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LZ85202
12
IrDA Control Host Controller with USB Interface User
’
s Guide
USB Protocol Process (USB Module)
In general, data exchanges between the Host device and the USB peripheral uses three
different types of data, which are: TALKN packet (IN /OUT packet), data packet (packet of
DATA0 and DATA1), and handshake packet (ACK, NAK and STALL).
In the IrDA Control data communication system, the HC
’
s internal USB module controls
the protocols for the three different types of data packets, and takes the role of data trans-
action bridge to the Dongle Driver (see the
‘
Dongle Driver
’
section).The following section
describes the USB protocol process by the HC.
Endpoint
The IrDA Control Endpoints listed in Table 1 are available on the HC.
The Endpoint is a concept in USB, which represents both ends of the communication
flow between the USB Host and the devices, recognized as one communication path
and/or channel.
Pipe is originally a concept that represents the logical communication channel itself. The
types of the pipe are based on the Endpoints in Table 1, EP0 is the control pipe, EP1 and
EP3 are data pipes (IN).
Suspend Mode and Remote Wake-up
Suspend and Resume are the functions supported by the regular USB device.The current
HC can support the remote wake-up function if it meets the conditions given below.
If the Host is in stand-by mode, and the USB Dongle is externally power supplied, the
remote wake-up function will be supported. The USB Dongle has a function to make the
Host resume when it receives a data from the peripheral during its suspend status.
Operation Mode (USB Configuration)
In an IrDA Control communication system, the USB Dongle implemented with the HC has
two operation modes. One is
‘
Emulation Mode
’
, the other is
‘
Bridge Mode
’
. When booting
the Host PC, the configuration value for the USB Dongle is first set to
‘
1
’
, which represents
the Emulation Mode. After Windows 98 operating system is booted, and the
‘
Dongle
Driver
’
(see the
‘
Dongle Driver
’
section) is loaded to the operating system, the configura-
tion value of the USB Dongle will then set to
‘
2
’
, which represents the Bridge Mode.
Table 1. Endpoint
ENDPOINT
TRANSFER METHOD
Control (OUT)
Control (IN)
Interrupt (IN)
Interrupt (IN)
DESCRIPTION
EP0
Used for USB-Enumeration information exchange in
IrDA Control protocol.
EP1
EP3
Send data from the Peripheral to the Host.
Send data from the Peripheral to the Host.