User Leds - Eurotech Apollo User Manual

User LEDs

Two connections for LEDs are provided on the front panel interface connector, these can
be used as indicators and are accessed through a register in the runtime register block. If
enabled these LEDs will remain illuminated whenever standby power is available and are
not cleared during a reset event.
The pin connections for the LED allow the user to turn the LEDs on and off and blink
independently of each other. Both versions of the APOLLO board utilize the same
register address for LED control.
IO address
LED1: Base address + 5Dh
LED2: Base address + 5Eh
The LED connections are designed to power LEDs with a forward voltage drop of 1.5V,
most LEDs fall into this category, the exception being blue LEDs which require a higher
forward voltage, typically 4V to be illuminated.
The following figure shows the correct connection of a user supplied LED a 330Ω resistor
is provided on the APOLLO board so that a direct LED connection can be made.
Issue G
Detailed hardware description
Bit Description
7:2 Reserved
1:0 LED control
00 = Off
01 = Blink, 1Hz rate with 50% duty
cycle (0.5 sec on, 0.5 sec off)
10 = Blink, ½ Hz rate with 25%
duty cycle (0.5 sec on, 1.5
sec off)
11 = On
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