Hi Jens, I know you can make things in 1,000 different ways but in the end, it is powered by a battery which basically means your solution cannot use more than say 5uA average current. There is not a lot you can do with that :-) And secondly, the ideal solution would preferably fit within 1 cubic mm :-).
Michel On Apr 21, 9:01 pm, jb-electronics <[email protected]> wrote: > Hi Michel, > > you are right, I did not assume it was so complicated. However, have you > considered using frequency modulation of the IR signal? This way you > could easily subtract daylight digitally. > > Jens > > > > > > > > > It really is a bit more complicated than that Jens. I generate a very > > short but very strong IR pulse, I'd have to check the exact numbers > > but it is somewhere around 250mA for 2 or 3 usec. The IR light > > reflects from an object above the watch (a hand for example) onto an > > IR photodiode. To make this work in all situations, the photodiode > > should not saturate when there's a lot of light around (say you are > > outside in the sunshine), so it's series resistor is relatively low > > (which also helps making it very fast) and the signal received from > > the powerful 250mA pulse is only like 40mV. > > > I first built that with some gates, capacitors and resistors. It > > worked very well but used about 400uA average current if I am not > > mistaken. > > > 10uA is pretty much what it should be according to the data sheets if > > you add up all the currents. Honestly, a battery will last for ages > > (about 8 years) with a 10uA load, so I am really not worried about > > that. It's just that the processor supports deep sleep mode, so I'd > > like to incorporate that as well > > > Michel > > > On Apr 21, 7:59 pm, jb-electronics<[email protected]> > > wrote: > >> Hello Michel, > > >>> Problem is that I need more components to be able to generate the > >>> interrupt > >> I would have used simple diodes that are OR'ed together to the external > >> interrupt pin. > > >>> and believe it or not, it actually used more current. > >> Actually, I don't see that happening with diodes, do you? OK, if your > >> sources have different voltage levels you need shifters and these > >> require current, of course. > > >>> Standby mode means the processor is in sleep mode but wakes up about 8 > >>> times per second to check the sensor. The sensor only uses 2uA but the > >>> processor uses more current in sleep than in deep sleep mode, so all > >>> together it is 10uA. > >> Have you played around with the configuration bits? I once realised that > >> a silly enabled Brown-Out detect (which makes no sense with > >> battery-powered devices) takes up almost all the current. > > >> Sorry if this has been mentioned before, but which processor do you use? > > >> Best regards, > >> Jens > > >>> In deep sleep, the processor is completely powered down, only the RTCC > >>> continues running. It can only be awakened by an external interrupt > >>> (push button rather than motion sensor). > >>> Michel > >>> On Apr 21, 7:23 am, jb-electronics<[email protected]> > >>> wrote: > >>>> Looks very good! > >>>>> Total circuit power is about 10uA during standby mode and 2uA during > >>>>> deep sleep. > >>>>> Deep sleep will be entered after a standby time-out to save battery > >>>>> life. Clock will still run in deep-sleep mode. > >>>> I am curious: Do you use an external interrupt to wake the processor in > >>>> case of a motion etc? This might be useful and could avoid the "standby > >>>> mode" altogether. > >>>> Jens -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
