Date: Thu, 21 Aug 2014 15:44:36 -0300 From: Evandro Nunes <evandronunes12@gmail.com> To: Rui Paulo <rpaulo@freebsd.org>, freebsd-arm@freebsd.org Subject: Re: HC-SR04 and FreeBSD Message-ID: <CAG4HiT6YUBCxXrK_KyRW6zTthPa-wDe=A9=CmMHQf-Gh54s7QA@mail.gmail.com> In-Reply-To: <CCD5AEE5-798D-4EAC-BAE7-A086DE55B5D2@FreeBSD.org> References: <CAG4HiT6wwbmSA_KWsgHOqdeZVOCUsdhRxDhMubvkG1tEwVH5Sw@mail.gmail.com> <5D802942-2D0F-4324-8212-C2871EEB6327@FreeBSD.org> <CAG4HiT6fiqVXMoqcJra1Yh8aFVbOcezP8rRqst6WC8aHuaF_rA@mail.gmail.com> <01562FB1-32C6-45AF-AB77-5BB80526E18C@FreeBSD.org> <CAG4HiT4kKz18iauXfuF0Dpv-USghunssUvwkTF7bDx_gE_VS2w@mail.gmail.com> <CCD5AEE5-798D-4EAC-BAE7-A086DE55B5D2@FreeBSD.org>
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On Thu, Aug 21, 2014 at 1:24 PM, Rui Paulo <rpaulo@freebsd.org> wrote: > On Aug 20, 2014, at 22:34, Evandro Nunes <evandronunes12@gmail.com> wrote: > > > On Thu, Aug 21, 2014 at 2:05 AM, Rui Paulo <rpaulo@freebsd.org> wrote: > > On Aug 20, 2014, at 21:52, Evandro Nunes <evandronunes12@gmail.com> > wrote: > > > > > On Thu, Aug 21, 2014 at 1:51 AM, Rui Paulo <rpaulo@freebsd.org> wrote: > > > On Aug 20, 2014, at 21:48, Evandro Nunes <evandronunes12@gmail.com> > wrote: > > > > > > > hello, > > > > > > > > ive got a ultrasonic sensor model HC-SR04 and a beaglebone black as > well as > > > > a cubieboard2, both running FreeBSD 11 built from crochet and wiki > > > > instructions > > > > > > > > thanks to the help from loos@ I could manage to use a 5v relay with > BBB > > > > now, how can I read data from HC-SR04 sensor? do we have any library > > > > available? or do we have any GPIO utility to do that? > > > > btw how can I read values from GPIO pins when they are set to input? > > > > > > I wrote a library to handle GPIO on FreeBSD: > > > > > > https://bitbucket.org/rpaulo/libgpio > > > > > > very good :-) I will play with that > > > > > > You can also use the gpioctl utility in FreeBSD to read values. > > > > > > how? can you point me to any further reading, blog entry, or examples? > > > > There's a man page, but "gpioctl -c <PIN> IN" will set the pin in input > mode. Then, "gpioctl <PIN>" will read the value. > > > > so this way I should read something from HC-SR04 echo pin on BBB? > > I am using another gpio pin in output mode as a trigger, according to > what I've read, 3.3v is OK as a trigger for this sonar > > > > but when I read the GPIO pin in input mode just as you mentioned, I > always get a 0 value... > > I am using BBB's P9_1 and P9_5 for +5v and ground, P9_21 as a trigger > and P9_23 as echo; set GPIO 3 (P9_21) as output and GPIO 49 (P9_23) as input > > I made a loop to read GPIO 49 every 100ms and another loop to trigger > (gpioctl -t 3; sleep .100; gpioctl -t 3) every 2 seconds. > > > > what I am doing wrong? feeding 3.3v for 0.1 seconds as a trigger > should't cause something to echo? > > Don't you have a multimeter? Have you measured the voltage on the output > pin when you switch it to 0 and then back to 1? > no, I don't have a working multimeter, mine is dead. I will buy another one and test it as suggested, yes you are right, although I dont have an idea on what value it should be expected but for curiosity, will gpioctl 49 show values anyhow equivalent to what a multimeter would display? or I should not expect anything similar? sorry for that question if this is too dummy, yes I completely lack on GPIO basics, it's my first experience rss > -- > Rui Paulo > > > >
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