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We can assign "events the LED" or just control the LED to be on or off. Please note that we can also control GPIO devices connected to I2C Bus as well (if they are I2C GPIO Class devices, or emulated I2C Device in CPLD connected to FPGA).

Why MIO7 you may ask? This is the most famous Zynq LED number ever seven: MIO7 is one of two MIO pins that are usable as OUTPUT Only and also in almost all Zynq designs MIO7 is in 3.3V MIO bank, so it is first candidate for a "User LED". In TE0720 MIO7 is connected to System Controller that as default connects to a LED. But the System Controller could also use the MIO7 as some signal from Zynq ARM Core, or route the MIO7 back to the Zynq PL Fabric, or use the MIO7 as FORCE reset or something else.

Zedboard OOB Design

The SD Card images delivered with zedboard (and available as OOB SD Card images) include a kernel 3.09 with GPIO-LEDS enabled on MIO7 with default trigger set to MMC (SD Card) activity. Writing none to LED trigger would allow direct programmatic control over MIO7 LED on zedboard (labelled LD9!). 

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