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Advanced users • Re: using readl() to read GPIO MMIO always returns 0 values

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thanks, will try with the address reported by pinctrl, that is indeed 0x20200000 BCM2835.
quite strange that the gpio.py using 0x3F200000 reported bit changes when plugging the test high level on a pin on the corresponding bit.
as if the mapping from the bus to physical memory was preserved for compatibility ??

As for the source of that info, I will check, i think i crossed checked various site sources and LLMs. There was quite a bit of confusion between them for sure. (some sources mixup bcm IC address spaces and raspberry pi physical memory as well as what model uses what BCM chip)

Statistics: Posted by rodv92 — Wed Aug 06, 2025 3:04 pm



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