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.
