Like Sumukh, I haven't heard this problem could be encountered with software. Also discrete comparators typically consume few hundred microamps plus the reference you need for them. Often designers just put a supervisor chip of suitable voltage range on processors reset line and ignore the issue.
TI itself has put out some new open collector supervisor chips on SOT-23 package, and the funny thing is that there stands on the feature list the following: "Applications Include .. * Applications Using the MSP430" There are several manufacturers around that make high class supervisor chips. Regards, Matti Ruusunen ----- Original Message ----- From: "Sumukh Pathare" <sumukh_path...@yahoo.com> To: <mspgcc-users@lists.sourceforge.net> Sent: Friday, August 22, 2003 8:21 PM Subject: Re: [Mspgcc-users] Brown out reset > As far as I know there isn't a software solution for > this. The uC is not really functioning so the WDT will > not kick in an reset. The problem is worse if you have > large value electrolytic caps. They take a long time > to discharge. > Best way is to use a device which resets the uC if the > voltage goes out of certain tolerance. I have used > TPS79733 with good results. It has a open drain PG > (power good signal). You can connect it to RST\ pin of > the uC (with a pull up resistor to Vcc) > > -Sumukh > > > --- Tom Russell <tcruss...@mail.com> wrote: > > have a circuit with the MSP430F133 that needs > > brown-out reset. If the > > power is disconnected for a short time, but not long > > enough for the voltage > > to decay to near-zero, I don't get a POR when power > > returns and the program > > goes to an unknown state. I could monitor the > > voltage and when it gets low > > generate a POR by pulling RST low or a PUC by > > writing an exception to the > > WDT. The problem is that the unit will then > > continue to operate from that > > point until the voltage falls low enough to mess it > > up and then I still > > don't think I can be sure what happens when power is > > restored. I don't > > think using the comparator helps because its control > > register will also > > become undefined as the voltage drops. > > > > Of course I can add an external voltage comparator > > connected to the reset > > pin, but anyone have a software solution? I know > > some MSP parts have BOR > > (brown-out reset), but strangely not all. > > > > Thanks for any suggestions, > > > > Tom Russell > > > > > > > > > > > ------------------------------------------------------- > > This SF.net email is sponsored by: VM Ware > > With VMware you can run multiple operating systems > > on a single machine. > > WITHOUT REBOOTING! Mix Linux / Windows / Novell > > virtual machines > > at the same time. Free trial click > > here:http://www.vmware.com/wl/offer/358/0 > > _______________________________________________ > > Mspgcc-users mailing list > > Mspgcc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/mspgcc-users > > > __________________________________ > Do you Yahoo!? > Yahoo! SiteBuilder - Free, easy-to-use web site design software > http://sitebuilder.yahoo.com > > > ------------------------------------------------------- > This SF.net email is sponsored by: VM Ware > With VMware you can run multiple operating systems on a single machine. > WITHOUT REBOOTING! Mix Linux / Windows / Novell virtual machines > at the same time. Free trial click here:http://www.vmware.com/wl/offer/358/0 > _______________________________________________ > Mspgcc-users mailing list > Mspgcc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/mspgcc-users
