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Step 1: Get some Zynq based board. One On my desk was a ZYNQ XC7Z7045-FFG900 based board. That should do?
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And failed again, there are no LEDs available. They are missing in device-tree. Let's add the on-board LED to the device-tree. This can be done with utility called DTC. To my big surprise this tool is not at all available for Windows PC. Help... A few hours later I have DTC executable that works on Windows. My coworker who made it possible sends win32 patches to the maintainers of DTC tool, and I add theDTC.EXE to our download area.
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It is also of course possible to run DTC from Zynq Linux prompt as well, it seems to be available on all Zynq Linux versions. DTC.EXE is just a handy tool for windows host PC. |
for free downloads.
To de-compile binary device tree file to textual version we an can create a single line batch file DECOMPILE.BAT with this line inside:
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It is better to keep the decompile.bat in different directory after first decompile, as some changes to the textual device tree file will get lost if we accidentially accidentally decompile the blob in the same directory where the modified DTS file is. |
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And the LED on below 7045 is on as well...
But why was it needed to set MIO7 direction to out, if this pin is Output only? Well it is not usable as input, but Linux driver system does not know that it is output only and it listed with direction input initially.
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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