Rainbow Electronics DS8314 - Manual (Page 10)

DS8313/DS8314
If the card is in the reader (if PRES is active), the host
microcontroller can begin an activation sequence (start
a card session) by pulling CMDVCC low. The following
events form an activation sequence (Figure 3):
1) CMDVCC is pulled low.
2) The internal oscillator changes to high frequency (t 0 ).
3) The voltage generator is started (between t 0 and t 1 ).
4) V CC rises from 0 to 5V, 3V, or 1.8V with a con-
trolled slope (t
2
= t
1
+ 1.5 × T). T is 64 times the
internal oscillator period (approximately 25µs).
5) I/O pin is enabled (t 3 = t 1 + 4T) (they were previ-
ously pulled low).
6) The CLK signal is applied to the C3 contact (t 4 ).
7) RST is enabled (t
5
= t
1
+ 7T).
To apply the clock to the card interface:
1) Set RSTIN high.
2) Set CMDVCC low.
3) Set RSTIN low between t 3 and t 5 ; CLK will now start.
4) RST stays low until t 5 , then RST becomes the copy
of RSTIN.
5) RSTIN has no further effect on CLK after t
5
.
If the applied clock is not needed, set CMDVCC low
with RSTIN low. In this case, CLK starts at t
3 (minimum
200ns after the transition on I/O, see Figure 4); after t 5 ,
RSTIN can be set high to obtain an answer to request
(ATR) from an inserted smart card. Do not perform acti-
vation with RSTIN held permanently high.
Active Mode
When the activation sequence is completed, the card
interface is in active mode. The host microcontroller
and the smart card exchange data on the I/O lines.
Smart Card Interface
10 ______________________________________________________________________________________
ATR
CMDVCC
RST
RSTIN
CLK
V
CC
I/O
I/OIN
t
0
t
1
t
2
t
3
t
4
t
5
= t
ACT
Figure 3. Activation Sequence Using RSTIN and CMDVCC