Appendix 1: Status LEDs
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BASIC-programmable devices supplied by Tibbo have a pair of green and red status LEDs and/or control lines for connecting such LEDs externally. Particular status LED arrangement is product-specific, but these LEDs and/or their control lines are always implemented in one way or another.
Status LEDs have multiple functions:
•When the device is in the serial upgrade mode, these LEDs indicate the status of firmware upload process.
•When the device is under TiOS firmware control and Tibbo BASIC application is not running, these LEDs show current Tibbo BASIC application status.
•When the Tibbo BASIC application is running, status LEDs are under the control of the .pat object (see "TIDE and Tibbo BASIC Manual").
The following table summarizes predefined status LED blinking (flashing) patterns:
Ethernet status LEDs (when there are two of them)
Many Tibbo devices also have a pair of green and yellow Ethernet status LEDs and/or control lines for connecting such LEDs externally.
Ethernet status LEDs indicate the following:
•Link/Data LED (green) is turned on when "live" Ethernet cable is plugged into the device. The LED blinks whenever an Ethernet packet is received.
•100BaseT LED (yellow) is turned on when the device links with the hub at 100Mb. The LED is off when the link is established at 10Mb.
The EM500 and EM500EV devices do not have Ethernet status LEDs and the function of Ethernet state indication is performed by the status LEDs (status LED control lines) of these devices. These so-called dual-function status LEDs indicate the device state through familiar blinking (flashing) patterns, while LED brightness indicates the physical link state.
When "live" Ethernet cable is not plugged into the device, flashing patterns displayed by the status LEDs are "dimmed". That is, LEDs turn on at around 20% of their nominal brightness. When a "live" Ethernet cable is plugged into the device, flashing patterns are displayed at full brightness.
With this method of Ethernet status indication, there is no way to determine whether the link is established at 10 or 100Mb. This aspect, however, is of little importance these days because the majority of network hubs on the market are of the 100BaseT type.
Single Ethernet status LED
Some Tibbo devices only have a single Ethernet LED of yellow color. This LED is turned on when "live" Ethernet cable is plugged into the device. On some devices, the LED blinks whenever an Ethernet packet is received.