The AHB bus allows faster control of GPIO pins versus the older APB bus.
The GPIO ports A through H default on the APB bus. Change the GPIOx
defines in gpio.h to use the base address of the AHB bus.
There's another reason to use the AHB bus: ports K tand highercan only be
accessed via the AHB bus.
***WARNING***
To work, GPIO acces to the AHB bus must be explictly enabled via the
GPIOHBCTL register. Without any additional change, this patch will break
any code using the older APB bus. If the GPIOHBCTL is not properly
modified, any acces to the GPIO register will cause a hard fault.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
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