Introduction: Battery Power for the QuickStart Board

The Parallax QuickStart board normally uses the USB cable for power.
While this is handy for developing your programs, it's a bit awkward to haul a
full-blown computer around just to provide Propeller power!

My first thought was that portable power could probably be provided by a USB
wall-wart charger.

But two problems -
.    1) what do you do when there is no wall handy?
.    2) the Propeller chip's reset circuitry expects to see a computer on the other
.         end of that USB cable.

Bummer.
  ( I later found out that a jumper from pin 37 (RES or RESET) to pin 39 (Ground)
   would allow the board to run from a dumb USB charger. )


But there is an easy way to run the QS board from a battery pack.

The 40 pin expansion header has two pins just for that - pins 39 and 40 -
the two on the far right end. The top row (closest to the edge) is pin 40, which
is wired up as V-IN, the voltage supplied to the on-board voltage regulator.
We'll wire that pin to the PLUS side of the battery pack.

Pin 39 is ground. That one will be connected to the NEGATIVE side of the battery pack.

Step 1:

Connecting the battery pack backwards would be a bad thing - a VERY bad thing.
So to help prevent that from happening I recommend a 90 degree pin header to make this connection.

This is a soldering job, and a delicate one.  Bumps the soldering skill level up a lot.

Start by snipping off a piece 2 pins long.

Step 2:

Next slide the plastic part of the header strip down as far as it will go.
Grip the pins gently with pliars and press down on  the table surface until
the plastic strip moves down.

Step 3:

Soldering requires that the parts be held together steadily without any movement
while the solder is wet.  Any wiggling at that time will cause what is know as a
"cold solder joint".  That would cause higher resistance and be mechanically
weak.

So we use an alligator clip to hold the pin header while soldering.
And an alligator clip mounted on a pin vise provides a third hand that is so often
needed when doing this kind of work!

Step 4:

Carefully tin both the pins and wires.

Slip a short piece of heat-shrink tube over the wires and slide it down
away from the the ends so it won't shrink while soldering. 

Now - take a deep breath and DOUBLE CHECK the wires.
Make sure you have Positive and Negative going to the correct pins!

When soldering little things like this the parts must be motionless.
You can't make a good solder joint when the wire is moving.
You'll get a cold joint every times.

Step 5:

Now solder the wires to the pins

Getting the pins too hot will cause the plastic strip to melt, but it is
being held securely in the alligator jaws, we won't worry too much about it and just get 'er done.

With the pins clamped in place, and the wires blocked solidly in place it's quick and easy to stick
wires to pins.  

There are two wires in this picture, a red and a black.  The connection on the red wire looks nice,
shiny, clean.  All the visual indications of a good solder joint.

The one on the left, the black wire, looks like a cold solder joint.
When cool it was touched up again.

Step 6:

The next step takes time to complete, but it really helps make a sturdy reliable connector.

That's a glob of Goop - Shoe Goop is really thick, Plumber's Goop is really thin, the rest are somewhere in between.
Almost any kind of liquid cement will do.
This is Plumber's Goop, just a little dab will do ya.

Just wrap a small glob around the pins/wires and let it dry for a while before sliding the heat-shrink up in place
and shrinking it snug.

Use this technique to make cables for your bread board projects. 

Useful way to make patch cables.


Step 7:

The angled connector reduces the possibility of connecting the battery pack backwards
because the wires will always come in from the same side...

Comments

author
Gelfling6 made it!(author)2016-08-08

Awhile back, I scrapped the remains of a PS4 wireless Controller, and salvaged the 3.7V Lithium-Ion battery pack from it.. I inserted two short IDC header pins (roughly 3/8" (a little more than 1.5cm) into the pack's plug, and I soldered a 2X4 IDC socket header into the VDD/VSS pins to the right of the 40-pin header on the Quickstart. The battery pack NEVER gets charged any other method, other than plugging it into the header, and charging the pack through the onboard-3.3V regulator, while the chips are at idle (a simple print "Hello" program written to RAM, which stays dormant after it runs from the USB terminal), and the + pin plugged into the VDD pins and - pin plugged into the VSS pin of the 2X4 header. Strictly a short-term battery which will allow running the quickstart for a little while after the USB plug is unplugged. I've also run the device from a pair of Lithium-Ion batteries (2x in parallel, scavenged from a Laptop battery pack, and separated from the rest of the pack & electronics) the same way.. As long as the battery is charged through the regulator, there is little chance of the pack rising in voltage above 3.4V.. But.... this is still not a recommended method.. (already got chewed out in the Parallax forums, warning that the pack if charged normally (5V directly to the pack), it can retain up to 4.4V (.7V more), which could be detrimental to the propeller. Well understood!) I only use the packs for short-term use. Mainly for the 'Whack-A-Mole' game while waiting for other things to finish.

author
ggysbers made it!(author)2015-04-16

Almost yet not quite. In order to use the QuickStart Rev A w/ a USB charger (eg. cell phone or ipod), you need to use a 10k-ohm resistor (brown, black, orage [gold]) and bridge pin 30 (/USB_PWR_EN or "/UPE") to pin 39 (Ground or "Vss"). This is known as a pull down resistor because we are pulling /UPE to ground.

If one is having USB communication issues (eg. random characters, etc). Using a second 10k-ohm resistor and bridge pin 38 (Regulated 3.3V or "Vdd") to pin 33 (P8X32A's chip transmit pin 30 at Start Up or "I/O P30"). This is known as a pull up resistor because we are pulling the Propeller chip's pin 30 to 3.3VDC Regulated (Vdd).

Source: Parallax website, "40000-P8X32A-QuickStart-Guide-v1.3.pdf" 03/23/15

In answer to a question above, any battery pack from 6V to 9V is fine. 9V would probably be the easiest.

author
Catsruler1 made it!(author)2014-04-24

I use a 4 AA battery pack and it works great. Im sure it can be from 5 to 6 volts and still work properly. It might be a good idea to use a diode if you plan to plug it into your computer while using a battery pack at the same time.

author
celticht32 made it!(author)2013-09-26

Good idea .. just needs one last thing.. what size battery pack... what voltages etc.... might want to add that to the last part is what battery pack to use and such...

author
touren made it!(author)2013-07-31

very good ieadl & great hand make

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