Thanks Luigi ! That helped me so much. It's a great clue!
On Thursday, June 13, 2013 at 1:12:36 PM UTC+4:30, Luigi Rinaldi wrote:
>
> I had the same problem, I resolved it exporting at least one pin for each
> GPIO. After that I can access GPIO0, GPIO2 and GPIO3 with mmap.
> It's not about pinmux, maybe the problem is the clock.
> Try to do this:
> # echo 5 > /sys/class/gpio/export
> # echo 65 > /sys/class/gpio/export
> # echo 105 > /sys/class/gpio/export
> You can do it also in C++ or Python.
>
> Luigi Rinaldi.
>
> Il giorno mercoledì 12 giugno 2013 04:41:10 UTC+2, Jacek Radzikowski ha
> scritto:
>>
>> Hello,
>>
>> I'm getting bus errors whenever my program tries to access registers
>> controlling pins on GPIOs 0,2 or 3. I'm not trying to set pinmuxing, I
>> try to write to registers controlling the pins.
>> GPIO1 works fine and I can enable outputs by writing to the OE
>> register and change the values on the pins by writing to the OUT
>> register.
>>
>> Here are some details of my simple test program:
>> The base addresses for the GPIO blocks are defined as follows:
>> const uint32_t gpioAddrs[] =
>> { 0x44E07000, 0x4804C000, 0x481AC000, 0x481AE000 };
>>
>> The memory blocks are mapped to process address space with the following
>> mmap:
>> gpios[i] = (uint32_t *) mmap(NULL, 0xfff,
>> PROT_READ | PROT_WRITE, MAP_SHARED, gpioFd,
>> gpioAddrs[i]);
>>
>> Printing values from OE, IN and OUT registers:
>> printf("i=%i\n",i);
>> printf("OUT[%i]=0x%08x\n",i,gpios[i][DATA_OUT_REG/4]);
>> printf("IN[%i]=0x%08x\n",i,gpios[i][DATA_IN_REG/4]);
>> printf("OE[%i]=0x%08x\n",i,gpios[i][GPIO_OE_REG/4]);
>>
>> The full source is on gist:
>> https://gist.github.com/piranha32/4fd285cc8333eeb4ec39
>>
>> Program works fine when 'i' is set to 1, crashes for 'i' set to 0,2 or 3.
>> Am I missing something obvious, or is this an overzealous memory
>> protection?
>>
>> Board: BBBlack
>> Kernel: Linux beaglebone 3.8.13 #1 SMP Fri Jun 7 09:49:12 CEST 2013
>> armv7l GNU/Linux
>>
>> thx,
>> j.
>>
>>
>> --
>> Given a choice between two theories, take the one which is funnier
>>
>
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