A very simple problem - but I don't know the answer!

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robert.higginson

New Member
Please bear with my request as I am new to this and so not at all good.

I have successfully used and program the various project boards and want to create similar (but simpler) on a breadboard to control a simple 3v toy motor, a LED, and a LDR using a 18pin PicAxe (18M2). I know that this might be overkill but it is the chip (18pin) that is used in the buggies and T4 project boards so I would like to keep things the same. The breadboards will all be powered by a 3x1.5v battery pack.

I have no background in electronics (only 20+years programming) but will have to teach a unit concerned with micro controllers and so am trying to teach myself and create some step by step material before next term and make it interesting and practical. I believe that I should use a L293D to control the motor (?) forward/reverse action.

Is there any way that anyone could give :)confused:) me any help of laying out a breadboard for this circuit including the programming circuit, or suggest somewhere I could seek help. I have ‘Googled’ my way through the internet and looked at these forums but cannot find anything that I understand and can use as I cannot find an ‘Idiots Guide’ or reply. I think one of my problems started with the diagrams I am following (section1/page 33 of the manual) but it does not seem to use the 3.5 jack and so I am stuck where the 1-2-3 pins are located.

Hopefully there is someone reading this who will take pity and help me out and explain things in a simple way suitable for an 'idiot' - I would be thankful for any help.
 
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SAborn

Senior Member
Do you mean there is varing degrees of idiots amonst us other idiots. :D

Not exactly what you have asked for, but here is a schematic using a 08m and a L293B motor driver chip.

It was designed for running a stepper motor, but you could just add a dc motor where one of the coils is shown. (Or up to 2 dc motors.)

It might give you some idea of setup to help you understand.
 

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John West

Senior Member
Have you looked at the circuits shown in PICAXE Manuals 1 and 3? They are quite helpful. We can answer a plethora of questions, but we'll need you to be a bit more specific. Those two manuals are an excellent starting point for someone who is new to the hardware end of things.

By "breadboard" do you mean a "plug in the wires" bd layout, or a solderable bd, or what?

There are at least a couple of PICAXE experts who support this forum who are also educators, so I'd suggest you've come to the right place for such help.
 
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scoop

New Member
You need to do it step by step and build up your circuit.

Look at page 33 in manual 1 and that shows the basic circuit for an 18M2. The 3.5mm jack is shown on page 8 in manual 1 and if you trace the connections you should be able to see that Serial Out is connected to pin 1 on the three pin connector and pin a on the jack. Serial in is pin 1 on the connector and pin b on the jack, and that leaves pin 3 which is the same as pin c on the jack.

Once you have that add bits on one at a time. For example you could add the led using manual 3 page 9 but note that just because it says pin 1 on the diagram doesn't mean you should connect to pin one, use any output pin you want to. Once it is added then you can write a simple bit of code to see if it works.

Add the motor using manual 3 page 12 and just carry on adding one part at a time and testing each time.
 
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robert.higginson

New Member
Thanks for all of the info.

I have studied the manuals - but the main problem is a simple one - I am using the stereo jack socket and not the three pin header. Stupid question - which pin is which and which way up are diagrams drawn - looking from the top or the pin side (what do the little x's mean on page 8/section1). What I am attempting is the programming part first then as you suggest add the LED etc one at a time.
I haven't downloaded the Pebble software yet but will it sophisticated enough to tell me if the circuit is viable as a 'programming circuit' - a tall order - or is there an example I can download?

Again my question is of a very basic nature - and thank anyone for any help they can provide.

:) Robert
 
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MartinM57

Moderator
Picaxe Manual 1 version 7.0 06/2010 (yes, I think it's a slightly old version) bottom of page 7 clearly says "Above View" right next to the jack socket.

And it shows how the parts of the jack plug relate to the socket.

So what's the question? (apart from what the little x's are - I've no idea :))

EDIT - and no, PEBBLE won't tell you if you have a viable circuit - it is just a layout tool.
 

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lbenson

lbenson

Senior Member
What is it that you find unclear about the circuit on page 8 of manual 1?



"c" is the tip, 0V

"b" is the middle, serin

"a" is the ring farthest from the tip, serout.

The socket diagram is a view from the top.

"x" can be ignored.
 
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Tricky Dicky

Senior Member
If it is just a case of constructing a Picaxe circuit on a breadboard and only having a download lead with the 3.5 stereo jack, the simplest solution is the AXE029 breadboard adaptor. This has the jack socket and the download circuitry built in and only needs the connecting pins to be correctly aligned with the Picaxe 18M2 pins, do however leave the adaptor in place after a download without the two resistors the Picaxe will behave in unpredictable ways.

What age group are you planning to deliver this unit to? I ask this because if it is to school age pupils you may not want them inserting/extracting the Picaxes from the breadboards this soon leads to many bent and broken pins. Using some of the ready made project boards may be a better option. We breadboard our circuits but have the picaxes mounted on "daughter boards", these PCBs have all the download components mounted on them and using pins simply plug into the breadboard. The remainder of the breadboard is used to construct the input and output circuits only. If you are interested I can give you details of the Picaxe 18 board we use PM me if want further details.

Richard
 
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robert.higginson

New Member
The age of the students will be approx. 16years. Most however will not be mature (I'm being polite). The unit is really just concerned with theory is usually simulated - not anything to do with actual electronics. For my sins I thought that actually doing it would be a good idea for me to get to grips with things. I have several 'toy kits' acquired over time that have simple 3v motors and so I thought 'lets convert them'. I already have purchased lots of T4, school experimenter boards and buggies and can program things to happen with them with ease. This project just to make things fun by using simple toys as well. I am not an electronics expert by know my way CISCO and IEEE courses. All I need now is a kick start in the right direction - Thanks
 
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