Communication protocol – ACS ACR33U-A1 SmartDuo Smart Card Reader User Manual
Page 10
ACR33U-A1 – Reference Manual
Version 1.02
www.acs.com.hk
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7.0. Communication Protocol
ACR33U-A1 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 ACR33U-A1 shall follow CCID 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 ACR33U-A1 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 ACR33U-A1 have to
be sent synchronously (e.g., bMaxCCIDBusySlots is equal to 01h for ACR33U-A1).
The ACR33U-A1 supported CCID features are indicated in its Class Descriptor:
Offset
Field
Size
Value
Description
0
bLength
1
36h
Size of this descriptor, in bytes
1
bDescriptorType
1
21h
CCID Functional Descriptor type
2
bcdCCID
2
0100h
CCID Specification Release Number in
Binary-Coded decimal
4
bMaxSlotIndex
1
05h
2 big slots and 3 SAM slots are available
on ACR33U-A1
5
bVoltageSupport
1
01h
ACR33U-A1 can supply 5 V to its slot
6
dwProtocols
4
00000003h ACR33U-A1 supports T=0 and T=1
protocol
10
dwDefaultClock
4
00000FA0h Default ICC clock frequency is 4 MHz
14
dwMaximumClock
4
00000FA0h Maximum supported ICC clock
frequency is 4 MHz
18
bNumClockSupported
1
00h
Does not support manual setting of
clock frequency
19
dwDataRate
4
00002A00h Default ICC I/O data rate is 10752 bps
23
dwMaxDataRate
4
00054024h Maximum supported ICC I/O data rate is
344100 bps
27
bNumDataRatesSupported
1
00h
Does not support manual setting of data
rates
28
dwMaxIFSD
4
00000FEh Maximum IFSD supported by ACR33U-
A1 for protocol T=1 is 254
32
dwSynchProtocols
4
00000000h ACR33U-A1 does not support
synchronous card
36
dwMechanical
4
00000000h ACR33U-A1 does not support special
mechanical characteristics