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ACR38x Reference Manual (CCID)
Version 6.02
Page 8 of 20
www.acs.com.hk
6.0. USB Interface
ACR38x can be connected to a computer through a USB that follows the USB standard.
6.1. Communication Parameters
The ACR38x is connected to a computer through USB as specified in the USB Specification 2.0. The
ACR38x is working in full speed mode, i.e. 12 Mbps.
Pin
Signal
Function
1
V
BUS
+5V power supply for the reader
2
D-
Differential signal transmits data between ACR38x and PC.
3
D+
Differential signal transmits data between ACR38x and PC.
4
GND
Reference voltage level for power supply
Table 1.
USB Interface Wiring
Note:
In order for the ACR38x (CCID) to function properly through USB interface, the ACS CCID driver
or the Microsoft CCID Driver should be installed.
6.2. Endpoints
The ACR38x uses the following endpoints to communicate with the host computer:
Control Endpoint
For setup and control purposes
Bulk OUT
For command to be sent from host to ACR38x (data packet size is 64 bytes)
Bulk IN
For response to be sent from ACR38x to host (data packet size is 64 bytes)
Interrupt IN
For card status message to be sent from ACR38x to host (data packet size is
8 bytes)
