specified
by VCARD field. It can be set by software for test purpose and deactivate the
card.
This bit is cleared by hardware when this register is read. It cannot be cleared
by software.
The reset value is 0.
1-0 VCARD[1:0]
Card Voltage Selection
VCARD[1:0] = 00: 0V
VCARD[1:0] = 01: 1.8V (see STEPREG bit)
VCARD[1:0] = 10: 3V
VCARD[1:0] = 11: 5V
VCARD[1:0] writing to 1.8V, 3V, 5V starts the DC/DC if a card is detected.
VCARD[1:0] writing to 0 stops the DC/DC.
No card deactivation is performed when the voltage is changed between
1.8V, 3V or 5V. The microcontroller should deactivate the card before
changing the voltage.
The reset value is 00.