Usb Communication Protocol - Advanced Card ACR39x Reference Manual

7.0. USB Communication Protocol

ACR39x shall interface with the host through the USB connection. A specification, namely CCID, has
been released within the industry defining such a protocol for the USB chip-card interface devices.
CCID covers all the protocols required for operating smart cards.
The configurations and usage of USB endpoints on ACR39x shall follow CCID Rev 1.0 Section 3.
An overview is summarized below:
1. Control Commands are sent on control pipe (default pipe). These include class-specific
requests and USB standard requests. Commands that are sent on the default pipe report
information back to the host on the default pipe.
2. CCID Events are sent on the interrupt pipe.
3. CCID Commands are sent on BULK-OUT endpoint. Each command sent to ACR39x has an
associated ending response. Some commands can also have intermediate responses.
4. CCID Responses are sent on BULK-IN endpoint. All commands sent to ACR39x have to be
sent synchronously (e.g., bMaxCCIDBusySlots is equal to 01h for ACR39x).
The ACR39x supported CCID features are indicated in its Class Descriptor:
Offset
0
1 bDescriptorType
2
4
bVoltageSupport
5
6
10 dwDefaultClock
14 dwMaximumClock
18 bNumClockSupported
19
23 dwMaxDataRate
27 bNumDataRatesSupported
28
32 dwSynchProtocols
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ACR39x – Reference Manual
Version 1.03
Field Size
bLength
bcdCCID
bMaxSlotIndex
dwProtocols
dwDataRate
dwMaxIFSD
dwMechanical
Value Description
1 Size of this descriptor, in bytes.
1 CCID Functional Descriptor type.
CCID Specification Release Number in
2
binary-coded decimal.
1 One slot is available on ACR39x.
ACR39x can supply 1.8 V, 3 V, and 5 V to
1
its slot.
4 ACR39x supports T=0 and T=1 protocol.
4 Default ICC clock frequency is 4.8 MHz.
Maximum supported ICC clock frequency
4
is 4.8 MHz.
Does not support manual setting of clock
1
frequency.
4 Default ICC I/O data rate is 12918 bps.
Maximum supported ICC I/O data rate is
4
826 Kbps.
Does not support manual setting of data
1
rates.
Maximum IFSD supported by ACR39x for
4
protocol T=1 is 247.
ACR39x does not support synchronous
4
card.
ACR39x does not support special
4
mechanical characteristics.
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