It really helps a Toddler - and it just screws right on!

Start with your Toddler - but then ...

The Parallax Toddler is a popular BASIC Stamp®2 processor based hobby and educational biped walker robot. Like the BoE-Bot, it comes with excellent courses to get a starting roboteer going. Walkers are a special challenge in that the servo control has to be ramped from position to position. Just keeping up with the servos can actually take up most of the processing power of the BS2. A typical non-ramping servo controller won't be much help because the Stamp will still have to recompute the new servo positions every 20 ms. Our ramping servo controller takes the real-time effort away. This makes it easy and effective to add the tilt sensors or additional servos for whatever you have in mind.

Step up to outstanding new computing power while still keeping the Stamp you know and love! Use our new low-cost PCB Kit to make adding our Co-Processor easy. See the Buy-a-Bot page to buy the Co-Processor, Bare PCB, or the complete kit. Mounting holes line up exactly so it fits directly under the Toddler board. Underneath mounting keeps the reset switch, and proto and AppMod areas accessible. Use of the Co-Processor gains several Stamp I/O pins. On-board LEDs are programmable to show the internal status of the Toddler program. Get back 3 Stamp byte variables. Three wire (servo style) A/D connections are perfect for Sharp GP2D12 IR distance sensors. Provides + 5V power, ground, and A/D input in one cable. How about a wall following Toddler? 8 servo controller connections for easy addition of arms, head, camera pan-tilt, sensor rotation servos, whatever! Frees the proto area for the next things you want to add! The AppMod connector is still available, so, if you want to use it, you can. It's Low Cost and Available NOW! Here is the schematic (2 pp - PDF - 23 KB). The photos show 4 LEDs on the Co-Processor board. The production version of Parallax' Toddler Toes has LEDs built into them so we don't really need the bumper LEDs, but hey, why not add them anyway? Here is the most simple code listing as a text file. If you have a tilt sensor, look at the Memsic code. For smoother movement and less vibration, you can start and finish the movements at a lower speed than the main travel. That is done in the stepped speed code. Notice that even the most sophisticated stepped speed code only takes 65% of the EEPROM (code) space and 35% of the register space. Toddler still has lots of room for your expansions! Because the Toddler uses a 4 cell supply, the kit comes with the Co-Processor Brownout disabled. Look at the discussion on brownout detection for more information.

<= Co-Processor Add-Under PCB.
	Left is a top view of the Toddler with the processor board removed. The Co-Processor IRPD parts aren't used here because we are using the ones built in to the Toddler. The bumpers are "Toddler Toes" and so the Co-Processor bumpers aren't used here either. That meant the LEDs were available.

The A/D and servo controllers 0-3 are brought to connectors. Since we aren't using the bumpers here, why not use some wires (we used white ones) to connect the bumper LEDs to servo channels 4 and 5? Since servo outputs can also be set up as programmable outputs, the LEDs connected to servo outputs 4-7 are now also general purpose indicators. Here we left off the J4 servo connector but you could keep it on. LEDs on servo outputs just glow dimly when the servo is running. No harm is done. That way you can use channels 4-7 either as LED drivers or as servo outputs without changing the wiring. The outputs are all separate so you could use any combination of servo drivers and straight outputs (LED drivers here) for the channels.

<= The wiring side.
	This view shows the clean and simple wiring between boards. The two white-red-black wires on the left are from the "Toddler Toes". Servo power is taken from one of the servo connectors so the power switch will still control servo power separately. +5 is plugged into the VDD connector.

Servo style connectors can make it easy to connect the Co-Processor signal lines to the Toddler PCB. The newest program requires the wires to be plugged in differently than how they are in this picture. The yellow wires are both connected to inputs (reset and serial input). They are put to the middle of the servo style connectors so if they are ever accidentally plugged into a powered servo connector, there will be no damage. It won't work but it may not hurt anything. There could still be two outputs fighting, but that is better than an output trying to pull a supply down.

How about the Co-Processor Board with a BoE-Bot? Click Here or on the Blue Bell Logo at the top to return to Home. Copyright © 2003 Blue Bell Design, Incorporated. All rights reserved. Blue Bell Design Inc. Post Office Box 446 Gwynedd Valley, PA 19437-0446 USA 215-643-7012 email us harry@bluebelldesign.com on the web www.bluebelldesign.com BASIC Stamp®is a registered trademark of Parallax, Inc.