Rainbow Electronics T89C5121 - Manual (Page 30)

30
A/T8xC5121
4164G–SCR–07/06
Block Diagram The Smart Card Interface Block diagram is shown in Figure 14.
Figure 14. SCIB Block Diagram
Functional Description The architecture of the Smart Card Interface Block is detailed below.
Barrel Shifter It allows the translation between 1 bit serial data and 8 bits parallel data.
The barrel function is useful for character repetition since the character is still present in
the shifter at the end of the character transmission.
This shifter is able to shift the data in both directions and to invert the input or output
value in order to manage both direct and inverse ISO7816-3 convention.
Coupled with the barrel shifter there is a parity checker and generator.
There are 2 registers connected to this barrel shifter, one for the transmission and one
for the reception.
They act as buffers to relieve the CPU of timing constraints.
SCART FSM (Smart Card Asynchronous Receiver Transmitter Finite State Machine)
This is the core of the design. Its purpose is to control the barrel shifter. To sequence
correctly the barrel shifter for a reception or a transmission, it uses the signals issued by
Barrel shifter
SCI Registers
Scart
fsm
Interrupt generator
Power on
Power off
fsm
I/O
mux
IO (in)
IO (out)
CLK
RST
C4 (out)
Clk_iso
C8 (out)
CLK1
C4 (in)
C8 (in)
Waiting time
counter
Guard time
counter
Etu counter
VCARD
INT
Clk_cpu