Ok, the SRAM will be lost BUT for do you really want to keep logged data in SRAM for an extended period. It's safer to just store is on completeion of one session... Mike Keitz wrote: > > On Fri, 28 May 1999 12:42:18 +1000 Antonio L Benci > writes: > >Here's a suggestion. Now i don't know what the operating current for > >these devices is BUT how about powering up the flash memory from a > >PORT > >pin. The 16F84 can supply up to 20mA/pin. When not being accessed the > >port pin is set LOW, no power is consumed. > > Overall it's not a bad idea. For an application that is mostly or > exclusively reading it would be ideal. But when the power is cut off, > the data in the SRAM part of the flash chip will be lost too. So if the > PIC doesn't have enough SRAM to hold up to a whole block of data before > moving it to flash, there is a problem. > > It would be possible to write less than a full block at a time by reading > a block from flash into the SRAM, adding a few bytes of new data, then > storing it back to the same block of flash before turning the power off. > But the extra write cycles will probably use more power than just leaving > the flash chip in standby and holding the partial block in the SRAM. To reduce the write cycles the software would only write once a complete block is ready... This would mean that it may be some time for a complete block to be ready but once it is so then store and turn off... > > ___________________________________________________________________ > You don't need to buy Internet access to use free Internet e-mail. > Get completely free e-mail from Juno at http://www.juno.com/getjuno.html > or call Juno at (800) 654-JUNO [654-5866] -- ****************************************************** * Antonio (Nino) Benci * * Electronic Services Manager * * Monash University - Dept of Physics * * Wellington Rd, Clayton. 3168 * * Victoria, Australia. * * TEL - 61 3 9905 3649, FAX - 61 3 9905 3637 * * Mobile - 0414 764 763 (private and ah only) * * EMAIL - nino.benci@sci.monash.edu.au (work) * * - fleatech@excite.com (private) * * WWW - www.physics.monash.edu.au/ * ******************************************************