This is the Revision A verion of the Harness RoboBrick. The status of this project is that it has been replaced by the Revision C version.

Harness Robobrick (Revision B)

Table of Contents

This document is also available as a PDF document.

• 1. Introduction
• 2. Programming
• 3. Hardware
  • 3.1 Circuit Schematic
  • 3.2 Printed Circuit Board
• 4. Software
• 5. Issues

1. Introduction

The Harness RoboBrick is used to test a RoboBrick network. It is built using a PIC16F84 microcontroller from MicroChip. The PIC16F84 is used so that the software can easily be changed for testing purposes. Either a dumb terminal or a terminal emulator is connected to the Harness RoboBrick via a Tether RoboBrick. Communication occurs at 2400 baud.

A picture of Harness-B is shown below (without the crystal):

2. Programming

The Harness commands are summarized as follows:

Ns

Send a single byte containing N (where N is an octal number) to the RoboBrick. Do not wait for any reply bytes.

Nw

Send a single byte containing N (where N is an octal number) to the RoboBrick. The program waits for up to 5 response bytes. If no byte is present, the byte 376 is returned. All returned bytes are printed as 3-digit octal numbers.

i

Interrogate the RoboBrick to find out its identification information.

3. Hardware

The hardware consists of a circuit schematic and a printed circuit board.

3.1 Circuit Schematic

The schematic for the Harness RoboBrick is shown below:

The parts list kept in a separate file -- Harness.ptl.

3.2 Printed Circuit Board

The printed circuit board files are listed below:

harness_back.png

The solder side layer.

harness_front.png

The component side layer.

harness_artwork.png

The artwork layer.

harness.gbl

The RS-274X "Gerber" back (solder side) layer.

harness.gtl

The RS-274X "Gerber" top (component side) layer.

harness.gal

The RS-274X "Gerber" artwork layer.

harness.drl

The "Excellon" NC drill file.

harness.tol

The "Excellon" NC drill rack file.

4. Software

The Harness software is available as one of:

harness.ucl

The µCL source file.

harness.asm

The resulting human readable PIC assembly file.

harness.lst

The resulting human readable PIC listing file.

harness.hex

The resulting Intel^® Hex file that can be fed into a PIC12C5xx programmer.

5. Issues

The following fabrication issues came up:

• Make the holes of N1 and N2 (size 3) smaller (size 2).
• Put a 1 next pin one of the crystal.
• Think about making the holes of S1 (size 4) larger (size 5).
• Increase the spacing between the capacitors.
• Add a low pass filter capacitor for U1.
• This board needs to be layed out again! It is seriously bungled!
• Add a couple of heart beat LED's.
• Find a better reset button; or just leave a 2-pin male header.
• Add a power on LED.
• Add a pin 1 next to the DB9 connector.
• It is hard to insert and remove the PIC16F628; either switch over to in-circuit programming, or move the chip to one edge.
• The crystal can is grounded; be careful not to push the crystal all the way in, or it might ground either the power or signal wire. Use crystals with longer leads.