On 4/28/14 15:45 , Johan Ström wrote: > On 4/28/14 15:29 , Jan Kandziora wrote: >> Am 28.04.2014 13:50, schrieb Johan Ström: >>> Mostly this has been working good, with reliable triggering of the >>> latch. However, one problem with pull-up based circuit is that I get >>> erroneous triggers if VCC disappears, for example due to a bus >>> disconnect, >> With a DS2408, I would always check the POR flag and sort out errorneous >> latch states in the software. >> >> With a DS2406, there isn't such a POR flag, but you can check the status >> byte 7 whether it is in factory setting. That would mean POR. This only >> works when you don't use the correspoding setting "Respond to >> conditional search when PIO A or B is high". > Hi, thanks for your input! > > I employ that scheme as well. In owfs terms, this means reading the > (uncached) set_alarm property and verifying that the settings are indeed > what I expect. Which by the way is 111 for single-input DS2406. > (channel A activity latch is 1). For dual-input I use 311.
A small elaboration regarding the above and my earlier thoughts on pull-down vs pull-up: When the DS2406 is parasite powered (for example single-input device, with no posibillity to connect VCC), a break on the VCC line (but not 1W/GND) would not be seen by looking for altered alarm flags. Instead, the pull-up would just disappeared, with high risk of triggering of the latch. Hence my pull-down scheme instead. Regards Johan ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available. Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
