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[DPRG] Problem with Botboard Plus and PCBug

Subject: [DPRG] Problem with Botboard Plus and PCBug
From: Earl Bollinger earlwbollinger at attbi.com
Date: Thu Feb 20 04:23:01 CST 2003

My first thought is; How are you powering the board? Are you using a 5 volt
regulator IC, or a external 5v power supply or something?
     What is the voltage of what you are using to power the board? before
you hook it up to the board, after hooking it up, and when the
        board flakes out.
     If it is over 5v you could have problems, 5.5v is usually max for most
chips, it maybe slowly overheating and flaking out.
        By the same token, if it is too low of a voltage, 4.5v or below, it
can start to flake out too.
     If you using a 7805 type of voltage regulator, is it overheating? The
regulators usually will turn themselves off if they get
           overloaded or overheated.
     If your using a external powersupply, it may be overheating and going
bad on you too. I've seen these little wall warts cause
         more problems than they are worth.
     Measuring the current draw of the board when it is powered up might be
a good idea, as something might be drawing
        too much power. Do you have anything hooked up via the breadboard
area on the board?
     If you are using a battery, is it fresh, or needs recharging? You'd
need to check the battery voltage before
        you hook it up to the board, "no load".
        Then you need to check the voltage level after hooking it up to the
        Then check the voltage level periodically up until it flakes out.

 A lot of the small external AC adaptors let a lot of AC ripple come though
on the DC output as noise. Usually this doesn't pose too many problems. But
filtering it more helps too. You might be getting noise in from the AC lines
and that could possibly cause a problem if the noise gets onto the MCU's
reset line. Thus the chip might just flake out every now and then. Any power
glitches? Such as the light
flickering or something. Someone running the vaccum cleaner, hand drill or
something while your working on the board?

A similar problem happens with solenoids, relays, motor controllers and
such, being hooked up on the board and activated. The devices generate noise
that can cause the MCU to flake out. Are you using any of these devices on
your BotBoard?

Does it flake out with the PC attached via the serial port or not attached
to the serial port?
  In this case we might be getting a noise or ground loop problem coming in
>from that side.

Last but not the least, could this be a program problem? The program runs
for 15 minutes or so then the MCU stops. This would imply a
  stack problem or a condition that isn't being considered in the software.
This may actually wind up being a problem with the
 PCBug program in relation to the PC and the serial communications port, not
with the botboard at all.

If you program the botboard with a simple LED blinker program. Does the
botboard still run when the PCBug software stops communicating with it? Or
not?  If you don't have a LED hooked up, you can monitor a I/O pin with the
voltmeter and watch it (I/O pin) go high and low every second or so,
depending on the program.

If your running the botboard from a battery, can you program it? You can
bring it to the Robot Power Lunch or RBNO, we have a couple/three
   68HC11 experts that usually show up that can take a look see. If you have
a voltmeter bring it too. If you can demo the problem with a simple LED
blinker program or something, that would be great.
  -----Original Message-----
  From: dprglist-admin at dprg.org [mailto:dprglist-admin at dprg.org]On Behalf Of
Kyle Reynolds
  Sent: Wednesday, February 19, 2003 11:33 PM
  To: dprglist at dprg.org
  Subject: [DPRG] Problem with Botboard Plus and PCBug

  I am new to the 68hc11 and I recently put together the Botboard plus and
all the tests ran fine and everything seems to be working as it is supposed
to except that after about 15 minutes, PCBug will lose communication with
the board.  If I let it "rest" for a while (power off), it will work
again...  The board doesn't get hot, but time seems to heal the problem...
Does anyone have any suggestions as to where I should begin my search for
the culprit?  I appreciate the advice.


  Kyle Reynolds
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