This is the Revision A verion of the RoboBRiX Irline2 module. The status of this project is work in progress.

Irline2 (Revision B)

Table of Contents

This document is also available in PDF format.

1. Introduction

The IRLine2 RoboBrix can connect to operate 2 Fairchild® QRB1134 Infrared photorelective sensors. These sensor can detect the difference between light and dark at a distance about 4mm (.15 inches.) Thus, they are excellent for detecting the edges of lines for line following robots. The two QRB1134's are mounted directly on the IRLine2. The board is mounted on edge with the two sensors facing down toward the floor and stradling the line to be followed. The QRB1134 sensers can be moved back and forth across the board edge to accomadate different line widths.

2. Programming

The IRLine2 RoboBrix is continuously reading the analog inputs from its four A/D pins. The controlling program can just read the results of the digital conversion, or it can have the result down converted into a single binary bit. Each pin has has a threshold high and threshold low register that is used for the down conversion. Whenever the digital conversion exceeds the high threshold register, the down coversion results in a 1. Whenever the digital conversion is lower than the low threshold register, the down conversion results in a 0. A hysterisis effect can be introduced by having some spread between the high and low threshold values.

After the down coversions to binary bits, the result is 4-bits of binary data. A complement mask can be used to selectively invert individual bits in the 4-bit data.

The IRLine2 RoboBrix supports RoboBrix Interrupt Protocol for those lines that are being used as inputs. The interrupt pending bit is set whenever the the formula:

L&(~I) | H&I | R&(~P)&I | F&P&(~I)
is non-zero, where: and Once the interrupt pending bit is set, it must be explicitly cleared by the user.

In addition to the common shared commands and the shared interrupt commands, the IRLine2 RoboBrix supports following commands:
Command Send/
Receive
Byte Value Discussion
7 6 5 4 3 2 1 0
Read Pin Send 0 0 0 0 0 0 b b Read pin bb and respond with 8-bit value vvvvvvvv
Receive v v v v v v v v
Read Binary Values Send 0 0 0 0 0 1 0 0 Return the binary values abcd (after XOR'ing with complement mask)
Receive 0 0 0 0 a b c d
Read Raw Binary Send 0 0 0 0 0 1 0 1 Return the raw binary values abcd (no XOR with complement mask)
Receive 0 0 0 0 a b c d
Reset Send 0 0 0 0 0 1 1 0 Reset everything to zero
Read Complement Mask Send 0 0 0 0 1 0 0 0 Return the complement mask cccc
Receive 0 0 0 0 c c c c
Read High Mask Send 0 0 0 0 1 0 0 1 Return the high mask hhhh
Receive 0 0 0 0 h h h h
Read Low Mask Send 0 0 0 0 1 0 1 0 Return the high mask llll
Receive 0 0 0 0 l l l l
Read Raising Mask Send 0 0 0 0 1 0 1 1 Return the raising mask rrrr
Receive 0 0 0 0 r r r r
Read Falling Mask Send 0 0 0 0 1 1 0 0 Return the falling mask ffff
Receive 0 0 0 0 f f f f
Read High Threshold Send 0 0 0 1 0 0 b b Return high threshold for pin bb of hhhhhhhh
Receive h h h h h h h h
Read Low Threshold Send 0 0 0 1 0 1 b b Return low threshold for pin bb of llllllll
Receive l l l l l l l l
Set High Threshold Send 0 0 0 1 1 0 b b Set high threshold for pin bb to hhhhhhhh
Send h h h h h h h h
Set Low Threshold Send 0 0 0 1 1 1 b b Set low threshold for pin bb to llllllll
Send l l l l l l l l
Set Complement Mask Send 0 0 1 0 c c c c Set complement mask to cccc
Set High Mask Send 0 1 0 0 h h h h Set high mask to hhhh
Set Low Mask Send 0 1 0 1 l l l l Set low mask to llll
Set Raising Mask Send 0 1 1 0 r r r r Set raising mask to rrrr
Set Falling Mask Send 0 1 1 1 f f f f Set falling mask to ffff
Read Interrupt Bits Send 1 1 1 0 1 1 1 1 Return the interrupt pending bit p and the interrupt enable bit e.
Receive 0 0 0 0 0 0 e p
Set Interrupt Commands Send 1 1 1 1 0 c c c Set Interrupt Command ccc.
Shared Commands Send 1 1 1 1 1 c c c Execute common shared command ccc

3. Hardware

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

3.1 Circuit Schematic

The schematic for the IRLine2 RoboBrix is shown below:

IRLine2 Schematic

The parts list kept in a separate file -- irline2.ptl.

3.2 Printed Circuit Board

The printed circuit board files are listed below:

irline2_back.png
The solder side layer.
irline2_front.png
The component side layer.
irline2_artwork.png
The artwork layer.
irline2.gbl
The RS-272X "Gerber" back (solder side) layer.
irline2.gtl
The RS-272X "Gerber" top (component side) layer.
irline2.gal
The RS-272X "Gerber" artwork layer.
irline2.drl
The "Excellon" NC drill file.
irline2.tol
The "Excellon" tool rack file.

3.3 Construction Instructions

The construction instructions are in a separate file to be a little more printer friendly.

4. Software

The IRLine2 software is available as one of:

irline2.ucl
The µCL source file.
irline2.asm
The resulting human readable PIC assembly file.
irline2.lst
The resulting human readable PIC listing file.
irline2.hex
The resulting Intel® Hex file that can be fed into a PIC programmer.

The IRLine2 test software is available as one of:

irline2_test.ucl
The µCL source file.
irline2_test.asm
The resulting human readable PIC assembly file.
irline2_test.lst
The resulting human readable PIC listing file.
irline2 _test.hex
The resulting Intel® Hex file that can be fed into a PIC programmer.

5. Issues

Any fabrication issues will be listed here.


Copyright (c) 2001-2002 by Wayne C. Gramlich. All rights reserved.