I have a few thoughts on this. First, I would love to see a model for DAC as well as PWM for output. A simple two double byte model with a 16 bit set for signed output and 16 bits for log gain. Clearly there is nothing that you are going to hook to a 1-wire bus that is capable of this kind of precision and it may even be fixed gain, but it costs almost nothing to build a common structure that this class can do. 2-10V/4-20ma is such a common control point model that this kind of capability would be quite useful for things like HVAC damper positioning.
[Depending on the reliability and cost per point, I could be interested in buying some of these as well. Same goes for precise thermocouple inputs.] I liked Pascal's simple model for frequency and duty cycle for PWM. I have a minor concern that the frequency side is designed around one implementation, so I would like others thinking about PWM to see if we need a more general model for frequency side. Second, I would propose the use of a classic open source model for those who want to play together. When someone comes up with a new area of functionality, they can sketch up a common I/O structure. Then others who have similar interest can join in and come up with a general model that works for a given class. Using PWM as an example, we may end up with a simple model to start with and a more complex model down the road. I see that as OK as long as the code maintenance doesn't turn into a trove of dead ends. Now that we are stepping into this world of programmable 1-wire devices, there is the problem of discovery. How can we well what capabilities are available from a given serial number? Here is a modest proposal that would seem to fit the overall model of the system. Since synthesized read address space is cheap on these beasts, perhaps we can have something that has a given read only address block that 1-wire can read and see what standard options the device has and how many of them are implemented on a given board. If this block also gave the address offset of where to control the block, then the 1-wire code can stay fairly stupid in granular implementation. We end up with some representation details like how do you expose 4 PWMs under a single address. I worry less about these since I tend toward programatic control rather than web based. With this, we are getting close to my dream. That has something like a zigbee mote with a small chain of fixed and programmable 1-wire devices. Add a battery/charger/power supply and a redundancy model and you have something that is small, cheap and could rival almost anything available. The mote handles simple local control and emergency shutdown. The rest happens up the food chain. warmly, jerry tmk wrote: > I am writing a 1 wire slave library for the AVR series of > microcontrollers. > > That should allow you to do all the stuff you want. > > Hooking into OWFS might be a little tricky if everyone implements > their own functionality though. > > If a standard set of functionalities can be agreed on, (counter, pwm, > tri state pio, temp sensor, ADC, memory access), then almost anything > could be done > > Anyone have other suggestions for functionality? > > I figure that should cover most cases, and other stuff could be done > with the memory access. In fact I will most likely implement it all > with memory commands. > > Off topic: > I have also considered making a complete clone of the DS2490 (usb to 1 > wire master) on an AVR chip. $30 is too much for a USB -> 1wire adapter! > > An ATTiny chip should be able to handle it no problem > > Would this be interesting? Is there a datasheet on the 2490 usb > interface? Owfs supports it, so I should be able to get what I need > from the source code, worst case > > -tmk > > On Feb 22, 2010, at 7:38 AM, Benjamin Donnachie <benja...@py- > soft.co.uk> wrote: > >> On 22 February 2010 15:22, Pascal Baerten <pascal.baer...@gmail.com> >> wrote: >>> But if for any reason I would stop this activity, I will pass the >>> relay to >>> someone else, or even open source the project... >> I'm a newcomer to 1-wire and was a bit disappointed to see the DS2423 >> phased out and joined this list to discuss the practicalities of >> building a counter replacement from a simple PIC. However, BAE0910 >> seems to be an excellent alternative and I'm hoping to order the board >> shortly. >> >> However, I'd be interested to know whether there is any interest in a >> simple open-source PIC-based counting device? Has anyone tried this >> approach already? >> >> Take care, >> >> Ben >> >> --- >> --- >> --- >> --------------------------------------------------------------------- >> Download Intel® Parallel Studio Eval >> Try the new software tools for yourself. Speed compiling, find bugs >> proactively, and fine-tune applications for parallel performance. >> See why Intel Parallel Studio got high marks during beta. >> http://p.sf.net/sfu/intel-sw-dev >> _______________________________________________ >> Owfs-developers mailing list >> Owfs-developers@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/owfs-developers > > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intel-sw-dev > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
