Content in “picaxe”

Breadboard Basics II (Add PICAXE)

jklug80 — Sun, 11 May 2008 03:21:26 +0200

Time to add PICAXE to the board.

This requires:

A breadboard
5volt power source
PICAXE 28x1 chip
Stereo Socket
USB or Seriel Transfer cable
4k7 ohm resistor
330 ohm resistor
LED
Wire

I'm not going to go into detail about how to hook things up. If you are having problems and the images aren't helping I will answer questions if I can :) Basically all this did was help me to learn how to hook up the chip and a stereo socket to a breadboard and get basic output (blinking LED). Hopefully it will help someone else too! Lots of pics to follow so you can see how it is connected. The code follows the pictures.

For help on how to hook up the stereo socket or for what pins do what on the chip click here.

Symbol LED = 0

AGAIN:
HIGH LED
pause 1000

LOW LED
pause 1000

GOTO AGAIN

END

The code assumes you are using output 0 for the LED. If you can't get the editor to connect to your chip make sure you have the com port setting correct.

Click START (lower left corner of your screen)
Right click My Computer
Click Properties
Click Hardware Tab
Click Device Manager Button
Expand the Ports (COM & LPT)
It should have an item called AXE027 PICAXE USB (COMX) X is your COM Port Number
In the editor go to View->Options
Click Seriel Port tab
Select the Com Port you found in step 7 and click OK
Try to transfer the code again.
If it still doesn't work make sure your batteries are charged and connected to the breadboard.
If it STILL doesn't work take a picture that shows the connections and post

For larger more detailed images click here. No fair making fun of my dirty coffee table or my poorly manicured fingernails...

Where to buy Picaxe?

fritsl — Wed, 26 Mar 2008 09:06:32 +0100

There seam to be an echo of "where do I buy Picaxe", especially from newbees from the US.

Well - let´s make some web-shops happy out there, I entered picaxe.co.uk (http://www.rev-ed.co.uk/picaxe/), looked under "distributors" and found this most likely not too recently updated list:

International Distributors/Resellers

	UK	Revolution Education Ltd www.tech-supplies.co.uk
	UK	Rapid Electronics www.rapidelectronics.co.uk (cross-reference chart)
	Australia	MicroZed www.microzed.com.au
	Estonia	Step Systems www.stepsystems.ee
	Finland	Step Systems www.stepsystems.fi
	France	A4 www.a4.fr
	Germany	roboter-teile.de www.roboter-teile.de
	Italy	Robot-Italy www.robot-italy.com
	Spain	Didatec www.didatec.es
	Portugal	Aliatron www.aliatron.pt
	Singapore	Yuga Electronic Supplies www.memory.com.sg
	New Zealand	South Island Components www.sicom.co.nz
	Canada	HVW Technologies Inc. www.HVWTech.com
	USA	World Educational Services www.world-educational-services.com
	USA	Spark Fun Electronics www.sparkfun.com
	Argentina/Mexico	Editorial Quark SRL www.webelectronica.com.ar
	Venezuela	Plus Electronics C A www.electronica.com.ve

..And a quick google shows that there are dozens more out there:

AU:

http://www.wiltronics.com.au/catalogue/shop.php?cid=149971

http://www.dt.com.au/category.php?cat=ELECT:KITS:PICAXE

NZ:

http://www.surplustronics.co.nz/shop/cat286.html

Please add shops you find, all over the world, thanks.

Robot Hansen

jip — Sun, 16 Mar 2008 16:54:46 +0100

Primary image

What does it do?

Line following for DTU Robocup

Out of pure frustration with the fact that my LEGO MINDSTORMS NXT based robot, that was supposed to participate in DTU robocup, turned out to be crap, I thought that I'd try to at least get a decent line follower ready for robocup. This robot is based on my R/C car - an HBX Bonzer Monster Truck XTI - and it will only be able to follow a black line and hopefully also be able to handle line branches.

To start with I was going to build a line sensor based on 8 infrared detectors for 36 KHz modulated infrared light. There were some problems with that so I decided to go for 4 regular infrared photodiodes instead. It is my plan that I will estimate robot position relative to the line by interpolating values between the 4 sensors to get a smooth steering - maybe I will use PD-regulation for this if I have the time.

For controlling the car I'm interfacing the LM-406FB speed controller that came with the car. It is controlled by sending standard servo signals to it, but it does some fancy interpretation of the sequence of signals so one has to be cautious or the car maybe not work the way one intended. For steering the car I'm just using the standard servo that is in the car.

I think maybe I need to get a gear reduction unit for the car, since it goes really fast and I think the robot will be impossible to control at high speed - it tends to skid around when going fast. I'm looking at a 4:1 gear reduction unit which can be bought through eBay.

Friday 28th of March, 2008

I have made the base for the line sensor by cutting a perforated board to a shape that will fit nicely onto the car and can be held in place by a couple af screws that already hold the front bumper in place (I think I might some longer screws though since they just barely hold the board):

Now I just to populate the board with some fancy components that will make the bloody thing work!

Cost to build

Embedded video

Finished project

Number

Time to build

Type

wheels

URL to more information

Weight

Simple test with PICAXE and a monster truck

jip — Thu, 13 Mar 2008 15:04:51 +0100

Just tried out controlling my radio controlled monster truck with the picaxe. It's a simple test run of forward, turn left then right and then stop. I put the car in a spot that almost made it reach the bathroom :-). Notice how the breadboard almost flies off when the car turns... a really solid construction! :-)

I'm looking forward to making something useful out of this car... it can go pretty fast!

Dang! I can't seem to embed video in a blog post???

Well you can watch it on youtube

- Jimmy

36 KHz modulated infrared light detector

jip — Sat, 08 Mar 2008 16:59:46 +0100

I have started working on a new robot that is mainly based on LEGO MINDSTORMS NXT. This robot is aimed at participating in DTU robocup 2008 but time will tell if it will be finished in time. Anyway in robocup the robot must at least be good at following a black line and preferably it should be able to accomplish other of the tasks at hand as well, and this is just not feasible using the standard LEGO sensors and the very limited number of these it can use at one time. So I thought I'd take advantage of the fact that LEGO sensor ports can access I2C hardware (up to 127 devices on each port!) and make my own I2C slave line follower.

First off I had read somewhere that the picaxe can only do I2C master, so I figured I'd go for using the PCF8574 I/O expander from NXP since I had five of these lying around. After designing a circuit on paper I realised that the picaxe 40x1 which is the only picaxe chip I have can in fact be set to act as an I2C slave (though I have not tested this yet - just read it in the manual), so I dropped the PCF8574 since it would now be possible to do the whole processing of the line detection in the picaxe and just returning the result of the processing to the NXT when it asked for it.

The line sensor will contain 8 SFH5110-36 infrared detectors that can detect an infrared signal modulated at around 36 KHz - when a signal is detected it draws its DETECT-pin low. Also it will contain 7 infrared LEDs that will be modulated at 36 KHz by the picaxe via PWM. The light from the LEDs are supposed to be bounced back from the floor only where there is no black line.

Yesterday I made a test setup for the detector circuit on my breadboard and it seems to work kind of like I want it to. First I thought that the SFHs could only be used for ON/OFF detection but after testing it, I think maybe I can put in a capacitor on the DETECT-pin and maybe a resistor somewhere to make a potential divider and measure the voltage somewhere. I got the idea since the detection LED I put in did not just switch on and off - rather it seemed to go from off to on smoothly which I guess happened because the infrared light just barely reached the SFH so the DETECT-pin was modulated like PWM or something.

You can see a short movie showing detection of my hand here:

http://defiant.dk/movies/infrared_detector.mov

As you can see this setup can easily be used for obstacle detection as well (maybe my robot will use that as well).

Picture of the test setup:

- Jimmy

Stop burning speakers with your Picaxe chips

fritsl — Sun, 02 Mar 2008 17:06:26 +0100

On Picaxe:

sound 1, (110,3)

is NOT a good idea, you should allways write

sound 1, (110,3) low 1

(you do not need line breaks, just write it as above)

Being used to burning things and changing rechargable batteries all the time, I did not really wonder that much that a tiny speaker or two has been fried while having fun with robots and Picaxe over time (mainly 28' these are the only ones this is tested on).

Now I am building a new robot that has a speaker underneath it.. Lifting it up from a test, I felt that the speaker was burning hot!!

Picaxe is leaving the port to "High" after the "Sound" command!!! So the speaker is just getting continious voltage after a "sound".

This means battery drain, and it means burnt speakers after a while, if your robot have just at any point made a small beep!

Crap, Picaxe! (But I still love you) - Must be a bug, no? Or some reason I don´t get??

The Picaxe-boards

fritsl — Sat, 16 Feb 2008 21:09:34 +0100

Allways a board to fit your needs :)

http://194.201.138.187/epages/Store.storefront/?ObjectPath=/Shops/Store....

Arduino vs Picaxe

fritsl — Thu, 14 Feb 2008 21:15:17 +0100

Should I go for Arduino or Picaxe for my next robot?

Let´s compare:

Scalability:
******************
Picaxe run on many different chips, all from the company called Microchip.
They range from 8 to 40 pins, and is available in surface mount as well as ordinary housing
Many different pre-made project boards are available, and not only those made by "The Picaxe-people"; Control 3 servos and some ins- and outs on something smaller than a machbox, at a very small price, and up to large 40 pins projects.
******************
Arduino is possible to do in many stange ways, quite diverse, even add it on a T-shirt etc. But for robots the most applicable would most likely be the 28 pin Diecimila with ATmega168. Only this has no motor driver on it, so you are basicly stuck, unless you buy the komplete motor kit, but then..

******************
The proto board for the picaxe is valued high, it actually makes the difference - you can build a robot just by adding motors and sensors, it is robot-ready!

Picaxe: 2 points
Arduino:0points
==================

Speed:
******************
Picaxe can run from 4 to 16 Mhz, but if you plan to use Picaxe Basic, you are best off using 4 Mhz
******************
Arduino runs on 16 Mhz
******************
Although not many robotic projects will have a processor- speed-issue (or they should use co-processors if speed really did matter), and although the Picaxe can run at the same speed, Arduino wins the speed-contest

Picaxe: 0 points
Arduino:1 points
==================

Programming language, posibilities, scalability
******************
The Picaxe language is easy, yet it is quite powerful, and plenty for most robotic useage, and has a wide area of actuators and sensors directly supported.

******************
Arduino is, however, more powerful than the Picaxe set of instructions, supports floating point, is documented on how to interact with all sorts of things. But if you just want to control servos, motors, sensors etc that Robots are often made from (and not MIDI-devices, Symbian Phones etc), Picaxe is a much more focused language. To read a temperature, you will have to write dozens of lines with Arduine, do bugtracking, wiring etc. With Picaxe you merely write "Readtemp and hook up the sensor", same for servo, Picaxe is just "Servo to this and that", Arduino is several lines and configurations.

******************

Picaxe: 1 points
Arduino:1 points
==================

Building speed - time from you recieve your materials till your robot is working:
******************
Picaxe is "plug and play" - you get up and running in no time, all included. The language is so easy, your dog can code it, yet it is quite powerful, and plenty for most robotic useage.
******************
Arduino an open source project - you will spend a lot of time before you get from 0 to 100, all included, and waiting for all the packages. The language takes some time to get into, is based upon Alpha software, it is more complex than Picaxe basic, which is in version 5.
******************

Picaxe: 1 points
Arduino:0 points
==================

Number of servos controlled and other perperials:
******************
A picaxe 18 (smaller than 28!) can control 21 servos on a standard board

Picaxe uses one-liners to communicate with servos, serial, I2c and every other protocol used for typical electronics and robot-building

******************
Arduino can "only" control "up to 20" servos, and uses more complicated code for doing the same protocols.

******************
Picaxe: 1 points
Arduino:0 points
==================

OS for programing-platform:
******************
Picaxe works only on MS, although Linux is under development.
******************
Arduino is supporting Mac OS X, MS, and Linux (with some tweaking)
******************
For a wider selection of platforms, Arduino wins.

Picaxe: 0 points
Arduino:1 points
==================

Price, pre-made protoboard with chips included:
******************
Picaxe 28 pin, incl darlington & Picaxe 28X £16.01 (inc. VAT)
******************
Arduino Diecimila 28 pin incl ATMega168 £18.51 (inc. VAT)
******************

Picaxe: 1 points
Arduino:0 points
==================

Total:

Picaxe: 6 points
Arduino: 3 points

Conclusion must be that Arduino should be used once the cheaper and faster to get started with Picaxe is no longer enough for your creations, but only if you want to do some more hard-coding to peripherals and soldering yourself.

28 pin Project Board (AXE020), Picaxe for dummies

fritsl — Thu, 14 Feb 2008 11:31:34 +0100

Update: Elliot just wrote that you could use a better motor driver for the board. I have not had the chance to test it myself yet, but it sounds very interesting :)

Ground!

Often you get something that you want to connect, and the documentation says connect this to "Ground", or any other name often used in random. It has many names, that are the same thing:

Ground
Usually "the black wire" if there is a red and a black
G
GND
-
0
Vee
Vss
Negative Supply

- All the same!

This is simply where current goes to when it comes from the other pole on the battery (the positive, +).

When something can be connected to your board using "just a single wire", it allways also has to have a second wire, connected to this ground.

If you want to hook up to ground, you can use any of these connections on the board:

Also refered to in random as :

Positive supply
"the red wire"
+
Current
Power
VCC
V+
B+
VDD

Actually the reason for having a Microcontroller on a board is, that you should let the microcontroller control when you send current to something (turn it on or off).

However, quite often, you will need to feed peripherals with current (and ground, this goes unsaid), on top of what you send to it via the microcontroller.

Perhaps you are connecting a Sharp IR range finder, it has 3 wires: Black, White and Red. The black is Ground. The Red then will be V, to power the module, and the white will be a signal returning from the Sharp module to the microcontroller on your board.

Perhaps you want to control a Servo. That will also need a G and a V to power it´s circuit and its motor. And on top of this, it needs a pulse-signal from the microcontroller, the last wire - what color it may be on the perticular model.

The standard setup of the board looks like this, all these areas are V:

So - what´s with the V1 / V2?

Well, everything returns to ground. But it can come from different sources. And they can have different voltage.

This way you can power a servo with V2, while the pulses that signals to the servo where it should turn to, is from the Microcontroller that runs on V1. All to the same G.

This 28 pin Project Board has 2 options:

Standard: See illustration above. V1 & V2 are connected, resoult: There is only one V. As you may have read from the documentation: It is the little jumper in the corner that connects V1 & V2, and when it is on, there is only V & G on the board.

2 power supplies: See illustration below. Take off the jumper, and connect a seperate power-supply to V2 (and that power supplie's G to ground, goes unsaid from now ;) - and the board will have V1 to the circuits and inputs, V2 to power external stuff, and G for all of it.

That way you can feed the chips with 5V, and the motors with 12V that would otherwise kill the chips.

So if you hook up a board with 2 power-supplies, this is where you have current and ground:

.. What is left?

Only the interesting stuff! :)

Power they need, the peripherals.. But it is the inputs and outputs that are interesting.

None of the above connections can be controlled by the Microcontroller, and unless you burn something, the Microcontroller does not sense weather you connect something to these or not.

This is where the input's and outputs come into the picture:

These conect to the Microcontrollers legs. Quite often, for advanced useage, things can be altered; An input can be switched in mode, so that it is an output etc. But you will figure that out, this is just the basics, as things are wired in default:

A: The digital inputs:

Connect a switch to V1 and one of these. In the program editor you can then write (let's say you have connected to leg 4, there are 8 in this area)

If pin4 = high then

...

B: The analouge inputs

How much corrent from V1 (or another source not more powerfull then V1) comes to this pin?

Well - it is not a question i ask, but what the pin asks :)

The answer is then returned into a variable, example, pin 2 out of the 4 in this area:

readadc 2, b1

Now the variable b1 is a value between 0-255, depending on how much corrent from V1 (or another source not more powerfull then V1) comes to this pin.

C: The IR-area

This is a quite undocumented feature on the board! It is used if you want to use standard TV-remote control-protocols to send to your microcontroller.

You can hook up IR ins-and out to anything, to measure IR, for instance to see if something is near or far, or white or black.. but you will have to do with analouge levels of signal and similar, you will not be able to transmit "signals" that can be translated to numbers such as TV romotes does. Most IR remote controls use 38 KHz sub-carrier, and this area let´s you hook up to that quite simply. You should only use it for that!

D: The Serial communication

The square on the picture should perhaps include the Jackstick :) This is the serial connection used to program and more.

You can also use output- and digital input pins for serial connection, but the ones on D are hard-wired

E: Direct outputs from the picaxe

These should (only) be used if you are trying to communicate "chip to chip". I think this is called TTL-level, where you let the chips talk to each other via pulses. This should not be used to drive anything, but it should allways be used if you want your chip to talk to others, like in this example:

http://letsmakerobots.com/node/66

F: Output pins

These are what you should start with, IMHO: Connect a LED or something (Remember LED´s should turn the right way around) to one of these (other LED-leg to ground).. let´s say you connect to leg 3 out of the 8 in this area. Write:

high 3

to turn power on

low 3

to turn it off

Note that if you are using a motor controller, you should not use leg 4, 5, 6 and 7 for anything else!

These pins are also used for standard servo connection.

G: Motor connections A & B

The board is made for the typical applications, and one is where you want to control 2 motors, and being able to switch directions on them.

Of course if you only can turn things on or off, it can be hard to reverse a motor.

You can purchase a L293D motor controller - chip, and place it in here.

Then read the documentation for how to make output 4, 5, 6 and 7 control 2 way-drive of 2 motors connected to A & B outputs. (one motor to A and one to B, not 2 times A+B)

H: The reset switch

If you mount your board in a case or something, and would like to be able to remote-reset the Microcontroller, add a switch to this, press it and.. Hello? I remember nothing, let´s start all over!

How to connect SRF05 to Picaxe 28 pin Projectboard

fritsl — Wed, 13 Feb 2008 17:55:09 +0100

If you are a newbee, you may only have learned that the Picaxe 28 pin Project Board has some inputs and outputs.. And you may have purchesed an SRF05 (that Picaxe refers to as SRF005), and you are trying to connect the darn thing.. without resoult?

Reason is likely to be that you are connecting the output from the Picaxe to the SRF05 through the darlington on the board.

The SRF05 needs (like many other things) a Pulse-signal, not just a "power on / off". The signal therefore must come directly from the Picaxe chip.

Luckely the board has little "hidden" holes for that kind of conections. (Blue wire, the signal in to the SRF05 directly from the chip). These holes, however, are not described, simply omitted in the manual for the board. So I wonder how a newbee should ever find out, personaly I burned a SRF05 or two in my frustrated attempts to get it right :)

If you follow the illustration above, you should be able to make the below code work just fine. You will know that the SRF05 is getting a pulse-signal when the little red LED on it´s back is flashing red.

****

symbol trig = 3 ‘ Define output pin for Trigger pulse
symbol echo = 6 ‘ Define input pin for Echo pulse
symbol range = w1 ‘ 16 bit word variable for range

main:
pulsout trig,2 ‘ produce 20uS trigger pulse (must be minimum of 10uS)
pulsin echo,1,range ‘ measures the range in 10uS steps
pause 10 ‘ recharge period after ranging completes
‘ now convert range to cm (divide by 5.8) or inches (divide by 14.8)
‘ as picaxe cannot use 5.8, multiply by 10 then divide by 58 instead
let range = range * 10 / 58 ‘ multiply by 10 then divide by 58
debug range ‘ display range via debug command
goto main ‘ and around forever

****

Notes:

I did not have a fresh SRF05, and so there are drilled extra holes and soldered pins on the one on the picture.

Be aware that if you also connect servo(s) to the same Picaxe chip, program execution may be bumpy with little iregular breaks when using things as the SFR05 that needs pulses. If it is important for you to have a steady program execution, or if a servo acts totally irrational, it sometimes helps to have a smal pause or turn off a servos pulse for a short time in the code:

"low 3" or "pause 10". Aparently there is no system, it is just trial and error with your particular setup.

These pages might have your interest: See what Robot Sees, 28 pin Project Board (AXE020), Picaxe for dummies