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  Robotic Madness
  Main CPU's

My different processing units [brains]

Here is a small collection of processors that I am currently using in my robots.

Parallax BS2P40 Used in my RSV2 Generic robotic base .specs here:

Bluebells C-O Processor.

Bluebell designs C-O processor
, to off load the work from the basic stamp. Used in my Generic robotic base.
Specs here:

My BS2P which is used in my J2 robot.
Specs here:

BASIC Stamp 2SX Interpreter Chip
used in my Sensor bot and another bot in the building.
Specs here:

Atmel Attiny 26 Micro processor.
Specs Here:

Parallax BS2P24 i use two of these in my projects.
Specs here:

Just a small note on this chips power consumption and use

Now -- BS2 I/O Pins -- the BS2 'plain' is based on the PIC 16C57 microcontroller (with the Parallax proprietary run-time engine burned into it's PROM). The PIC processor was designed to be an interface processor (by MicroChip) so it's I/O pins are quite robust -- source or sink about 20 mA each. However -- the chip itself has a maximum current IT can source or sink. Meaning yes, you CAN run 20 mA through only TWO I/O pins max, before the chip overheats.

Note that 20 mA is a LOT of current for a small processor. Most applications have the BS2 put out a mA or two to control an external transistor (or LM28003 Darlington Array Chip, designed to handle lots of current) and let the transistor or Darlington handle the power.

A quick note on "power". "Power" in the IC world translates to "heat" pretty quickly (it IS measured in Watts). The Power equation is: Power == Current * Voltage. So, your linear regulator (for instance) if you drive it at 12 volts, and it's output is at 5 volts, that's a voltage drop of 7 volts. If you pull 3 mA through it, that's .003 Amps * 7 Volts == 0.021 watts. Now, your linear regulator (if it's the TO220 package) can dissapate like 5 watts (as heat -- it gets warm -- and surrounding air cools it). So you're ok.

If you pull 1 Amp through it, that's 1 Amp * 7 Volts == 7 Watts. Now, if you do that, the linear regulator will heat up so much it will go into "Thermal Shutdown". Solutions? There are several.

1) Don't pull that much current. Gee thanks, not very helpful, but sometimes you don't NEED that much current, so that's ok.

2) Put a heat-sink (using conductive grease) on the regulator. If you look up the data-sheet for the linear regulator, there's guidance there. This increases the heat-transfer area from the regulator to the air, so heat can flow faster.

Now, I told you all that to tell you this -- there's no way to put a heat-sink on a BS2 (or a 16C57, for that matter). So if you DO try to put too much current through it (60 mA through the I/O pins in this case) then it can over-heat destructively. Not to mention the driver circuitry behind individual pins will burn out if you try to run too much current through them.

And the solution to that is various I/O devices like transistors or darlington arrays or even 74HCT595 chips to off-load the current from the BS2 to some external device that CAN handle currents and heat dissapation like that.

Bottom line -- it's all good, it can all be worked around, you just have to be aware of the limits and work with them.
Above text from Allanlain5 [ Parallax forum]
Permission obtained

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