Newbie - assistance please - AXE118 Project Board

rogerbest

New Member
Hi - having read somewhere that the most effective way to stop my aged brain deteriorating further is to learn something new, and having an interest in programming (yes, I had a ZX21), I thought I might try to see if I can pick up the Picaxe system. This will mainly be for use on my model railway layout for signals and anything else that pops into my head, not for running locos. However, I am struggling to build the project board at present. I purchased the AXE118 20M kit, which arrived over the weekend, but cannot work out what some of the terminology means and wondered if some kind soul on here would point me towards a very simple, and hopefully pictorially based, guide to getting started. My apologies in advance if this is beneath the usual intellectual level of query for you all, but I have to confess I thought the instructions would be a little more helpful and I am truly struggling. Thank you. R-
 

techElder

Well-known member
usual intellectual level of query for you all
I seem to remember some purty low level discussion on here occasionally! :)

Welcome to the forum!

Do you think you're having trouble with the mechanics of the assembly process?
 

MartinM57

Moderator
Welcome also! I have edited your post title to make it more informative for others (you can't edit it after posting, but I can :))

As TCH really - is it the mechanical construction, what it actually is that you've built, or what to do with it now you've built it?

After the initial construction you will need:
- a PICAXE 20M2 or 20X2 - hopefully you bought one to go into the 20 pin socket
- a programming lead - an AXE027 is recommended - the most expensive part of your initial PICAXE journey
- to download and install the Programming Editor, version 5 or version 6. You may get on better with Version 5 when starting out
- and then write some simple programs - have you any LEDs...if so you can connect them to the board (ask if you don't know how, it may not be obvious) and get them flashing as a starter for 10
 

rogerbest

New Member
Thank you both for your swift responses. I have not built the board yet, as I am trying to be good and read the instructions before plugging in the soldering iron ;) Here a some of the things I am struggling with.

1. It is clear where the two larger items are sited, and which way round they are oriented as their shapes are engraved on the surface of the board. I am not so clear on the smaller items though. For instance there is a small two pinned cream jobby (polyester capacitor?). I have no idea where it goes. Is it importnat for it to be in a speciifc orientation? A picture of an assembled board would help.
2. The first instruction is "Input 0 can be optionally pulled high (use RPU) or pulled low (use RPD) ...." but how do I decide which resistor position is best for me?
3. There is reference to the ULN2803A output driver. Can you tell me what that looks? I understand about the LK1 wire link.
4. There is reference to the "darlington driver chip". Am I correct in thinking that is the smaller 18 pin plug?

On the last point Martin, yes I have a 20M2 chip which came in the starter pack.

R-
 

Circuit

Senior Member
Roger, if you look at your kit again you will see that a lot of it is self-explanatory.
Firstly, look at the "contents" section of the datasheet that came with the kit. Here you will see the listing of the parts and some clues as to how to identify them; the resistors have coloured bands that indicate their values. The circuit board is printed with the outlines of each component in blue; you just need to align each part with its outline on the board and then solder the pins underneath. If you look at the pictures on the website here, http://www.picaxestore.com/index.php/en_gb/picaxe/project-boards/axe118.html it is helpful in getting it assembled.

Perhaps if you ask more specific questions we can help you more; in the meantime I have annotated a photograph of the board to give you some idea of what goes where and how. It is just a quickly assembled visual aid to get you going.

AXE118 Board hints.jpg

A couple of further notes;
The sockets for the integrated circuits are there to make sure that you don't damage the chips themselves when soldering. The downside is that the chips can be tricky to push into the sockets without damaging the pins. A little careful tweaking inwards of the pins on the chips will help to align them with the sockets. Above all, make sure that you respect the alignment indicated by the notches on the pictures, the chips and the sockets; that makes sure that everything is the right way round.

RPU and RPL may be confusing you; this stands for Resistor Pull UP and Resistor Pull DOWN. This determines how the switches work on the input side; you can wire the switch so that it connects the respective pin to 0v (negative or ground) when you click it or to +ve.
Which you choose may not matter much for a model railway signal; in some interfaces it is important.

Tell us where you are stumbling and the help will be here.

Edit; I see that while I was creating the picture for you there has been further posting. Tell me, what sort of model railway signals do you want to operate and how do you want to trigger them? That will help in advising whether to go for pull up or pull down.
 

AllyCat

Senior Member
Hi Roger,

- download and install the Programming Editor, version 5 or version 6. You may get on better with Version 5 when starting out
Yes welcome. The Program Editor is really THE starting point, you need to get that installed and running; PE5 is "good enough" for many uses, particularly if you have an older computer (but you can install and use both PE5 and PE6 at the same time to compare them, if you wish). PE5 is a little "hidden" in the "Obsolete" section near the bottom of the Downloads tab, but still available here. It's ALL you need to get started, because it has a built-in "Simulator", so you can try out simple programs without having to worry if all the hardware is working correctly. Also, the User Manuals can be opened via its "Help" tab.

But there is a lot of information to take in, so ask here with any specific questions and very probably somebody (perhaps too many) will give you an answer. ;)

Cheers, Alan.
 

rogerbest

New Member
Brilliant Circuit, thank you. Not being very techie I work better off pictures so that is first class for me. Thanks also for your additional points, I had seen the notches in the chips and, with the aid of a strong light and a modellers magnifying glass, I have now located that very feint grey dot that gives you the common end of the in-a-line resistor part. A quick cuppa and thenn I'll have a go a putting it all together. Thanks again. R-
 

rogerbest

New Member
Thanks, AllyCat. I found PE6 a couple of weeks ago, and I have had a play with a very simple loop command. I found the simulator very helpful in ironing out the errors (bound to happen when you don't know what you are doing) of which I am sure there will be more.

Thank you all for such swift, helpful and encouraging responses. Good to find in this day and age that there are still folk around who are prepared to help others without being judgemental. R-
 

rogerbest

New Member
A couple more questions if I may.

1. Does anyone know if the AXE118 board (as supplied in the starter kit anyway) still ships with the green protective layer on the back? I read that I am to peel this off but after several Band Aids I have given up.
2. Presumably still a good idea to wipe off the board with IPA before soldering?
3. Am I correct in assuming that the pin sockets marked 0-7 on each side will also require wireing up? If not .....
4. How do the input and output devices connect to the board, assuming this will alter depending on the objective of the programme?

As soon as the light improves I shall make a start.

R-
 

hippy

Technical Support
Staff member
1. Does anyone know if the AXE118 board (as supplied in the starter kit anyway) still ships with the green protective layer on the back? I read that I am to peel this off but after several Band Aids I have given up.
I honestly don't know, and it might not always be green. It should be fairly easy to tell if there is a protective removable coating or not.

If there is, and it's proving difficult to get off; carefully putting a scalpel or knife blade under a corner should help lift it up enough to grab hold of with fingers or pliers.

2. Presumably still a good idea to wipe off the board with IPA before soldering?
I have never bothered doing that with any boards I have used.

3. Am I correct in assuming that the pin sockets marked 0-7 on each side will also require wireing up?
If you wish to use those inputs or outputs. You can either solder stripped flying wires to the board, solder in screw terminals or header pins or sockets.

4. How do the input and output devices connect to the board, assuming this will alter depending on the objective of the programme?
It's a mix of what you want to connect and what would be best for the program. In many cases it won't matter how things are wired but there can be cases where how things are connected depends on what functionality each pin has or what makes programming easier.
 

rogerbest

New Member
Project board is now built, at least partially, I am awaiting some sockets for the output terminals. I thought I had seen a programme somewhere on the main web site to test the integrity of the construction (my soldering particularly) but I'm blowed if I can find it this morning. Can someone direct me to it please, or have I imagined that? R-
 

hippy

Technical Support
Staff member
Not sure what that program would be but would guess it is along the lines of toggling each output pin and using a LED+R or meter to check that the output pin follows what the PICAXE program is doing ...

Code:
Symbol OUTPUT_PIN = B.0 ; Adjust to test all output pins
Do
  Toggle OUTPUT_PIN
  Pause 1000
Loop
Likewise to test input pins ...

Code:
Symbol INPUT_PIN = pinC.0 ; Adjust to test all input pins
Do
  If INPUT_PIN = 0 Then
    SerTxd( "0" )
    Do : Loop While INPUT_PIN = 0
  Else
    SerTxd( "1" )
    Do : Loop While INPUT_PIN = 1
  End If
Loop
 

rogerbest

New Member
I am thinking that I would like to have some sockets for the two sets of holes on each edge of the board as indicated by the black rectangles on the attached image (original kindly supplied by circuit). Can you tell me what name these parts may go by please? I can only find 2.54mm pinned sockets and it looks as though I need someting with pins twice that distance apart (5.08mm?). Many thanks, R-
 

Attachments

AllyCat

Senior Member
Hi,

They look like a fairly standard screw terminal block available from several sources. But the obvious source is from our "host" here.

They're "end-stackable", so you can make up any size (except 1). IIRC the 4 way can be split into 2 x 2, but no further, and the 3-way not at all. So sometimes you may need both types and a little maths. ;)

Cheers, Alan.
 

rogerbest

New Member
Thanks Alan - I had seen those and in fact have some in my "gash bits" box. The problem with them though is that they are too wide for two rows on each side. I'm thinking I may have to resort to soldering insome of the fly leads that came with the breadboard. R-
 

rogerbest

New Member
Success! I used the single row of standard 2.54mm sockets and took every other pin out. That gives the required 5.04mm pin seperation. You have to shave a couple of bits off with a scalpel but it all fits. Now to solder it all up and see if the blessed thing works!

Can't claim it as my idea - I asked loads of folk and one of them (from a well known on-line auction site) came up with this.

R-
 
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