W90P710_05 Datasheet, PDF (458/526 Pages) Winbond – 16/32-bit ARM microcontroller

W90P710
incoming data. Software driver needs to interpret initial character of ATR first to determine which
convention is for inserted card and chooses a conversion procedure for it. Subsequent incoming data
bytes must be passed through a conversion procedure before actually transfers these data bytes to
host. Similar conversion procedure must be applied to outgoing data byte before writing to TBR too.
For example, the raw data byte for initial character of inverse-convention ATR would be 3Fh.
Software driver therefore needs a conversion procedure to reverse bit-significance and polarity to
process subsequent raw data bytes. On the other hand, initial character of direct-convention ATR is
3Bh which needs no conversion procedure to process data byte.
z Data transfer
Software driver might need to configure control registers again based on information contained in ATR
before process subsequent data transfer. The following guidelines are provided for programming
reference.
1. EPE should be set to "1" for direct-convention card and otherwise for inverse-convention card.
2. BLH, BLL and CBR should be set to comply with Fi and Di.
3. GTR is used for various stop bit requirement of different transmission protocols.
4. Use interrupt resources to control communication sequence.
5. Monitor SCSR for transmission integrity.
z Cold reset and warm reset
Cold reset is achieved by writing a "1" to PWRDN (bit 7 of IER). It deactivates SCPWR# to high.
Consequentially, SCRST# is pulled down and SCCLK is stopped. User must write a "0" to PWRDN
(bit 7 of IER) to resume Smart Card interface to a normal activation state assuming card is still
present. The activation sequence and deactivation sequence are done by internal F.S.M
When in a normal activation state, writing a "0" SCRST_L (bit 1 of TMR) will force SC_RST pin to low
that will triggers a warm reset. Its effect is similar to cold reset except SCPWR# is kept activated and
therefore power supply to card stays on.
z Power states
SCHI employs a sophisticated algorithm to partition Smart Card interface's internal circuits to achieve
optimal power utilization. However, users must pay extra care in the design of application circuits
following guidelines stated below to prevent potential signal conflict and unnecessary power
consumption.
There're three power states: disabled state, active state, and power down state. Disabled state is the
default state when power is first applied to the IC. SCPWD (Smart Card Power Down) controls
whether in active state (SCPWD = 0) or in power down state (SCPWD = 1).
z Disabled state
Smart Card interface is in disabled state initially. Clock is stopped in this state and therefore it is the
least power-consuming state. To prevent current leakage from floating connections, it is designed to
output a predetermined voltage level on all the I/O pins of Smart Card interface as follows:
SCPWR# outputs high to disable power supply to socket;
SCRST#, SCCLK, and SCIO output low;
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