ccTalk Paylink Lite 2 User Manual
Aardvark Embedded Solutions Ltd.
Issue 1.1
3
rd
August 2018
Page 12
4.2 Onboard LED Operation
The onboard LED flashes at a nominal 1 Hz, and the different mark-space
ratios serve to indicate what the microcontroller is doing.
90% Mark-Space Ratio
When the LED is illuminated for 90% of the cycle, the microcontroller is
indicating that the USB traffic is normal.
The USB device is free to run normally.
50% Mark-Space Ratio
When the LED is illuminated for 50% of the cycle, the microcontroller is
indicating that the USB traffic has “just” ceased and that it is attempting
to reset the USB bus.
10% Mark-Space Ratio
When the LED is illuminated for 10% of the cycle, the microcontroller is
indicating that the USB traffic has failed for some time. It is attempting
to reset the USB bus, but at a much longer cycle time than when the
traffic first failed.
