Searching \ for '[PIC]: Trick to running at 3V?' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/microchip/devices.htm?key=pic
Search entire site for: 'Trick to running at 3V?'.

Exact match. Not showing close matches.
PICList Thread
'[PIC]: Trick to running at 3V?'
2003\05\28@171102 by Alex Kilpatrick

flavicon
face
I am attempting to get a PIC to run at 3.3 V.  Basically, I have the
standard blinking LED circuit, which works fine with a 5V regulator.  If
I swap the 5V regulator for a 3.3V regulator (getting 3.24 out), I get
nada.  The LED pin seems to be at about 1.7 V.  If I remove the LED, the
pin is at .06 V.   Any ideas?  Is there anything special I need to do to run at 3V?
Thanks!
Alex

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2003\05\28@171933 by Dipperstein, Michael

face picon face
Do you have brownout enabled?

-Mike

-----Original Message-----
From: Alex Kilpatrick [spam_OUTAlexKTakeThisOuTspamHCITRAINING.COM]
Sent: Wednesday, May 28, 2003 2:11 PM
To: .....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU
Subject: [PIC]: Trick to running at 3V?


I am attempting to get a PIC to run at 3.3 V.  Basically, I have the
standard blinking LED circuit, which works fine with a 5V regulator.  If
I swap the 5V regulator for a 3.3V regulator (getting 3.24 out), I get
nada.  The LED pin seems to be at about 1.7 V.  If I remove the LED, the
pin is at .06 V.

Any ideas?  Is there anything special I need to do to run at 3V?

Thanks!

Alex

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2003\05\28@172520 by Alex Kilpatrick

flavicon
face
> -----Original Message-----
> From: Dipperstein, Michael [mdippersspamKILLspamHARRIS.COM]
> Sent: Wednesday, May 28, 2003 4:20 PM
> To: .....PICLISTKILLspamspam.....MITVMA.MIT.EDU
> Subject: Re: [PIC]: Trick to running at 3V?
>
>
> Do you have brownout enabled?
>
> -Mike
>
That was it.  2 minutes of downtime, thanks!!  :-)

I had never used brownout before; I guess it defaults to 'on.'  So, can
you not use it if you are using 3V supply?

Alex

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2003\05\28@173557 by Dipperstein, Michael

face picon face
> -----Original Message-----
> From: Alex Kilpatrick [EraseMEAlexKspam_OUTspamTakeThisOuTHCITRAINING.COM]
> Sent: Wednesday, May 28, 2003 2:25 PM
> To: PICLISTspamspam_OUTMITVMA.MIT.EDU
> Subject: Re: [PIC]: Trick to running at 3V?
>

<snip>

> I had never used brownout before; I guess it defaults to
> 'on.'  So, can
> you not use it if you are using 3V supply?

The PIC18s have a user selectable brownout threshold, with some thresholds below
3V.  None of the other PICs will run at 3V with brownout detection enabled.

-Mike

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2003\05\28@180233 by Mike Harrison

flavicon
face
On Wed, 28 May 2003 16:24:31 -0500, you wrote:

>> -----Original Message-----
>> From: Dipperstein, Michael [@spam@mdippersKILLspamspamHARRIS.COM]
>> Sent: Wednesday, May 28, 2003 4:20 PM
>> To: KILLspamPICLISTKILLspamspamMITVMA.MIT.EDU
>> Subject: Re: [PIC]: Trick to running at 3V?
>>
>>
>> Do you have brownout enabled?
>>
>> -Mike
>>
>
>That was it.  2 minutes of downtime, thanks!!  :-)
>
>I had never used brownout before; I guess it defaults to 'on.'  So, can
>you not use it if you are using 3V supply?
No, You also can't use it if you want half-sensible sleep power consumption - it drawsa ridiculous
amount of power compared to external brownout reset chips.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2003\05\29@050816 by hael Rigby-Jones

picon face
{Quote hidden}

There are many potential gotchas running the PIC at low voltages, these are
a few that I have found:

The standard '16F' parts are not specced for operation below 4volts.
The maximum frequency you can run an '16LF' PIC at 3.3volts is typicaly half
the maximum at 5volts.  The datasheet gives exact details of this.
Some resonators may not start reliably using the normal fuse setting; I
found that I needed to use the HS oscillator configuration to ensure
reliable startup with the particular 4MHz resonator we use at 3.3volts.
You cannot perform a bulk erase at 3.3 volts, so re-programming the
configuration fuses isn't possible after the first time (unless you raise
Vdd to 4.5volts).
The ICD1 will often not work correctly at 3.3 volts without modification.
The output ports, being CMOS, are noticeably weaker at 3.3 volts than 5
volts.

Regards

Mike


=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================
Any questions about Bookham's E-Mail service should be directed to postmasterEraseMEspam.....bookham.com.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\05\29@055912 by Alan B. Pearce

face picon face
>The ICD1 will often not work correctly at 3.3 volts without modification.
>The output ports, being CMOS, are noticeably weaker at 3.3 volts than 5
>volts.

IIRC Microchip have a modification to allow this. I think it involves a
16LF876 and a resistor change. See ETN21 IIRC.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\05\29@081815 by Jinx

face picon face
> There are many potential gotchas running the PIC at low voltages,
> these are a few that I have found:

Today I got given a couple of motor controller units to evaluate from
a large (in the 1000s) UK production run using the 12C671. I'm told
that a similar circuit has been made for many years (not with a 671
presumably) "without complaints". Apparently 10% of these units,
which are used for golf carts, historically "go funny". The biggest
fault is that despite having 12VDC available, the micro is allowed
a paltry 2.2V via a 2.7V zener and there are no filter caps. No
wonder they "go funny"

Many other things are out-of-spec or very close to it. For example
a 25k pot on the ADC, and half the pot's travel is wasted putting
out too-low duty cycle PWM (at an annoying 150Hz), the pot has
to be hard CCW to completely stop pulses going to the motor (no
off switch - no sleep), no reverse polarity protection, one of the 3
planned-for FETs is out to make room for a thick motor wire. etc
etc etc. And for some reason it shuts the motor down after 10
minutes. It's probably the crappiest piece of junk I've seen for a
long time and it's surprising any of them work at all. Looks like I
might have my next job ;-)))))

(just a wee post prompted by incredulity at both the shoddy work-
personship and price)

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\05\29@084626 by hael Rigby-Jones

picon face
> -----Original Message-----
> From: Alan B. Pearce [SMTP:EraseMEA.B.PearcespamRL.AC.UK]
> Sent: Thursday, May 29, 2003 10:59 AM
> To:   RemoveMEPICLISTEraseMEspamEraseMEMITVMA.MIT.EDU
> Subject:      Re: [PIC]: Trick to running at 3V?
>
> >The ICD1 will often not work correctly at 3.3 volts without modification.
> >The output ports, being CMOS, are noticeably weaker at 3.3 volts than 5
> >volts.
>
> IIRC Microchip have a modification to allow this. I think it involves a
> 16LF876 and a resistor change. See ETN21 IIRC.
>
Damn, I even had the link ready to paste into my email and totaly forgot!

http://www.microchip.com/download/tools/picmicro/icds/mplabicd/etn21d.pdf

Regards

Mike


=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================
Any questions about Bookham's E-Mail service should be directed to RemoveMEpostmasterspam_OUTspamKILLspambookham.com.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

More... (looser matching)
- Last day of these posts
- In 2003 , 2004 only
- Today
- New search...