LZ85202
IrDA Control Host Controller with USB Interface User
’
s Guide
25
In other words, the IrDA Control keyboard must periodically send the data to the USB Dongle
every 220 ms. Figure 13 shows the Auto Repeat Cancellation Function for Key board.
Status Explanation
‘
A
’
to
‘
D
’
in Figure 13
A Status: The USB Dongle tries to send
‘
key release
’
code to the Host device, as 220 ms
has already passed after receipt of the
‘
key stroke
’
without receiving a
‘
key release
’
code. But the IrDA Control keyboard continues sending another
‘
key stroke
’
code to the
USB Dongle before reaching status A. In this case, the USB Dongle will not send the
‘
key release
’
code to the Host devices, and the system enters to the
‘
Auto Repeat
’
mode.
Showing the same character, or keep performing the same command.
B Status: The IrDA Control keyboard is in the condition where a certain key is kept
pressed. In the status of A and B, the IrDA Control keyboard periodically sends a
‘
key
stroke
’
data to the USB Dongle.
C Status: The Assume IR link is intercepted between the IrDA Control keyboard and the
USB Dongle. In this condition, the USB Dongle cannot receive the
‘
key stroke
’
data from
the IrDA Control keyboard.
D Status: The USB Dongle should receive the
‘
key stroke
’
data from the IrDA Control
keyboard, but prevented because of losing the IR link in status C. The USB Dongle can-
not receive the
‘
key stroke
’
data. At this point, the USB Dongle recognizes the situation
as the IrDA Control keyboard is disconnected, and sends the
‘
key release
’
data to the
Host devices to cancel the Auto Repeat mode for the IrDA Control keyboard.
Specifications
Peripherals are distinguished with the keyboard bit of PFID. The report mechanism for the
keyboard keys are assumed to conform to the boot device format defined in the USB spec-
ifications.
1. All
‘
0
’
s in the report data represents the key release. Thus, the key release code gen-
erated by the HC also conforms to this definition.
2. In case of keyboard with pointing device capability, HC will recognize Endpoint 1
as keyboard.
Figure 13. Sequence of Auto Repeat Cancellation for Keyboard
LZ85202-13
(220 ms)
(B +
α
ms)
(B + 220
α
ms)
A
KEY STROKE
START
KEY STROKE
(Key Pressed Condition)
INFRARED
COMMUNICATION
DISCONNECTED
(Key Pressed Condition)
B
C
D
TIME: T