• It is crucial to keep noise from the servos out of the electronics. That is why many other robot designs use multiple battery sets. One is for the electronics and another for the servos. This approach adds complexity and cost to run the robot. Our robots use one battery pack for simplicity.
  
• AA cells are first isolated with a Schottky diode and then separately regulated to give clean power to both the servos and the electronics.
  
• The regulators are both 1 Amp Low Drop-Out (LDO) type to minimize the battery power wasted by allowing the robot to perform far into the battery discharge curve. This means you can use either alkaline or rechargeable batteries in the robot. It also means you won't fry the servos if you hook the processor board up to a DC adapter for program development.
  
• A heatsink on the servo regulator gives enough dissipation capability for normal use with batteries and the included servos, but, if you need more power capability, a connector was provided to allow an external regulator with more heatsinking and higher current capability.

<= LEDs

• 1 Green LED lights to show power is on.
  
  
• 3 red Mode LEDs are provided to work with the 3 Mode switches.
  
  
• 2 red LEDs indicate a bumper hit - one is for each side.
  
  
• 2 red LEDs are connected to servo channels 6 and 7. They are mounted in the front of the PCB and are normally used to indicate that the IRPD has seen something. This is fun to watch and when developing programs it is helpful to know what the Co-Processor "thinks" it "sees".
  
  Or - independently control them using channels 6 and 7 as regular outputs unrelated to the IRPD.
  
  Or - remove the connecting jumpers and wire something else entirely to the LEDs. This especially makes sense if channels 6 and 7 are being used for servo outputs.

• There is a power switch of course.
  
  
• 3 user switches (Mode0-2) are provided to allow communication with Libby. They may be read by the BS2p program whether or not the associated LEDs are on or off. The corresponding LEDs always light while the switch is pressed.
  
  
• The Stamp reset switch allows you to restart your program at any time without having to shut off power.

• The Stamp's PC serial interface is a 9 pin female D conector.
  
  
• 24 of the unused 2p40 has I/O pins are brought out to three 20-pin headers. Each has 8 I/O pins along with unregulated power supply (2 pins), +5 Volts regulated ( 2 pins from the logic supply) and 8 grounds.
  
  20 pin IDC type cable connectors allow easy connection to external modules that need multiple I/O and power.
  
  You can also use each I/O pin separately by using 2 pin housings.
  
  
• One more unused 2p40 I/O goes to the standard 3 pin headers with I/O, Servo Power and Ground in a line.
  
  
• 3 pins are set up with a jumper to the on-board speaker. Remove the jumper to connect to that I/O and a ground for an external sound module or whatever else you have in mind.
  
  
• 3 pins are available to connect to the 3 Mode I/O pins - in case the other 25 aren't you enough and don't want to use the built-in switch/LED sets.
  
  
• 3 pins allow probing or connection to the 2p40 I/O pins used for the Co-Processor interface. - Which leads us to ...

• 8 Servo/General Purpose outputs use the standard 3 pin headers with Output, Servo Power and Ground in a line.
  
  
• 10 pins bring in 4 of the 10 bit A/D channels. To allow the A/D inputs to go to an external analog module there is a +5 logic power pin. The remaining 5 pins are grounds. The layout allows either a single 10 pin IDC type cable connector (2X5) or separate 2 pin housings to access each A/D input pin independently.
  
  
• The 2 red LEDs used with output chanels 6 and 7 each are wired through jumpers to allow reconnecting them to other places.
  
  
• The Bumper input pins (2 for each side) are really just pulled up inputs with display LEDs. If the bumper is not installed, you can use them as general inputs or as connections to your own bumper wiring. They can be read by the 2p40 from the Robot Status Byte.
  
  
• Do want to make your own Co-Processor? The Co-Processor is socketed. If you really want to get into the details of programming, or, if you are using the PCB for something other than a robot, you can unplug the Co-Processor and put a 28 pin Microchip PIC^® 16F87X in its place.
  
  There is a 5 pin header to allow you to attach a low cost MPLAB^® ICD In-Circuit Debugger Development Tool by making a simple cable. You can then download your program using In-Circuit Serial Programming ^®. That way you can use C, High Speed compiled BASIC, or assembly language to control your project. You will still have the BASIC Stamp^® 2p40 to do other computing tasks at the same time! (Extra 16F87X PIC, cable, ICD, compilers or assemblers are not included.)
  
  The Co-Processor external interrupt input pin is pulled up to +5V. It is also connected to a 2 pin header with the input and a ground, so you can connect to it for your co-processor designs.

• A 6 pin header (J6) has 2 pins connected to Vin (Raw Battery input), one pin to ground and 3 to the Servo +5V supply. These connections can be used to get the power off board for an external module or can be the connections to an external higher power regulator.
  
  
• A 3 pin header (J16) has all 3 pins connected to VinAS (Raw Battery input after the Schottky isolation diode). This is the voltage that drives the logic regulator and after being divided by 2, is measured by A/D channel 0 .
  
  
• The two bumper mounting studs are both connected to ground.
  
  
• The four PCB mounting holes are all connected to ground.