Create Picaxe 14M2 Project Board on a breadboard!

Electronics Learner 123

Well-known member
Hi,

I recently bought a Picaxe 14m2 and project board, however my soldering iron has broken and I would like to recreate the project board using the components that I have bought on a breadboard: http://www.picaxe.com/docs/axe117.pdf . I have little electronics knowledge and I am struggling to recreate it, I understand the schematic (I think) yet I can’t recreate it, would it be possible for you to assist me with the process or even create a fritzing diagram to help me.

Thanks in advance
Electronics Learner 123
 

AllyCat

Senior Member
Hi,

Take a look (and install) the free PEBBLE software. It should allow you to show us what prototyping hardware you have and how far you've got converting the schematic diagram, etc. so far.

There isn't much formal documentation for Pebble (a very long and old forum thread) but it's quite easy to use and we're here to help. I have also shown an example in post #23 of a current thread.

Cheers, Alan.
 

westaust55

Moderator
Also please take note that the pins on the base of the stereo programming socket are not long enough to make contact on a breadboard. As such there is a need to extend the pins or use a breadboard adapter such as the AXE029 available from the PICAXE store or make your own on some strip board however that needs a soldering iron!
 

datasmith

Active member
I whipped this together using PEBBLE as an example. Note that the jumpers in the purple rectangles are placed over each other because of the limited board space. This image is slightly modified here via Photoshop to better denote the multiple jumpers. When you place one jumper over another in PEBBLE it is hard to see, especially if you place the shorter jumper first. The longer one will cover it up. I also used 0.1 inch header pins to denote connectors. I put it together quickly. Other eyes can verify/critique my layout, but it's just to show how PEBBLE works. I was recently introduced to the tool here in the forum. It's a really nice tool to have in your virtual toolbox.
 

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datasmith

Active member
PS. Ignore the two jumpers coming off of pin 1 on the ULN2003A. They are artifacts-not in use or connected anywhere. I forgot to remove them. (I'm self critiquing.)
 

datasmith

Active member
Questions in the order that I read them...
What are the two jumpers that are coming off of pin 1? Leftovers that I forgot to remove. Serve no purpose.

Is this the right way around? For this layout it is. I wanted +V and ground pins to be on the same sides of the breadboard for both chips and I wanted the 08M2 outputs and ULN2003A inputs to be on the same side of the breadboard. You could position the chips the same way but then you would have a lot of lines crossing from one side of the breadboard to the other.

What is the safe out? On the circuit diagram for the AXE117 Project board they have one of the 14M2's outputs (Out5/Pin8) also configured with some buffer resistors. This would be for some project where you would want to protect the connection to another device. This is similar to what is used on the programming input (Serial in/Pin2). It was on the schematic, so I included it. I was just trying to be faithful to the project board schematic.

Is this the right way around? See question two. Orientation is up to you.

What is this? Those are thee pins used as a connector for programming the 14M2. A Ground Pin, a Serial Out Pin, a Serial In pin. You would connect your RS232 serial connection to your computer here for programming the chip.

What is this? Lastly the big blue circle is a big ole' capacitor. I made it a big electrolytic capacitor. I guess I should have looked at the parts list, because it is actually a 100nF polyester capacitor which would be maybe a little smaller and rectangular.
 

datasmith

Active member
Concerning my three programming pins I put on the breadboard.... westaust55 is right about the programming connection. The USB to serial cable that comes with your kit ends in a mini stereo plug. I am not sure what the TX-RX-GND pin-out is for that; tip, ring, sleeve? But, if you use that cable you will need to somehow get the connections from the kits stereo jack to plug into the breadboard so you can use that cable. I don't know how you would do that without soldering wires to the jack. I showed three pins on the breadboard because I use this old OMS-U2P USB-to-serial cable that uses 0.1 inch pins that can plug directly into the breadboard. ( OMS U2P Datasheet ) Here's a picture of my cable connected to an 08M2 on my breadboard using a little ribbon cable, but if you have the space you can press it right onto the breadboard. Nevertheless, if you can't get that stereo jack connected to the breadboard (where my three pins are) you won't be able to program the chip. Now, Picaxe has this adaptor on their website that would do the trick: Breadboard-Cable-Adapter , or you could shop around for a universal usb-to-serial adapter. Maybe something like this? USB 2.0 to TTL Serial Converter Module

oms-u2p.jpg
 

Electronics Learner 123

Well-known member
@datasmith that is awesome, I have a usb ttl serial adapter so I will try and use that. Sorry to bother you more, but could you send the update breadboard with no errors because I am quite a noob at this and don't want to get anything wrong.
 

lbenson

Senior Member
Probably the best thing to do to begin to learn your way around the very useful PEBBLE program is to first download it:
pebble download.jpg
And then unzip it and play with it. Click on the images on the left, drag the resulting new image onto your breadboard, and right click on it to see the options. For instance:
Pebble examples2.jpg
For instance, if you left-click on the image on the left which begins "23R", you will get a drop-down list of all the types of boards you can use.

If you click on the LED, drag it somewhere, and right-click on it, you will get the menu shown, which allows you to choose color and orientation'

If you click on the LDR, drag it somewhere, and right-click on it, you get a long list of goodies--different components which you can place.

Click on the 8-pin IC, drag it some, and right click it to see many IC types you can choose from.

You can click on the wires to make connections.

Try out all the images on the left and you will learn a good bit about the capabilities of PEBBLE.
 

lbenson

Senior Member
I have a usb ttl serial adapter so I will try and use that
Without modification of the firmware, you won't be able to use a typical usb/serial module to program a picaxe, because its signals are "true" (idle high) whereas the picaxe programmer requires "inverted" (idle low). I have never successfully reprogrammed the firmware of one of these modules, though others have. There are several designs for hardware inverters, like these:
programmer inverter erco goeytex.jpg


(Two of these needed)
Transistor Inverter Circuit.jpg
Or if you have one of the AXE programming boards, you can simply jumper the 3 appropriate signals to your breadboard--serin, serout, and 0V.

This board I made works: https://picaxeforum.co.uk/threads/picaxe-programmer-pcb-for-ch340-gold-usb-serial-adapter.31823/
It used the first design above, by goeytex (via Erco). The zip file can be sent directly to JLCPCB.COM and they'll send 5 boards, slow boat, for $8.33USD.
 

AllyCat

Senior Member
Hi,
When you place one jumper over another in PEBBLE it is hard to see, especially if you place the shorter jumper first.
There's no need to use Photoshop (at least for that issue). At the top right of the "Insulated Wire Properties" pop-up dialogue is the option to offset the wires by 1/3 of the hole pitch (except at their un-insulated ends). Some of the "wire" options are quite complex, you really have to try them all out and learn by experience when you need them.

It doesn't look as if the OP has the "official" PICaxe programming adapter, but it's the one particular "luxury" that I recommend. If there's a problem connecting to the 3.5mm jack (e.g. lack of a soldering iron) then buy a 3.5mm extension lead and cut the end off it ! Alternatively, a "headphone splitter" (e.g. from Poundland) can be used to link two plugs; if you have a scrap set of headphones, you might try that plug, but often their cores are VERY thin. Also note that the pin connections are "unusual"; the sleeve of the plug is NOT Earth (pin connections are in Manual 1 or PEBBLE).

Finding an "alternative" USB programming adapter for the PICaxe is a real "can of worms" and NOT recommended for a beginner (particularly one without a soldering iron ;) ). Firstly, anything described as "TTL" probably will NOT work, because the polarity is incorrect for PICaxe. Secondly, it must support the relatively uncommon "break signalling", which is very difficult to identify from device specification / listings.

Cheers, Alan.
 

lbenson

Senior Member
Finding an "alternative" USB programming adapter for the PICaxe is a real "can of worms" and NOT recommended for a beginner (particularly one without a soldering iron ;) ). Firstly, anything described as "TTL" probably will NOT work, because the polarity is incorrect for PICaxe. Secondly, it must support the relatively uncommon "break signalling", which is very difficult to identify from device specification / listings.
Very true. I've probably discarded or repurposed a dozen ttl modules and "RS232" cables because they didn't support the "break" signal. But I can confirm that the CH340 "gold" ttl adapter supports break, and works with the goeytex/erco inverter PCB I made up:
picaxe ch340 programmer.jpg
 

lbenson

Senior Member
however my soldering iron has broken
Note that even el-cheapo soldering irons (like the $12 one from Radio Shack in the U.S. that I use) can be adequate. The tips are vastly better than they were a few years back. I've soldered several hundred points in the past few months, and probably over a thousand in the past year. If possible make sure that replacement soldering iron tips are compatible with HAKKO irons (the Radio Shack one is).
 

datasmith

Active member
OK, I think my fellow forum members would rather I not do all the work for you. Sooo, I have cleaned up the PEBBLE circuit diagram, dropped the unused jumpers and put in the right capacitor. But, I am providing you with the breadboard instructions in a text file. In order to see the the breadboard you will need to download PEBBLE as stated by lbenson above. Unzip it into a folder and then click on PEBBLE.html to run it.
Once it is open in your browser click on the gray button at the lower left that says "Save or Load". Then copy the instruction codes in the text file below and paste them into the window that opens up and click "Load Circuit". Then voila! You have your very own PEBBLE breadboard circuit that you can save, modify and diddle with to your hearts content. Am I being mean here?
 

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westaust55

Moderator
While I see that AlleyCat has also responded on the topic of wires on top of each other, in pictorial/visual form, using the 1/3 above/left and 1/3 below/right options will offset the wires:Offset_wires in PEBBLE.png
 

lbenson

Senior Member
I have cleaned up the PEBBLE circuit diagram
A minor aesthetic consideration: I would make the brown wires connecting to 5V red, the brown wires connecting to 0V black, the red wires connecting to the 0V columns black, all red wires not connected to 5V some other color, and all black wires not connected to 0V some other color. This can help to clearly identify the power connections.
 

Electronics Learner 123

Well-known member
I have created the breadboard, however, (on the circuit digram there are a set of three headers assigned to the stereo output), which order do these have to go into on the breadboard (does it matter).

Also, has anyone tested this out using some code to know whether this is 100% working? :)

If I wanted to use the breadboard adapter on its own how would I use it with the 14m2

Electronics Learner 123
 
Last edited:

AllyCat

Senior Member
Hi,
I don't know if this is to scale, but I dropped the stereo connector in where I had my three header pins.
No, it isn't the correct scale, the outer pins are 0.4" (1 cm) apart. Again, there's no need for photoshop, the Programming socket is in the menu list with the "Pin Header" symbol. The pin allocations are actually marked on it, although beware that the view is from the "components" (non-pins) side if working with Veroboard. In this respect the "vertical" version is clearer, which appears in both the "Terminals" and "Floating" sections. The inner pair of pins are the (unused) "Normally Closed" contacts.

Cheers, Alan.
 

datasmith

Active member
Wow AllyCat, you're right. Its way off scale. And also, this is a learning curve for me as well. Thanks for pointing this out. I keep forgetting to right-click on a placed PEBBLE item to see what all the available options are. Making space for the stereo connector requires a little more planning. Now, if the pins soldered to the connector are long enough you could probably span the socket over some of the board jumpers, but I went ahead and laid the connector out with all jumpers going around. It does require a little more board layout planning.
 

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Electronics Learner 123

Well-known member
@datasmith could you send an image of the whole breadboard, I have pebble loaded with the original but there are different wires in the image that you attached. Or could you just sent the .txt.

Thanks in advance
Electronics Learner 123
 

datasmith

Active member
I'm not near my computer right now, but you are missing a short jumper just below the orange jumper that would connect SI on the stereo jack to the junction of the two resistors to the upper right of the 08M2. I made sure that there would be no jumpers hiding under the stereo jack. I will be back to my computer later... I have an updated PEBBLE script I can post then. But it looks like you otherwise have it already done.
 

lbenson

Senior Member
I can't see where the vertical wire rising upwards from "SI" of the jack joins with the 22K and 10K junction to its left, to complete the download serial in circuit.
There appears to be a link needed connecting C30 and C31.
 

Electronics Learner 123

Well-known member
I'm not near my computer right now, but you are missing a short jumper just below the orange jumper that would connect SI on the stereo jack to the junction of the two resistors to the upper right of the 08M2. I made sure that there would be no jumpers hiding under the stereo jack. I will be back to my computer later... I have an updated PEBBLE script I can post then. But it looks like you otherwise have it already done.
Please still post it because I want to triple check my circuit
 

datasmith

Active member
OK Learner,
Attached is the circuit script. You asked about knowing if it will work. Well, that is the big question. You will need to have it do something to know if it works. So in this new circuit script I added an LED connected to one of the 14M2's outputs; B.1. ...the upper left section of the board... I am assuming that you will be powering the board from the battery clip that comes with the kit. I think it holds 3 AA's so your operating voltage will be around 4.5 volts. Thus I put a 220 ohm resister in series with the LED. The Picaxe manual puts a 330 ohm resistor in series with the LED when connecting directly to the Picaxe, but your project board has the ULN2803A Darlington driver buffer chip which will have no problem pulling the extra current through the LED, so it will nice and bright.
Now you will need to download the Picaxe Programming Editor if you haven't already done so. Configure the editor for your 14M2. Plug-in, find and configure your serial cable.
Enter this code from the Picaxe manual that will blink your LED:
Code:
main:
    high B.1
    pause 1000
    low B.1
    pause 1000
    goto main
Click on the PICAXE tab at the top of the editor. Then press Program and cross your fingers....
 

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lbenson

Senior Member
I am getting the error no hardware found on COM9
This is very common with first-time users, and the board has a great deal of experience in getting to the bottom of the problem. First things:
Clear photo of your setup.
Confirm that COM9 is correct (unplug the usb module, open control panel, device manager, find com ports, plug back in, see what shows up).
Check with your volt meter that your voltages are correct at the picaxe pins.

I Think you've indicated that you have an axe module. If so, which one? You can try plugging your picaxe chip in that and seeing if you can program that. Then swap the picaxe into your breadboard and see if it runs.
 

Electronics Learner 123

Well-known member
What is an axe module?
I still don't have a way to extend the legs on my stereo output programming socket so I tried to use hot glue and add a wire to the end of it but that didn't go very well?
 

lbenson

Senior Member
By the way, this is a color scheme I would prefer: all 0V wires are black, all 5V/3V3 wires are red, no other wires are black or red, all connecting wires are of the same color.
14example1_pebble.jpg
 
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