My HGI80 equivalent Domoticz setup without HGI80

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  • dty
    Automated Home Ninja
    • Aug 2016
    • 489

    My HGI80 equivalent Domoticz setup without HGI80

    Hello,

    Several people have asked me recently (in threads, and via PM) about my Domoticz setup which is equivalent to using an HGI80, but without the HGI80!

    I intend to write more about it soon, but in summary I use a Raspberry Pi which has a radio board I bought from busware.de (I'll write more about this too). The radio board has an Atmel atmega1284p microcontroller and a Texas Instruments CC1100 radio chip on it. I have custom-written firmware which runs on the microcontroller and configures and interfaces with the radio chip to read the Evohome radio messages and decode them into the same format that the HGI80 produces. At this point, Domoticz thinks it's talking directly to a genuine HGI80 and everything is good! (Oh, and it can transmit too, so you have rudimentary control of the Evohome via Domoticz.)

    I am a professional software developer, and the code I hacked together is somewhat shameful. I'm in the process of cleaning it up, etc., and will publish it here together with more information when I'm done.

    If anyone has any questions in the mean time, please feel free to ask!
  • MrB
    Automated Home Sr Member
    • Oct 2015
    • 80

    #2
    Thanks for this @dty.

    We all have "dirty" code as it's for us and not for a commercial product/team
    I'm sure everybody who would like to use it would only be too happy to help with cleaning/improving it.

    Looking forward to the detail.

    Comment

    • DBMandrake
      Automated Home Legend
      • Sep 2014
      • 2361

      #3
      Watching with interest...

      Comment

      • DanD
        Automated Home Ninja
        • Feb 2016
        • 250

        #4
        @dty

        Thanks for posting the details on this. I'm beginning to think that this may ultimately prove to be a better solution for those interested in using Domoticz to analyse and control their Evohome system. My reason for saying this is that I'm currently testing repeater functionality using the HGI80 and it's taken me some time (and significant frustration) to discover and fully understand what others have posted previously, that the HGI80 always inserts its fixed device type and ID (18:730) when sending messages. I'm not yet sure whether this will prevent successful implementation of the HGI80 as a repeater, as my testing is now going OK, but it's certainly added further complexity to my development.

        I might need to be building my own device soon!

        Dan

        Comment

        • StuartP
          Moderator
          • Feb 2004
          • 81

          #5
          I'm going to echo comments of others here, more than happy to take a look at 'dirty' code.

          Are the resource requirements such that the code will only run on as 1284p, or is the code footprint small enough that it would run on a smaller processor ?

          Comment

          • dty
            Automated Home Ninja
            • Aug 2016
            • 489

            #6
            @DanD - I'd like to explore a repeater. I'm increasingly convinced that the only sensible way to do it is for the repeater to pretend to be a controller and have the "far away" devices "bind" to it, and then have it do a pretend binding to the real controller so that it can store and (re-address and) forward messages as necessary. I'm not sure simply receiving and re-broadcasting will work. I suspect it will confuse some devices and you'll definitely end up getting collisions - when a device makes a request from the controller, for example, and the controller responds at the same time as your repeater is re-broadcasting. And I don't think a simple delay will work, because there's only a relatively narrow window when the battery-operated devices are awake listening to transmissions, and if you're not careful your delayed re-transmission will miss that window.

            @MrB - there's dirty and there's destroy your professional reputation :-)

            @StuartP - I honestly don't know. I don't think it's super heavyweight, but it does need to be able to synchronously clock-in serial data at 38400 baud. Even at 8MHz, that only gives you about 200 clock cycles per bit. You're going to struggle with anything slower than 8MHz. To be fair, the board manufacturers have sadly not linked up the CC1100 to the Atmel's UART pins, so I've had to build a software UART. If they had, I think things would be nicer because I'd just program the UART and get raw bytes from the radio. Also, the CC1100 is capable of doing packet handling, but it's not configurable enough to allow it to interpret the Rameses II protocol in hardware. So I end up synchronously reading raw bits (not bytes) from the radio and doing all the packet handling (preamble, start/stop bits, etc.) in software.

            I'm increasingly warming to the idea of ditching the controller and writing my own one! That way I could build in repeaters, unlimited zones, etc.

            Comment

            • orange
              Automated Home Guru
              • Dec 2014
              • 149

              #7
              just chiming in to say that you can get a HGI80 via ebay for not much more than it costs to roll your own - the ebay seller I used had an "offer" function so don't be mislead by the advertised price

              Comment

              • DBMandrake
                Automated Home Legend
                • Sep 2014
                • 2361

                #8
                I was following one on ebay a few weeks ago and it ended up going for about £70 and I could have got it but decided to pull out of the bidding in the last few minutes when it went over £60 as I didn't really have the money to spend and only wanted it if it was a real bargain!

                Comment

                • orange
                  Automated Home Guru
                  • Dec 2014
                  • 149

                  #9
                  paid 95 euro for this

                  Find many great new & used options and get the best deals for Honeywell HGI 80 Gateway Interface HGI80 at the best online prices at eBay! Free delivery for many products!


                  possibly I could have offered lower. Just arrived, shipping only took 2 days from purchase

                  (sorry for thread hijack !)

                  Comment

                  • clarkie
                    Automated Home Jr Member
                    • Jan 2017
                    • 11

                    #10
                    Hi is this the radio module from busware.de

                    Comment

                    • dty
                      Automated Home Ninja
                      • Aug 2016
                      • 489

                      #11
                      Yes. You'll need an antenna to go with it. I use this one: "Antenna RP-SMA +3dBi 5cm"

                      I'd upload a picture, but for some reason the forum software isn't letting me. The Pi no longer fits in the standard case, so it would need some alternative enclosure (I'm thinking of using a margarine tub and just hiding the whole lot away somewhere!) or some modifications to the standard case.

                      Comment

                      • DanD
                        Automated Home Ninja
                        • Feb 2016
                        • 250

                        #12
                        I've decided to go the 'homebrew' route too, but I'm going to try an RFBee with a UartSBee. I plan to initially use it to help troubleshoot some difficulties I'm having with my Evohome Domoticz development. I hope to also be able to finalise some additional Domoticz features which I've not been able to successfully implement with the HGI80.

                        Comment

                        • dty
                          Automated Home Ninja
                          • Aug 2016
                          • 489

                          #13
                          As far as I can make out, the RFBee is similar to the SCC in that it combines an Atmel MCU and a TI CC1101 on one board. I've read that the UartSBee can cause problems for a Raspberry Pi. Something to do with the number of interrupts it, or the driver, generate. But you have the advantage that you can plug into something other than a Raspberry Pi which you can't with my solution.

                          Comment

                          • dty
                            Automated Home Ninja
                            • Aug 2016
                            • 489

                            #14
                            By the way, I'm very close to getting OpenTherm if that's helpful for you?

                            Comment

                            • DanD
                              Automated Home Ninja
                              • Feb 2016
                              • 250

                              #15
                              @dty

                              Thanks for all the info. The opentherm bridge is on my Domoticz to-do list, so let me know when you're set-up. I've got some logging info from a couple of users, but some more data will help. I think I'm going to focus on fixing the implementation of a couple of the Honeywell devices (opentherm bridge, underfloor controller and the T87 thermostat) whilst I'm waiting for the RFBee stuff.

                              Dan

                              Comment

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