9 - Properties
eDynamo| Secure Card Reader Authenticator | Programmer’s Manual (COMMANDS)
Page 137 of 245 (
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9.4
Property 0x02 - USB Polling Interval (HID Only | KB Only)
Property ID:
0x02
Property Type: Byte
Length: 1 byte
Get Property: Yes
Set Property:
Yes
Default Value: 0x01
This one-byte value contains the device’s polling interval in milliseconds for the
Interrupt In
Endpoint,
can be between 1 - 255. The device sends the value of this property (if any) to the host during USB
device enumeration, and the host can use it to determine how often to poll the device for USB Input
Reports [see section
2.1.3 How to Receive Data On the USB Connection (HID Only)
]. For example, if
the polling interval is set to 10, the host polls the device for Input Reports every 10ms. This property can
be used to speed up or slow down the time it takes to send Input Reports to the host. The trade-off is that
speeding up the polling interval increases the USB bus bandwidth used by the device.
If the USB host hardware is configured to use a small keyboard buffer, the device may drop characters
and host software developers may use this setting to reduce the device’s transmission speed to
compensate. However, a better solution is to increase the host hardware’s keyboard buffer size. For
example, on a USB host with a buffer size of 100 bytes, increasing the buffer size to 1000 may allow
much shorter polling intervals resulting in faster transmission speeds without reducing reliability. For
details about adjusting keyboard buffer size, see the documentation about “Keyboard Buffer Size” for the
specific host hardware.
This property is stored in non-volatile memory, so it persists when the device is power cycled. When this
property is changed, the device must be reset (see
) or powered off for at
least 30 seconds, then powered on, before the changes will take effect.
Example Set Request (Hex)
Cmd Num
Data Len
Property ID
Property Value
01
02
02
0A
Example Set Response (Hex)
Result Code
Data Len
Data
00
00
Example Get Request (Hex)
Cmd Num
Data Len
Property ID
00
01
02
Example Get Response (Hex)
Result Code
Data Len
Property Value
00
01
01
