what is the process to access gpio for Jetson nano using qt creator On Thursday, June 5, 2014 at 4:20:43 AM UTC+6 [email protected] wrote:
> Two other features of going low level with mmap: > > Open drain output: By controlling the output enable registers, you > can do open drain by setting the output to drive 0, then enable output to > pull low, disable output to for high (with external pullup or internal > through pin muxing). > > Simultaneous toggling: You can set the pin states of a whole gpio > bank at once. This is nice if you're bit banging. > > 2.8MHz seems slow. I was at 4MHz through an mmap in *Python*. Make sure > you're using the set registers rather than doing a read-modify-write and > only opening the mmap once...and I suppose your clock scaling will matter > too, so maybe it's the same. > > --Brandon > > On Wednesday, June 4, 2014 2:26:32 PM UTC-7, john3909 wrote: >> >> >> From: Tony DiCola <[email protected]> >> Reply-To: <[email protected]> >> Date: Wednesday, June 4, 2014 at 8:29 AM >> To: <[email protected]> >> Subject: Re: [beagleboard] Beaglebone Black libraries for GPIO access in >> C/C++? >> >> Thanks for the replies everyone--looks like some nice libraries to check >> out. >> >> Regarding memory mapped GPIO, check out this nice blog post for more >> info: >> http://vabi-robotics.blogspot.com/2013/10/register-access-to-gpios-of-beaglebone.html >> >> You can effectively map the GPIO registers to a process' memory space and >> directly access them so there's no overhead of making the system calls to >> read, write, etc. the sysfs-based GPIO. >> >> I actually just tried out a couple quick tests and saw toggling a pin >> high and low in a tight loop with sysfs is pretty slow, only a few hunded >> khz. However using memory mapped GPIO registers it's much, much faster. >> I'm seeing around 2.8 mhz toggling a pin with this approach. Now neither >> approach is technically going to ever give you a real time guarantee of >> course, but it's nice to have the ability to read and write GPIO fairly >> quickly in some cases with memory mapped GPIO. >> >> The downside is you cannot support GPIO interrupts. >> >> Regards, >> John >> >> >> >> On Wed, Jun 4, 2014 at 5:00 AM, Micka <[email protected]> wrote: >> >>> William Hermans, how did you controlled the GPIO ? >>> >>> The only way that I know is with : >>> >>> >>> /sys/class/gpio/gpio%d/value >>> >>> >>> but you talk about mmap ? How did you use it with this >>> /sys/class/gpio/gpio%d/value ? >>> >>> Thx you, >>> >>> Micka, >>> >>> >>> >>> >>> On Tue, Jun 3, 2014 at 11:57 PM, William Hermans <[email protected]> >>> wrote: >>> >>>> sysfs, and mmap. I've seen mention of both on the web ( including for >>>> the BB white ). >>>> >>>> *wiringPi* >>>>> >>>> >>>> Whats this ? The Arduino IDE for the rPI ? Nothing like this exists for >>>> the BBB that I am aware of. >>>> >>>> >>>> On Tue, Jun 3, 2014 at 2:45 PM, Jacek Radzikowski < >>>> [email protected]> wrote: >>>> >>>>> <shameless plug> >>>>> https://github.com/piranha32/IOoo >>>>> </shameless plug> >>>>> >>>>> j. >>>>> >>>>> >>>>> On Tue, Jun 3, 2014 at 5:42 PM, Tony DiCola <[email protected]> >>>>> wrote: >>>>> > Sorry if this is a common question, but I've searched around the web >>>>> and the >>>>> > forum here and am curious are there any somewhat mature or popular >>>>> libraries >>>>> > for simple digital GPIO access on the Beaglebone Black in C/C++? I'm >>>>> > curious if there's anything like wiringPi or similar for the BBB >>>>> yet. If >>>>> > not, are folks just rolling their own thing with access to sysfs or >>>>> mmap? >>>>> > >>>>> > -- >>>>> > For more options, visit http://beagleboard.org/discuss >>>>> > --- >>>>> > You received this message because you are subscribed to the Google >>>>> Groups >>>>> > "BeagleBoard" group. >>>>> > To unsubscribe from this group and stop receiving emails from it, >>>>> send an >>>>> > email to [email protected]. >>>>> > For more options, visit https://groups.google.com/d/optout. >>>>> >>>>> >>>>> >>>>> -- >>>>> Given a choice between two theories, take the one which is funnier >>>>> >>>>> -- >>>>> For more options, visit http://beagleboard.org/discuss >>>>> --- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "BeagleBoard" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected]. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> >>>> -- >>>> For more options, visit http://beagleboard.org/discuss >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "BeagleBoard" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >>> For more options, visit http://beagleboard.org/discuss >>> --- >>> You received this message because you are subscribed to a topic in the >>> Google Groups "BeagleBoard" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/beagleboard/Mef65w6PZ7s/unsubscribe. >>> To unsubscribe from this group and all its topics, send an email to >>> [email protected]. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> >> -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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