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From: -jg on 19 Dec 2009 16:31 On Dec 19, 11:00 pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: > > I'm looking at 8127C-AVR-10/09 and on page 28 I find that there is > "vcc monitoring" and a VLM circuit. But for gosh sake that darned > thing sucks power -- page 146, curve on the page's bottom. Cripes. No such thing as a free lunch ;) Such brownout monitoring is widely varying in uC, and some fudge things by sleeping the Monitor on a sub-uA timer. One caveat to those contemplating using a Micro as a Watchdog : WHO is watching your watchdog ? -jg
From: Jon Kirwan on 19 Dec 2009 16:48 On Sat, 19 Dec 2009 13:31:43 -0800 (PST), -jg <jim.granville(a)gmail.com> wrote: >On Dec 19, 11:00�pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: >> >> I'm looking at 8127C-AVR-10/09 and on page 28 I find that there is >> "vcc monitoring" and a VLM circuit. �But for gosh sake that darned >> thing sucks power -- page 146, curve on the page's bottom. �Cripes. > > No such thing as a free lunch ;) Especially true with this part. I don't recall _ever_ seeing that high of current requirement (at voltages I can compare across.) I think the PIC12's BOR is half that, or less. > Such brownout monitoring is widely varying in uC, and some fudge >things by sleeping the Monitor on a sub-uA timer. Would that be Microchip's XLP variety? (I haven't looked, but I remember reading way-too-good-to-be-true figures for the required current -- in tens of nanoamp range.) > One caveat to those contemplating using a Micro as a Watchdog : WHO >is watching your watchdog ? A lot of systems do little other than use the 'free' watchdog that comes with them. It's a little nicer to have something dedicated to the purpose on the outside of all that. And if you don't trust that or feel that cosmic rays might yield a false result, stack them four deep with one having one pin 'lifted' so it knows it is the monitoring one and use it to generate the voting result... maybe? ;) Jon
From: Leon on 20 Dec 2009 14:19 On 19 Dec, 21:48, Jon Kirwan <j...(a)infinitefactors.org> wrote: > On Sat, 19 Dec 2009 13:31:43 -0800 (PST), -jg > > <jim.granvi...(a)gmail.com> wrote: > >On Dec 19, 11:00 pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: > > >> I'm looking at 8127C-AVR-10/09 and on page 28 I find that there is > >> "vcc monitoring" and a VLM circuit. But for gosh sake that darned > >> thing sucks power -- page 146, curve on the page's bottom. Cripes. > > > No such thing as a free lunch ;) > > Especially true with this part. I don't recall _ever_ seeing that > high of current requirement (at voltages I can compare across.) I > think the PIC12's BOR is half that, or less. > > > Such brownout monitoring is widely varying in uC, and some fudge > >things by sleeping the Monitor on a sub-uA timer. > > Would that be Microchip's XLP variety? (I haven't looked, but I > remember reading way-too-good-to-be-true figures for the required > current -- in tens of nanoamp range.) They can achieve 20 nA, but the chip isn't actually much use for many applications in that mode. Leon
From: Jon Kirwan on 20 Dec 2009 18:40 On Sun, 20 Dec 2009 11:19:39 -0800 (PST), Leon <leon355(a)btinternet.com> wrote: >On 19 Dec, 21:48, Jon Kirwan <j...(a)infinitefactors.org> wrote: >> On Sat, 19 Dec 2009 13:31:43 -0800 (PST), -jg >> >> <jim.granvi...(a)gmail.com> wrote: >> >On Dec 19, 11:00�pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: >> >> >> I'm looking at 8127C-AVR-10/09 and on page 28 I find that there is >> >> "vcc monitoring" and a VLM circuit. �But for gosh sake that darned >> >> thing sucks power -- page 146, curve on the page's bottom. �Cripes. >> >> > No such thing as a free lunch ;) >> >> Especially true with this part. �I don't recall _ever_ seeing that >> high of current requirement (at voltages I can compare across.) �I >> think the PIC12's BOR is half that, or less. >> >> > Such brownout monitoring is widely varying in uC, and some fudge >> >things by sleeping the Monitor on a sub-uA timer. >> >> Would that be Microchip's XLP variety? �(I haven't looked, but I >> remember reading way-too-good-to-be-true figures for the required >> current -- in tens of nanoamp range.) > >They can achieve 20 nA, but the chip isn't actually much use for many >applications in that mode. At what current level do they become useful? Jon
From: Leon on 21 Dec 2009 14:18
On 20 Dec, 23:40, Jon Kirwan <j...(a)infinitefactors.org> wrote: > On Sun, 20 Dec 2009 11:19:39 -0800 (PST), Leon > > > > <leon...(a)btinternet.com> wrote: > >On 19 Dec, 21:48, Jon Kirwan <j...(a)infinitefactors.org> wrote: > >> On Sat, 19 Dec 2009 13:31:43 -0800 (PST), -jg > > >> <jim.granvi...(a)gmail.com> wrote: > >> >On Dec 19, 11:00 pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: > > >> >> I'm looking at 8127C-AVR-10/09 and on page 28 I find that there is > >> >> "vcc monitoring" and a VLM circuit. But for gosh sake that darned > >> >> thing sucks power -- page 146, curve on the page's bottom. Cripes. > > >> > No such thing as a free lunch ;) > > >> Especially true with this part. I don't recall _ever_ seeing that > >> high of current requirement (at voltages I can compare across.) I > >> think the PIC12's BOR is half that, or less. > > >> > Such brownout monitoring is widely varying in uC, and some fudge > >> >things by sleeping the Monitor on a sub-uA timer. > > >> Would that be Microchip's XLP variety? (I haven't looked, but I > >> remember reading way-too-good-to-be-true figures for the required > >> current -- in tens of nanoamp range.) > > >They can achieve 20 nA, but the chip isn't actually much use for many > >applications in that mode. > > At what current level do they become useful? > > Jon They retain the RAM contents at 25 nA, typically, which is some use. RAM contents are lost at 20 nA. They take 500 nA with the RTC and calendar operational. Leon |