Searching \ for 'problem with circuit startup' 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/index.htm?key=problem+with+circuit
Search entire site for: 'problem with circuit startup'.

Truncated match.
PICList Thread
'problem with circuit startup'
1995\11\05@180039 by Walter Anderson

flavicon
face
I've put together a simple circuit board for use in prototyping PIC
projects.  The board is constructed using wire wrapping techniques.
I've hooked the proto board up to a simple breadboard circuit
consisting of LEDs and resitors connected to each of the ports on
port A & B.

MCLR tied to +5v through a 1k resistor, with a pushbutton switch to
ground to provide a reset switch.  OSC1, OSC2 to a xtal and two caps.
RA4/RTCC is tied to +5v

The problem is the circuit doesn't startup properly.  Using a freq
cntr I've checked the oscillator and it is runnning.  Turning off the
power supply to the circuit starts it as the power supply discharges.
By reapplying power the circuit will continue to function; however,
when I press the reset button the circuit fails to restart.

BTW, the WDT, is off

Any ideas about what is causing the problem?
------------------------------------------------------------
Walter Anderson, CCP          email: spam_OUTwandrsonTakeThisOuTspamonramp.net
2500 Guerrero, #221           callsign: KD4KIL
Carrollton, Texas 75006       url: <in progress>
------------------------------------------------------------

1995\11\06@053433 by Conny Andersson

flavicon
face
At 16.57 1995-11-05 +0000, Walter Andersson wrote:

>I've put together a simple circuit board for use in prototyping PIC
>projects.  The board is constructed using wire wrapping techniques.
>I've hooked the proto board up to a simple breadboard circuit
>consisting of LEDs and resitors connected to each of the ports on
>port A & B.

I hope you don't overload your PIC with all these LED:s. Normally each
LED should get 10-20mA and 10 of them should have up to 200mA, way too
much for our little friend. For the PIC16C5X series the absolute maximum
rating is 150mA out of the VSS pin and max 50mA in to VDD pin. Max output
sunk by a single I/O port is 50mA and max output current sourced by a
single I/O port is 40mA. Each port pin can take 20mA alone (sourced) and
25mA (sunk). Well, maybe it works anyway but it wont hurt to be on the
legal side ... :)

>MCLR tied to +5v through a 1k resistor, with a pushbutton switch to
>ground to provide a reset switch.  OSC1, OSC2 to a xtal and two caps.
>RA4/RTCC is tied to +5v

Try to add a low pass network and some diodes to your switch. It will help
to debounce and make a slow reset. There are a few good circuits in the
uC-databook.

You might also need a smoothing capacitor say 100nF at each digital IC and
connected between VDD and VSS.

>The problem is the circuit doesn't startup properly.  Using a freq
>cntr I've checked the oscillator and it is runnning.  Turning off the
>power supply to the circuit starts it as the power supply discharges.
>By reapplying power the circuit will continue to function; however,
>when I press the reset button the circuit fails to restart.

Look at your power rails close to the pic via an oscilloscope, It
might help you locate the problem source.

>BTW, the WDT, is off

Aha, that's nice!

-- Conny

1995\11\06@144923 by adrian

flavicon
picon face
you wrote:

> At 16.57 1995-11-05 +0000, Walter Andersson wrote:
>
> >I've put together a simple circuit board for use in prototyping PIC
> >projects.  The board is constructed using wire wrapping techniques.
> >I've hooked the proto board up to a simple breadboard circuit
> >consisting of LEDs and resitors connected to each of the ports on
> >port A & B.
>
> I hope you don't overload your PIC with all these LED:s. Normally each
> LED should get 10-20mA and 10 of them should have up to 200mA, way too
> much for our little friend. For the PIC16C5X series the absolute maximum
> rating is 150mA out of the VSS pin and max 50mA in to VDD pin. Max output
> sunk by a single I/O port is 50mA and max output current sourced by a
> single I/O port is 40mA. Each port pin can take 20mA alone (sourced) and
> 25mA (sunk). Well, maybe it works anyway but it wont hurt to be on the
> legal side ... :)

I have some LEDs connected to a PC16C84. They are 4x7segment displays
for a game for my daughter. I have connected the LEDs directory as
a 4x8 matrix, and I multiplex 1/8. I reasoned that this was not going to
get things to hot (i.e. max 4 LEDs at any one time). Also, over driving the
LEDs a bit seems to make up for the low mux rate.

Seems to work fine.

With 13 IO lines I have 4 x 7 seg digits (plus decimal point) and 6 buttons
and a buzzer (piezo). I did have to put diodes in with the buttons !

--
_
(_) _| _ . _  _   Tel +44 973 222257
( )(_|(  |(_|| )  Fax UK 0500 222258                    E&OE

More... (looser matching)
- Last day of these posts
- In 1995 , 1996 only
- Today
- New search...