Pic16lf877a working on 5V but not on 3.3V

Started by ntricoup August 17, 2004
Hi,
Recently i tried to make pic16lf877a work on 3.3V but with no
result. The pic is working fine on 5V with 4 or 10 MHZ. But when I
use another 3.3V voltage supply it does not work neither using 4 MHZ
nor 10MHZ. Is there something I forgot when programming the PIC? Any
idea?

What a pity Kenderis will not run at 200m race. He is faaast!
Thank you all,
Nikolaos Trikoupis



--- In , "ntricoup" <ntricoup@y...> wrote:
> Hi,
> Recently i tried to make pic16lf877a work on 3.3V but with no
> result. The pic is working fine on 5V with 4 or 10 MHZ. But when I
> use another 3.3V voltage supply it does not work neither using 4 MHZ
> nor 10MHZ. Is there something I forgot when programming the PIC? Any
> idea?

Make sure you aren't using BOR as the device will always be in reset.




And your OSC must be set for other than HS - section 15.1 of the
datasheet.

--- In , "Scott Lee" <midl_man@y...> wrote:
> --- In , "ntricoup" <ntricoup@y...> wrote:
> > Hi,
> > Recently i tried to make pic16lf877a work on 3.3V but with no
> > result. The pic is working fine on 5V with 4 or 10 MHZ. But when
I
> > use another 3.3V voltage supply it does not work neither using 4
MHZ
> > nor 10MHZ. Is there something I forgot when programming the PIC?
Any
> > idea?
>
> Make sure you aren't using BOR as the device will always be in
reset.




However acording to fig.17.2 pag.172 DS39528A it must run at 3.3V at 10MHz
and HS is starting above the 4MHz, chapter 14.2 on the same datasheet,
table 14.1, 14.2. So, run at 10MHz in XT mode, ehh ?

A good reader of the Microchip datasheet will say sometimes "Microchip
sucks". Not me, it's definitely very difficult to correct some mistakes or
inadvertences by a few guys not well payed...:)) The real problem are the
hardware informations offered by the producer in it's datasheet. Small,
incomplete and sometimes contradictory. You have to read mounrtains of
papers to be sure. And then to test.

Vasile
http://surducan.netfirms.com
On Tue, 17 Aug 2004, rtstofer wrote:

>
> And your OSC must be set for other than HS - section 15.1 of the
> datasheet.
>
> --- In , "Scott Lee" <midl_man@y...> wrote:
> > --- In , "ntricoup" <ntricoup@y...> wrote:
> > > Hi,
> > > Recently i tried to make pic16lf877a work on 3.3V but with no
> > > result. The pic is working fine on 5V with 4 or 10 MHZ. But when
> I
> > > use another 3.3V voltage supply it does not work neither using 4
> MHZ
> > > nor 10MHZ. Is there something I forgot when programming the PIC?
> Any
> > > idea?
> >
> > Make sure you aren't using BOR as the device will always be in
> reset. >
>
> to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
> Yahoo! Groups Links





What matters is getting the chip to work. Did changing OSC to
something other than HS solve the problem?

FWIW, I checked at the Digikey site and all 16LF877 are limited to 4
MHz and SOME, but not all, are identified with a -04 suffix. In
spite of the graph, they shouldn't work at 10 MHz regardless of the
voltage. Or so it seems... At least that is consistent with the
table that indicates OSC must be XT for low voltage operation. --- In , Vasile Surducan <vasile@s...> wrote:
>
> However acording to fig.17.2 pag.172 DS39528A it must run at 3.3V
at 10MHz
> and HS is starting above the 4MHz, chapter 14.2 on the same
datasheet,
> table 14.1, 14.2. So, run at 10MHz in XT mode, ehh ?
>
> A good reader of the Microchip datasheet will say
sometimes "Microchip
> sucks". Not me, it's definitely very difficult to correct some
mistakes or
> inadvertences by a few guys not well payed...:)) The real problem
are the
> hardware informations offered by the producer in it's datasheet.
Small,
> incomplete and sometimes contradictory. You have to read
mounrtains of
> papers to be sure. And then to test.
>
> Vasile
> http://surducan.netfirms.com >
> On Tue, 17 Aug 2004, rtstofer wrote:
>
> >
> > And your OSC must be set for other than HS - section 15.1 of the
> > datasheet.
> >
> > --- In , "Scott Lee" <midl_man@y...>
wrote:
> > > --- In , "ntricoup" <ntricoup@y...>
wrote:
> > > > Hi,
> > > > Recently i tried to make pic16lf877a work on 3.3V but with no
> > > > result. The pic is working fine on 5V with 4 or 10 MHZ. But
when
> > I
> > > > use another 3.3V voltage supply it does not work neither
using 4
> > MHZ
> > > > nor 10MHZ. Is there something I forgot when programming the
PIC?
> > Any
> > > > idea?
> > >
> > > Make sure you aren't using BOR as the device will always be in
> > reset.
> >
> >
> >
> >
> > to unsubscribe, go to http://www.yahoogroups.com and follow the
instructions
> > Yahoo! Groups Links
> >
> >
> >
> >
> >





I finaly turned off BOR and used a 4 MHZ with XT option. The pic was
working making many resets with no reason. Using 10 MHZ the resets
were much more. Thanx for the help. I will try to figure out what's
wrong with the resets. I don't dare to use a 2V supply ..... ;-)
In , "rtstofer" <rstofer@p...> wrote:
>
> What matters is getting the chip to work. Did changing OSC to
> something other than HS solve the problem?
>
> FWIW, I checked at the Digikey site and all 16LF877 are limited to
4
> MHz and SOME, but not all, are identified with a -04 suffix. In
> spite of the graph, they shouldn't work at 10 MHz regardless of
the
> voltage. Or so it seems... At least that is consistent with the
> table that indicates OSC must be XT for low voltage operation. > --- In , Vasile Surducan <vasile@s...>
wrote:
> >
> > However acording to fig.17.2 pag.172 DS39528A it must run at
3.3V
> at 10MHz
> > and HS is starting above the 4MHz, chapter 14.2 on the same
> datasheet,
> > table 14.1, 14.2. So, run at 10MHz in XT mode, ehh ?
> >
> > A good reader of the Microchip datasheet will say
> sometimes "Microchip
> > sucks". Not me, it's definitely very difficult to correct some
> mistakes or
> > inadvertences by a few guys not well payed...:)) The real
problem
> are the
> > hardware informations offered by the producer in it's datasheet.
> Small,
> > incomplete and sometimes contradictory. You have to read
> mounrtains of
> > papers to be sure. And then to test.
> >
> > Vasile
> > http://surducan.netfirms.com
> >
> >
> >
> > On Tue, 17 Aug 2004, rtstofer wrote:
> >
> > >
> > > And your OSC must be set for other than HS - section 15.1 of
the
> > > datasheet.
> > >
> > > --- In , "Scott Lee" <midl_man@y...>
> wrote:
> > > > --- In , "ntricoup" <ntricoup@y...>
> wrote:
> > > > > Hi,
> > > > > Recently i tried to make pic16lf877a work on 3.3V but with
no
> > > > > result. The pic is working fine on 5V with 4 or 10 MHZ.
But
> when
> > > I
> > > > > use another 3.3V voltage supply it does not work neither
> using 4
> > > MHZ
> > > > > nor 10MHZ. Is there something I forgot when programming
the
> PIC?
> > > Any
> > > > > idea?
> > > >
> > > > Make sure you aren't using BOR as the device will always be
in
> > > reset.
> > >
> > >
> > >
> > >
> > > to unsubscribe, go to http://www.yahoogroups.com and follow
the
> instructions
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >






You are pulling MCLR' high, right? If left floating the system may
reset just for entertainment.

--- In , "ntricoup" <ntricoup@y...> wrote:
> I finaly turned off BOR and used a 4 MHZ with XT option. The pic
was
> working making many resets with no reason. Using 10 MHZ the resets
> were much more. Thanx for the help. I will try to figure out
what's
> wrong with the resets. I don't dare to use a 2V supply ..... ;-) >
> In , "rtstofer" <rstofer@p...> wrote:
> >
> > What matters is getting the chip to work. Did changing OSC to
> > something other than HS solve the problem?
> >
> > FWIW, I checked at the Digikey site and all 16LF877 are limited
to
> 4
> > MHz and SOME, but not all, are identified with a -04 suffix. In
> > spite of the graph, they shouldn't work at 10 MHz regardless of
> the
> > voltage. Or so it seems... At least that is consistent with
the
> > table that indicates OSC must be XT for low voltage operation.
> >
> >
> > --- In , Vasile Surducan <vasile@s...>
> wrote:
> > >
> > > However acording to fig.17.2 pag.172 DS39528A it must run at
> 3.3V
> > at 10MHz
> > > and HS is starting above the 4MHz, chapter 14.2 on the same
> > datasheet,
> > > table 14.1, 14.2. So, run at 10MHz in XT mode, ehh ?
> > >
> > > A good reader of the Microchip datasheet will say
> > sometimes "Microchip
> > > sucks". Not me, it's definitely very difficult to correct some
> > mistakes or
> > > inadvertences by a few guys not well payed...:)) The real
> problem
> > are the
> > > hardware informations offered by the producer in it's
datasheet.
> > Small,
> > > incomplete and sometimes contradictory. You have to read
> > mounrtains of
> > > papers to be sure. And then to test.
> > >
> > > Vasile
> > > http://surducan.netfirms.com
> > >
> > >
> > >
> > > On Tue, 17 Aug 2004, rtstofer wrote:
> > >
> > > >
> > > > And your OSC must be set for other than HS - section 15.1 of
> the
> > > > datasheet.
> > > >
> > > > --- In , "Scott Lee" <midl_man@y...>
> > wrote:
> > > > > --- In , "ntricoup" <ntricoup@y...>
> > wrote:
> > > > > > Hi,
> > > > > > Recently i tried to make pic16lf877a work on 3.3V but
with
> no
> > > > > > result. The pic is working fine on 5V with 4 or 10 MHZ.
> But
> > when
> > > > I
> > > > > > use another 3.3V voltage supply it does not work neither
> > using 4
> > > > MHZ
> > > > > > nor 10MHZ. Is there something I forgot when programming
> the
> > PIC?
> > > > Any
> > > > > > idea?
> > > > >
> > > > > Make sure you aren't using BOR as the device will always
be
> in
> > > > reset.
> > > >
> > > >
> > > >
> > > >
> > > > to unsubscribe, go to http://www.yahoogroups.com and follow
> the
> > instructions
> > > > Yahoo! Groups Links
> > > >
> > > >
> > > >
> > > >
> > > >





I found an interesting behavior of some PIC's using low Q oscillator in
XT or HS mode. The problems were biggest with
ceramic resonators and only sometime dissapears with crystals. However the
amplitude on oscout was too small, near the trigger schmidt input value.
When the amplitude falling below the trigger, the PIC resets and then
"die".
If the amplitude rise above the trigger value, PIC runs ok. These
amplitude modifications may determine such crazy behavior.
One cure is to use an external oscillator and see what's happent.
Of course the other "things" like MCLR pulled somewhere, PWRTE on, BODEN
off in 3.3V mode, LVP disabled or if enabled then 10K to gnd on LVP pin,
no more than 60C ambient temperature and maybe much more... Vasile On Wed, 18 Aug 2004, rtstofer wrote:

>
> You are pulling MCLR' high, right? If left floating the system may
> reset just for entertainment.
>
> --- In , "ntricoup" <ntricoup@y...> wrote:
> > I finaly turned off BOR and used a 4 MHZ with XT option. The pic
> was
> > working making many resets with no reason. Using 10 MHZ the resets
> > were much more. Thanx for the help. I will try to figure out
> what's
> > wrong with the resets. I don't dare to use a 2V supply ..... ;-)
> >
> >
> >
> > In , "rtstofer" <rstofer@p...> wrote:
> > >
> > > What matters is getting the chip to work. Did changing OSC to
> > > something other than HS solve the problem?
> > >
> > > FWIW, I checked at the Digikey site and all 16LF877 are limited
> to
> > 4
> > > MHz and SOME, but not all, are identified with a -04 suffix. In
> > > spite of the graph, they shouldn't work at 10 MHz regardless of
> > the
> > > voltage. Or so it seems... At least that is consistent with
> the
> > > table that indicates OSC must be XT for low voltage operation.
> > >
> > >
> > > --- In , Vasile Surducan <vasile@s...>
> > wrote:
> > > >
> > > > However acording to fig.17.2 pag.172 DS39528A it must run at
> > 3.3V
> > > at 10MHz
> > > > and HS is starting above the 4MHz, chapter 14.2 on the same
> > > datasheet,
> > > > table 14.1, 14.2. So, run at 10MHz in XT mode, ehh ?
> > > >
> > > > A good reader of the Microchip datasheet will say
> > > sometimes "Microchip
> > > > sucks". Not me, it's definitely very difficult to correct some
> > > mistakes or
> > > > inadvertences by a few guys not well payed...:)) The real
> > problem
> > > are the
> > > > hardware informations offered by the producer in it's
> datasheet.
> > > Small,
> > > > incomplete and sometimes contradictory. You have to read
> > > mounrtains of
> > > > papers to be sure. And then to test.
> > > >
> > > > Vasile
> > > > http://surducan.netfirms.com
> > > >
> > > >
> > > >
> > > > On Tue, 17 Aug 2004, rtstofer wrote:
> > > >
> > > > >
> > > > > And your OSC must be set for other than HS - section 15.1 of
> > the
> > > > > datasheet.
> > > > >
> > > > > --- In , "Scott Lee" <midl_man@y...>
> > > wrote:
> > > > > > --- In , "ntricoup" <ntricoup@y...>
> > > wrote:
> > > > > > > Hi,
> > > > > > > Recently i tried to make pic16lf877a work on 3.3V but
> with
> > no
> > > > > > > result. The pic is working fine on 5V with 4 or 10 MHZ.
> > But
> > > when
> > > > > I
> > > > > > > use another 3.3V voltage supply it does not work neither
> > > using 4
> > > > > MHZ
> > > > > > > nor 10MHZ. Is there something I forgot when programming
> > the
> > > PIC?
> > > > > Any
> > > > > > > idea?
> > > > > >
> > > > > > Make sure you aren't using BOR as the device will always
> be
> > in
> > > > > reset.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > to unsubscribe, go to http://www.yahoogroups.com and follow
> > the
> > > instructions
> > > > > Yahoo! Groups Links
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
>
> to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
> Yahoo! Groups Links