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Step 2Circuit of a One Cubic Inch Robot
Pic 4 shows the location of the 18x Picaxe microcontroller and the L293 motor controller which are the main circuits of the robot. At the time of construction, I could not obtain the surface mount versions of the Picaxe or the L293. Using the surface mount ICs would certainly leave more room for additional circuits and sensors.
18x Picaxe Microcontoller
Picaxe microcontrollers are still my favorite controllers to use on experimental robots. While they have less memory and are not as fast as PicMicros, Arduino, Basic Stamp, or other microcontrollers, they are fast enough for most small experimental robots. Several of them can be easily connected together when more speed or memory is needed.
They are also very forgiving. I have directly soldered them, shorted them and overloaded their outputs and I have yet to burn one out. Because they can be programmed in the BASIC programming language, they are also easier to program than most microcontrollers. If you want to build really small, the 08M and 18x Picaxe controllers are available in surface mount form (SOIC-Small Outline Integrated Circuits).
To see some of the projects you can do with Picaxe microcontrollers you can take a look at:
http://www.inklesspress.com/picaxe_projects.htm
L293 Motor Controller
The L293 motor controller is an excellent way to control two motors in any small robot. Four output pins from the microcontroller can control the power to two motors: forward, reverse, or off. The power to the motors can even be pulsed (PWM-pulse width modulation) to control their speed.
Dead Bug Style
There was not room on the perfboards to mount the L293 controller so it was installed using the dead bug technique. This simply means that the IC is turned upside down and thin wires soldered directly to the pins which have been bent or clipped short. It can then be glued onto a circuit board or fitted into any available space.
In this case, after the L293 was soldered and tested, I coated it with two coats of the ever handy Liquid Tape rubber to insure that nothing shorted out when it was crammed into the available space. Clear contact cement could also be used.
For a very good example of building circuits using the dead bug style, see here: http://www.bigmech.com/misc/smallcircuit/
Pic 5 shows a helping hands solder jig I have modified by adding small alligator clips to a perfboard to aid in soldering small wires to ICs in the dead bug style.
Pic 6 shows the schematic for the Mr. Cube robot.
You can see a video of Mr. Cube doing a short programmed sequence by clicking on the inch-robot-sm.wmv link below.
It shows the robot at about 30% of top speed which has been reduced using pulse width modulation on the motors.
18x Picaxe Microcontoller
Picaxe microcontrollers are still my favorite controllers to use on experimental robots. While they have less memory and are not as fast as PicMicros, Arduino, Basic Stamp, or other microcontrollers, they are fast enough for most small experimental robots. Several of them can be easily connected together when more speed or memory is needed.
They are also very forgiving. I have directly soldered them, shorted them and overloaded their outputs and I have yet to burn one out. Because they can be programmed in the BASIC programming language, they are also easier to program than most microcontrollers. If you want to build really small, the 08M and 18x Picaxe controllers are available in surface mount form (SOIC-Small Outline Integrated Circuits).
To see some of the projects you can do with Picaxe microcontrollers you can take a look at:
http://www.inklesspress.com/picaxe_projects.htm
L293 Motor Controller
The L293 motor controller is an excellent way to control two motors in any small robot. Four output pins from the microcontroller can control the power to two motors: forward, reverse, or off. The power to the motors can even be pulsed (PWM-pulse width modulation) to control their speed.
Dead Bug Style
There was not room on the perfboards to mount the L293 controller so it was installed using the dead bug technique. This simply means that the IC is turned upside down and thin wires soldered directly to the pins which have been bent or clipped short. It can then be glued onto a circuit board or fitted into any available space.
In this case, after the L293 was soldered and tested, I coated it with two coats of the ever handy Liquid Tape rubber to insure that nothing shorted out when it was crammed into the available space. Clear contact cement could also be used.
For a very good example of building circuits using the dead bug style, see here: http://www.bigmech.com/misc/smallcircuit/
Pic 5 shows a helping hands solder jig I have modified by adding small alligator clips to a perfboard to aid in soldering small wires to ICs in the dead bug style.
Pic 6 shows the schematic for the Mr. Cube robot.
You can see a video of Mr. Cube doing a short programmed sequence by clicking on the inch-robot-sm.wmv link below.
It shows the robot at about 30% of top speed which has been reduced using pulse width modulation on the motors.
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1
Jul 6, 2010. 5:36 AMsourcer
says:
is it able to avoid obstacles? can you leave your source code for your robot on this instructable? and also, can you draw a diagram with only one power supply version for us? thanks alot
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5
Jul 20, 2010. 6:04 AMraykholo
says:
That schematic only has one power source (alll grounds go to the same place). On top of that, the author specifically mentioned that using one power supply was a bad idea (step 3)
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Jun 27, 2010. 11:35 AMchickens.do.have.lips
says:
Really nice project! I just have a few questions, though; would you happen to know if the PICAXE 18X can use two L293 Motor Drivers, since it has 8 output pins? I've been wondering if I could use two extra motors for this kind of project. Speaking of capacitors, would I be able to use a 100uf capacitor for this project, or is there a recommended range for the capacitor used in this project? I looked at the project board for this microcontroller, and there is a capacitor, as well as a few resistors; did you use the same resistor values as the ones from the project board on your project? I've been thinking about just buying the resistors, caps, and ICs from the board instead of buying the board. Please reply, and Thanks!
Reply
Nov 17, 2008. 12:12 PMHomebuilder
says:
Hi there I'm Erik and i'm come from holland. My quastion is were is the Serin and Serout for? is there something to connect to it? Hire in holland is the 150uf very hard to get. So i bought an 220. Can i juste it to with out distrubing the working of the circuit? I'f reed about the 25:1 gearmotors. I can't find them on the link. I only find the 30:1. Bit slower but i think its juisefull. I like to know more about this robot circuit :) Greetings Erik
Reply
26
Nov 17, 2008. 6:57 PM
mikey77 (author)
says:
mikey77 (author)
says:
A 220uf capacitor will work good. A 30:1 gear motor will work good also. The Serin and Serout pins are used to program the Picaxe microcontroller. The Picaxe is programmed using the serial port of a Windows PC. Read the comments below to find out where you can get a Picaxe microcontroller and information on how to program it with your PC. Read the comments below to find out more about this circuit. This looks like a simple circuit and a simple robot, but it actually requires fairly advanced electronic and programming skills to build it.
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