Low Voltage Reset - Voltage Regulator for BX-35

Started by Art Church May 5, 2005
Do I need to have a low voltage reset chip for the BX-35 ?
I dont see one in the suggested hookup but it just show VCC
http://www.basicx.com/Products/BX-35/BX35_Schematic.gif

There is one for the reccomended hookup for the siteplayer ( I think reset is to take the line high) vs the BX to low

Also could I supply both the siteplayer and the bx-35 chip with the same voltage regulator supply - the siteplayer shows a little different filtering but adding that will not affect the BX-35 I dont think.

Could I use a low voltage drop out regulator for the BX-35 ? Thanks
Art


> ... Do I need to have a low voltage reset chip for the BX-35

No, it's built-in. From page 19 of the Atmel AT90S8535 dox:

"Reset Sources:
The AT90S4434/8535 has three sources of reset:
. Power-On Reset. The MCU is reset when the supply voltage is below the
power-on reset threshold (VPOT)..." Tom
Tom Becker
--... ...--
GTBecker@GTBe... www.RighTime.com
The RighTime Clock Company, Inc., Cape Coral, Florida USA
+1239 540 5700



Art,

I decided that the VPOT threshold was too low so I use an integrated
reset button and DS1232 power monitor chip on my BX-35 Development Board
(http://home.austin.rr.com/perks/basicx/DevelopmentBoard.htm). The
schematic for that part of the circuit is shown here:
http://home.austin.rr.com/perks/basicx/DevelopmentBoard/BrownOut.JPG.

I think the wires XTAL2, /RST and jumper JP8 are self-explanatary.

Mike

> > ... Do I need to have a low voltage reset chip for the BX-35
>
> No, it's built-in. From page 19 of the Atmel AT90S8535 dox:
>
> "Reset Sources:
> The AT90S4434/8535 has three sources of reset:
> . Power-On Reset. The MCU is reset when the supply voltage is below the
> power-on reset threshold (VPOT)..." > Tom >
> Tom Becker
> --... ...--
> GTBecker@GTBe... www.RighTime.com
> The RighTime Clock Company, Inc., Cape Coral, Florida USA
> +1239 540 5700
>



I forgot to mention, I use the same reset line to reset a PIC LCD driver
chip from Peter Anderson and the DS1232 has both RESET and /RESET
outputs so you can use pin 5 to reset siteplayer. The low voltage
detection is configurable to either 4.5V or 4.75V. See the datasheet:
http://pdfserv.maxim-ic.com/en/ds/DS1232.pdf

Yahoo messed up the link in the attached append. You need to remove the
period or simply use this one instead:
http://home.austin.rr.com/perks/basicx/DevelopmentBoard/BrownOut.JPG

Mike

> Art,
>
> I decided that the VPOT threshold was too low so I use an integrated
> reset button and DS1232 power monitor chip on my BX-35 Development Board
> (http://home.austin.rr.com/perks/basicx/DevelopmentBoard.htm).
> <http://home.austin.rr.com/perks/basicx/DevelopmentBoard.htm%29.> The
> schematic for that part of the circuit is shown here:
> http://home.austin.rr.com/perks/basicx/DevelopmentBoard/BrownOut.JPG.
>
> I think the wires XTAL2, /RST and jumper JP8 are self-explanatary.
>
> Mike
>
> > > ... Do I need to have a low voltage reset chip for the BX-35
> >
> > No, it's built-in. From page 19 of the Atmel AT90S8535 dox:
> >
> > "Reset Sources:
> > The AT90S4434/8535 has three sources of reset:
> > . Power-On Reset. The MCU is reset when the supply voltage is below the
> > power-on reset threshold (VPOT)..."
> >
> >
> > Tom
> >
> >
> >
> > Tom Becker
> > --... ...--
> > GTBecker@GTBe... www.RighTime.com
> > The RighTime Clock Company, Inc., Cape Coral, Florida USA
> > +1239 540 5700
> >


--- In basicx@basi..., "Tom Becker" <gtbecker@r...> wrote:
> > ... Do I need to have a low voltage reset chip for the BX-35
>
> No, it's built-in. From page 19 of the Atmel AT90S8535 dox:

You'll note that the schematic for the earlier BX-24 shows a regulator
chip that resets the AT90S8535 when the regulator drops out. The
mega8535 has built-in brown out detection so the external circuitry is
no longer needed.



> ... shows a regulator chip that resets the AT90S8535 when the
regulator drops out.

You're right. The LP2951 will produce its ERR status (and thus a system
reset) earlier, at 4.75v. Tom
Tom Becker
--... ...--
GTBecker@GTBe... www.RighTime.com
The RighTime Clock Company, Inc., Cape Coral, Florida USA
+1239 540 5700


Thanks .. that helps a lot.
Art

> -----Original Message-----
> From: Mike Perks [SMTP:basicx@basi...]
> Sent: Thursday, May 05, 2005 11:44 AM
> To: basicx@basi...
> Subject: Re: [BasicX] Low Voltage Reset - Voltage Regulator for BX-35
>
> I forgot to mention, I use the same reset line to reset a PIC LCD driver
> chip from Peter Anderson and the DS1232 has both RESET and /RESET
> outputs so you can use pin 5 to reset siteplayer. The low voltage
> detection is configurable to either 4.5V or 4.75V. See the datasheet:
> http://pdfserv.maxim-ic.com/en/ds/DS1232.pdf
>
> Yahoo messed up the link in the attached append. You need to remove the
> period or simply use this one instead:
> http://home.austin.rr.com/perks/basicx/DevelopmentBoard/BrownOut.JPG
>
> Mike
>
> > Art,
> >
> > I decided that the VPOT threshold was too low so I use an integrated
> > reset button and DS1232 power monitor chip on my BX-35 Development Board
> > (http://home.austin.rr.com/perks/basicx/DevelopmentBoard.htm).
> > <http://home.austin.rr.com/perks/basicx/DevelopmentBoard.htm%29.> The
> > schematic for that part of the circuit is shown here:
> > http://home.austin.rr.com/perks/basicx/DevelopmentBoard/BrownOut.JPG.
> >
> > I think the wires XTAL2, /RST and jumper JP8 are self-explanatary.
> >
> > Mike
> >
> > > > ... Do I need to have a low voltage reset chip for the BX-35
> > >
> > > No, it's built-in. From page 19 of the Atmel AT90S8535 dox:
> > >
> > > "Reset Sources:
> > > The AT90S4434/8535 has three sources of reset:
> > > . Power-On Reset. The MCU is reset when the supply voltage is below the
> > > power-on reset threshold (VPOT)..."
> > >
> > >
> > > Tom
> > >
> > >
> > >
> > > Tom Becker
> > > --... ...--
> > > GTBecker@GTBe... www.RighTime.com
> > > The RighTime Clock Company, Inc., Cape Coral, Florida USA
> > > +1239 540 5700
> > > Yahoo! Groups Links >
>