2 Replies Latest reply on Apr 19, 2017 2:46 PM by Intel Corporation

    DHT11 on Edison with Python mraa

    onegrx

      Hi guys,

       

      Could you please take a look at the question I've recently posted on SO regarding problems with DHT11: python - DHT11 sensor failure on Edison whereas working successful on RPi - Stack Overflow

       

      I read some threads here about one-wire devices workaround but I don't fully understand it and maybe do something wrong. Furthermore, nobody ever experienced those IN/OUT switching port problems on RPi. It is also a genuine computer system with real time OS, isn't it?

       

      Thank you in advance,

      Bart

        • 1. Re: DHT11 on Edison with Python mraa
          SpiderKenny

          The 1-Wire protocol, as you know, requires deterministic timing. It is not possible to do deterministic timing on a computing platform like Edison, or even a PC. You might get somewhere close to it using usleep() but your app may get interrupted at any time, thereby messing up your timings.

          What you need to do when using a system without deterministic timing of GPIO is attach the sensor using an interface. That interface should use a small micro which DOES have deterministic timing. (ie a Pic, ATTINY, etc).

          • OR - Use an existing peripheral on your system which does have deterministic timing, such as a UART.

          I wrote a blog-post some years ago on how you can use a UART to do 1-Wire protocol. You should be able to find it here: http://wphost.spider-e.com/?p=231

          • 2. Re: DHT11 on Edison with Python mraa
            Intel Corporation
            This message was posted on behalf of Intel Corporation

            Hi guys,

            First, I want to say thanks to SpiderKenny, we really appreciate your help in the community. And Bart, I recommend you to try SpiderKenny’s suggestions, in case you need more information take a look at this thread created by SpiderKenny: https://communities.intel.com/thread/55975

            I hope you consider this useful.

            Regards,
            Leonardo R.