Hi, I am trying to use this code with an Adsong dht22 (am2302) temp/rh sensor running on the BBB. I haven't used C for a number of years so I am kind of rusty. What modifications did you make to compile it with g++ on the BBB? How does portG map to the pinout on the BBB? Or what pin do I connect the data line to on the BBB?
Thanks! On Tuesday, October 8, 2013 11:06:43 AM UTC-4, Lloyd Bailey wrote: > > You can modify this code http://www.acmesystems.it/?id=89 > > I have and it works on my Beaglebone black. :) > > On Wednesday, 28 August 2013 04:25:30 UTC+1, CJNZ wrote: >> >> Hi Hunyue, >> >> I am trying to get the SHT15 working on a classic Beagle. >> I realise this is an old thread, but I am struggling a bit with the code. >> Do you still have a code example that you could share? >> Did you just connect clock and data to standard GPIO and 3.3 and ground? >> >> Thanks, >> CJ >> >> On Tuesday, October 16, 2012 7:41:20 PM UTC+13, H wrote: >>> >>> On Mon October 15 2012 19:08:51 Aaron Patterson wrote: >>> > On Mon, Oct 15, 2012 at 4:58 PM, Dan Watts >>> <[email protected]> wrote: >>> > > Hi, >>> > > >>> > > You're right: the Adafruit code does look odd. >>> > > >>> > > As you say, to initiate communication with the DHT11/DHT22, >>> > > you're supposed to pull the signal low for > 18 ms, then >>> > > high, then wait for the signal to be pulled low again. >>> > > Their code appears to skip the pull-high part. I can only >>> > > assume that the Pi stops pulling the signal low when it >>> > > switches to input mode. >>> > > >>> > > The only possible problem I can see in your code is that you >>> > > might not be pulling the signal low for long enough: perhaps >>> > > the usleep(2000) should be usleep(20000)? Also, trying to >>> > > catch that 40 microsecond signal that begins the DHT22's >>> > > response is tricky - that's probably why the Pi's code >>> > > doesn't pull the line high explicitly. Perhaps dropping the >>> > > digitalWrite(HIGH) from your code would have the same >>> > > effect? >>> > >>> > I gave both of these a whirl, and they did not work. I am >>> > able to see the signal on my oscilloscope, though I'm new to >>> > using the oscilloscope, so I'm not 100% sure. >>> > >>> > > I have my doubts about whether reading data from the DHT22 >>> > > can work reliably from Linux code, given the tight timing >>> > > involved. Apparently the Adafruit code is managing to do it >>> > > on the Pi, but there is a warning at the beginning of their >>> > > tutorial saying it may not work, and perhaps the library >>> > > they are using is more optimized than what is available for >>> > > the Bone. >>> > >>> > Yes, I read that. I'm starting to have the same doubts as >>> > well. >>> > >>> > > Personally, I wimped out and use a separate processor to >>> > > read the DHT22. I actually use a .Net Micro Framework >>> > > processor for this (which surprisingly is able to handle the >>> > > timings) and serial I/O, but something like the ATTiny2313 >>> > > and I2C would be a better design. >>> > >>> > I'm starting to think I might need to do the same. I'll give >>> > the Pi a try, and I've got an Electric Imp on the way, so >>> > I'll probably try it too. >>> >>> >>> That would appear to be an overkill to toss in another processor. >>> Prehaps a different part would be more appropriate? >>> >>> FWIW, I recently got a humidity sensor working on the classic >>> Beagle. This is the SHT-15 part. Everything pretty much was drop >>> in. Hookup. The setup was: >>> >>> SHT-15 - <Level Converter, 3.3V source> - Beagle Classic. >>> >>> Driver for it was all upstream. It is built on top of the GPIO >>> subsystem. The level converter and 3.3V are option on the >>> beaglelcd board. Write up for it will be posted as time permits. >>> >>> Since IO on the bone is 3.3V, the level converter won't be >>> needed. >>> >>> > >>> > I've built a meat curing fridge, and I'm trying to build an >>> > internet enabled controller. I've built a monitor for it >>> > using the TI Launchpad, and I'd like to build something that >>> > will post the information to the internet (without hooking up >>> > to my laptop and reading from a TTY). I suppose I could try >>> > XBee, but everything seems much harder since I'm not using an >>> > Arduino. :-( >>> > >>> > Anyway, thanks for the response. If I can't get the Pi or the >>> > Imp to work out, I'll hook the Launchpad up to the Bone via >>> > UART. >>> > >>> > Again, thanks for your time. I appreciate the response! >>> > >>> >>> -- >>> Hunyue Yau >>> http://www.hy-research.com/ >>> >> -- 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/groups/opt_out.
