Jarod's JAL based robot bug
Date: Friday, May 06 @ 06:50:44 EDT
Topic: Tasarımcılarımız

Here are some pictures of my first real attempt at building a bug, based on schematics and tips found on endtas.com/robot. The code for the PIC microchip is completely written by me in the language JAL.


Jarod's Probug:

Here are some pictures of my first real attempt at building a bug, based on schematics and tips found on endtas.com/robot. The code for the PIC microchip is completely written by me in the language JAL. (Info about JAL can be found here.) At the moment I only have a PCB layout of the board, done on ExpressPCB. I didn't bother making a schematic at first, which really is a shame. I'll make a schematic, and a new PCB layout, because there is an error in the first PCB I made. It's nothing a little work with a knife won't fix, but I'll make a new version.

I would like to thank Özkal for all his help and input while I was struggling with this thing. And also for his great work on the site: endtas.com/robot.


This is the layout made from ExpressPCB. It's printed on a transparent sheet, using an HP DeskJet 656c.

The board is roughly cut to size but further sizing and shaping will be done using a beltsander and other handy tools.

Some retouching with a black marker-pen on the layout was needed to fill small gaps, but the inkjet printer works really great. (As long as you have transparent sheets made for inkjet printers.)

This is the board after it's exposed to UV light, developed and etched. The etching process I use take time because I don't have any equipment ment for this purpose. I use chemicals poured into small plastic containers and that's not really a good way to do it, but for small boards and small quantities it works.

After the copper is etched off, I used alcohol to rub off any remaining foto-resist, to make soldering easier.

To drill holes I used a normal drill and a 1mm bit.
That took time!

This is the underside of my bug, after all soldering and use of th hot-glue gun was done. I was actually very satisfied with the result on soldering. I have no real experience, just read articles and stuff online. Nothing was burnt, and the circuit actually worked on the first attempt.

The only "problem" was, I had to switch polarities on one motor. Both motors turned the same way, making the bug turn in circles. Quick fix.

One other thing also. The right feeler reverses the right motor. (Small reprogramming scheduled for this afternoon.)

Top-view of my bug. The battery holder is placed in a problematic place, but it's only glued in place so I'll find a new place for it. Maybe even make a "rack" for it, placing the holder above the circuitry.

The wheels are glued to the shaft's on the motors, which resulted in slipping and sliding. Not very good hold there. (The motors are also very weak, so it's barely able to roll the bug. Scavenging for better motors all the time. Parts are very expensive and delivery time is long here in Norway.)

Side view of the bug. (Taken from an angle above.) The socket for the PIC-micro is connected through to the board, using wire. The only reason for this is: The 18pin DIP I used in ExpressPCB, was WAY to big for the actual socket. (Özkal, I'll also go back to using Protel99 SE now. Allready installed it.)

The motors have 0.1uF ceramic disc caps connected between power leads.

The antenna's are made of 0.7mm wire. Will have to make new feelers because these are weak and doesn't work very well at all. Have some micro-switches that I'll see if I can use.

Another top-view of my bug. The standard AAcell in front, is there to give a sence of size.

The motors are driven by individual h-bridges. If you look close at picture, you can see the 8 transistors and 8 resistors making up the two h-bridges.

Also, about half-way down the PIC-micro on the right side, you see the resistor and cap that makes up the RC Oscillator.

This side-view of the bug, really shows the fact that the PIC-micro is elevated almost an inch above the board.

The wheels I used are taken of a RC toy car. A Mercedes in fact. The rear of the bug is supported by some steel-wire, to make sure the board doesn't catch on things on the floor.

This has been a very fun and educational project to build. I am allready working on new ideas. Some based on things seen at endtas.com, and some that I thought of myself.

Program in JAL:

include 16f84_4
include jlib

var bit H_M_A is pin_a0
var bit H_M_B is pin_a1
var bit V_M_A is pin_a2
var bit V_M_B is pin_a3
var bit H_FEELER is pin_b0
var bit V_FEELER is pin_b1
pin_b0_direction = input
pin_b1_direction = input
pin_a0_direction = output
pin_a1_direction = output
pin_a2_direction = output
pin_a3_direction = output
const bit RUN = low
const bit NRUN = high

procedure revers_h is
end procedure

procedure revers_v is
end procedure

forever loop
if H_FEELER == low then
end if
if V_FEELER == low then
end if
end loop

This article comes from Robotik & Elektronik

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