PicAxe Teaching System

bhanlon56

New Member
There are a number of threads on this forum regarding development systems.
This is a teaching system. Its for teaching basic circuits and Picaxe programming not developing a project or application.
Its offered simply as a starting point for teachers.
To give context its aimed at students who attend University of the Third Age (U3A). These students are retirees. The course has zero budget; this may change in the future but at present I'm recycling what I have.
The course is structured around "How Does a Washing Machine Work" as a focus question, so we'll look at LED's (the display), switches, buzzers, thermisters (water temperature control), LDRs (to measure water turbidity) and motor control. The course goes for an hour a week for 8 weeks.
The photos show how I've set it up.
Its based on a breadboard that is bridged in the middle with a 18pin socket. Links between the socket pins and a female header join the two halves of the breadboard. The Picaxe 08m2 pcb shown mounted in the header has the programming resistors and supply decoupling capacitors. The board uses the socket as a bus that brings out the power supply and pins c.0 to c.4. It has a diode to protect against reverse supply connection.
Each device used has its own bus made of male pc headers. The first photo shows the LED board. My students need only match the right hand side pins and the board is correctly wired to power, c.1 and c.2. This minimizes errors due to failing eyesight but for those that can, the circuit can still be traced out. Using c.2 also allows me to introduce pwm.
The bridging socket allows breadboard space to use multiple device boards, for example using an LDR to control the lights.
I used pins c.0, c.1 and c.2 for output devices and c.3 and c.4 for inputs with the exception of the motor board.
The second photo shows my motor setup. I'm using MX1508 motor controllers to drive two 4.5V motors. These are used with my kids/grandkids lego to make a simple robot. Again, the connecting matrix board has a bus made of male pcb pins that match the Picaxe board. The MX1508 uses pins c.0, c.1,c.2 and c.4. It leaves c.3 for a switchable input.
Its a real limitation. The current solution is to use a second picaxe board connected via a serial connection. The main advantage is that I have the boards.
However I'll build another set of Picaxe boards using a 20m2 based on a design by @lbenson. It should be possible to bring out port C to a bus so that it matches the 08m2 port C so I can reuse my existing device boards.
Finally I cut off the axe027 audio jack and soldered the wires to the same bus as the picaxe board. Again, by lining up the right hand side pins, the correct connections are made.
Cheers.
 

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manuka

Senior Member
Interesting idea,& I'm a great breadboard fan, but best factor in that many seniors (your assumed U3A clients) indeed have vision & tactile difficulties that may limit their use of small items... During my educational work with PICAXEs 15+ years ago I developed a "snap circuit" approach that was well received by youngsters & seniors alike. US firm Elenco has since enhanced this idea enormously => https://www.elenco.com/discover-coding/
Stan. in NZ
 
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lbenson

Senior Member
Looks good. Did you fab your own one-sided 08M2 PCBs?

I think including kinetic parts like your motors is an excellent idea. Micro servos would also give an opportunity to wave the flag, or pan a camera.

For any who want to push further, the 37-in-one sensor kits offer much opportunity to play.
 

bhanlon56

New Member
@manuka
Absolutely if my local U3A could afford them. The current course is over-subscribed. But from the management committee's longer term perspective they would be concerned about buying gear based around one teacher. Its how I ended up with the parts. When I retired from my school the course stopped as they had no teacher with the interest. In 40 years of high school teaching I ran across one other teacher interested in electronics.
By the way, it was your series of articles in Silicon Chip that got me into Picaxe. I was teaching electronics elective courses in years 8-10 and always looking for projects that fitted my $40/student/year budget. So a very belated thanks!
@lbenson
Saw these. Was the inspiration for what I did. The PCBs were made by JLPCB. My first commercial pcb. I've used Kinsten photosensitive boards mostly. Explains the 1.25mm track widths. I use Kicad for the design and, after seeing your gerbers, feel seriously amateurish! For simple boards I generally do a quick layout in Kicad or Peeble and then use this product
@erco
"Free shipping". Had a second look. The supplier offers tracked shipping included in the price so it is a good deal. Its amazing what you can get from China but untracked shipping (to Australia) in my experience is a bit hit and miss. Tracked is also faster. I think untracked goes via Austria :)
 

lbenson

Senior Member
I use Kicad for the design and, after seeing your gerbers, feel seriously amateurish! For simple boards I generally do a quick layout in Kicad or Peeble and then use this product
I'm strictly an amateur, but thanks. I've probably done 4-5 dozen PCBs, and practice makes . . . well, practice makes for improvement.

I used a bit of protoboard today--trying to make sure the design works for a current transformer AC on/off sensor before sending off to have JLCPCB make boards. I use EagleCad. If you think the schematic and board files for the 20M2 PCBs might be of use to you, I can zip them up and post them.
 

manuka

Senior Member
"By the way, it was your series of articles in Silicon Chip that got me into Picaxe. I was teaching electronics elective courses in years 8-10 and always looking for projects that fitted my $40/student/year budget. So a very belated thanks!"
=================================
Modest blush - I'd a good decade with SiChip articles before senior eye issues, retirement & other projects intervened so glad you fired on my enthusiasm. Where in Australia are you ?
Mmm -although ~15 years back (& now tending e-quaint ! ) the "Snapped PICAXE" was popular & very DIY doable. Students often bought their own kits (~Aus $15) & kept them after conversion. The approach featured in a SiChip article but perhaps its worth rustling up as a fresh Instructable?

Extra: Excuse my expansive response BUT given your U3A needs (& $0 budget...) trust it's of benefit. Stan. -Wellington,NZ
 

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manuka

Senior Member
Typical user setups resulting.We later added an internal IR receiver at PICAXE Pin 3 to allow remote control! This was all before smartphones & widespread BT use.
A power strip was useful for driving lamps etc.
I even persuaded the setup to send SMT (Sequential Multi -Tone) Hellscrieber =>
Although popular with youngsters I was then teaching first year University electronics & one student -typical of many with little hands on e-experiences - commented "I've picked up more in an hour with these than in a week with ######" !
 

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bhanlon56

New Member
@lbenson
I have your designs. You pm'd them to me. Thanks again. I build on the copper side using through hole components. Its a hangover from teaching where my students would make the pcb and then break upteen 1mm drill bits drilling the holes. Having the tracks and parts on the same side also reduced placement errors. Your silkscreen layer makes for a professional finish though.
@manuka
Newcastle.
Would have been a great system for my year8 students. We started with the patterns at the back of the funway books. Instead of using the spring connections we hammered nails into wood and soldered the parts to the nails. It sounds prehistoric (it was) but it taught soldering skills in a hurry. I'm actually a science teacher (or was). I always tried to do prac work. My students may not have learnt as much content but I'm sure they left with a positive attitude towards science.
 

manuka

Senior Member
Top marks for effort - boys often prefer "learn by doing" tactile involvement.
 
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erco

Senior Member
I'm also ramping up to resume teaching electronics & programming Picaxes using these handmade breadboard boxes. Powered by an internal Lipo power bank and each has a built-in voltmeter. Same box as used here:


Here's a small class of friends from a few years back:


I've been stockpiling cheap laptops, soldering irons, tools, etc. My latest hoarding prize just arrived today, I bought up the last of Newark's cute Velleman micro multimeters for just $3.26 each! IIRC Velleman is a British brand, so they should work just fine on PICAXEs on this side of the pond.

NYAE4411.JPG
 

bhanlon56

New Member
@erco
Nice meters. You must have a way bigger garage than I have! You have also alluded to a concern I have. I taught 3D printing first term here with U3A. Had an amazing variety of laptops. I was using Tinkercad and one student had trouble as her laptop had never been connected to the internet so had never been updated and Tinkercad refused to run. Other with macs and different flavours of windows. I was going to use axepad so we had a common base but I believe newer macs won't run it. We may have to use picaxe cloud which is doable at my level. Installing the axe027 driver is always a pain. Its one of the selling points of arduino (and cheap chinese boards).
 

manuka

Senior Member
Back in my active PICAXE era I became so peeved by student's "old laptop" woes with costly AXE027 that I eventually sourced dirt cheap alternatives that "always worked". They seem still available (here in NZ anyway) for ~US $2. Stan.
 

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manuka

Senior Member
I'm also ramping up to resume teaching electronics & programming Picaxes using these handmade breadboard boxes. Powered by an internal Lipo power bank and each has a built-in voltmeter. Same box as used here:


Here's a small class of friends from a few years back:


I've been stockpiling cheap laptops, soldering irons, tools, etc. My latest hoarding prize just arrived today, I bought up the last of Newark's cute Velleman micro multimeters for just $3.26 each! IIRC Velleman is a British brand, so they should work just fine on PICAXEs on this side of the pond.

View attachment 24782

Great little DMMs ! I came up with an auto power off FETlington feature that's worth doing =>
 

lbenson

Senior Member
Back in my active PICAXE era I became so peeved by student's "old laptop" woes with costly AXE027 that I eventually sourced dirt cheap alternatives that "always worked". They seem still available (here in NZ anyway) for ~US $2. Stan.
I'd be wary of those. Probably only a third of the ones I've bought over the years have worked, and some of the working ones quit working with driver updates. Nominal PL2303 are particular culprits (because knockoffs).
 

manuka

Senior Member
Sure -"fakes" existed but were readily ID'd. I bought boxes of the "goodies" & gave them away when hassles arose. Note - this was a good decade back when most old laptops ran WinXP or even Win98.

These days most micros of course use direct USB -mini/microUSB (B.A.S. I.C. friendly Australian Micromites are typical).

OTA (over the air) linking via WiFi or BT/BLE & smartphone (BBC micro:bit style) looks the way ahead, especially since most folks are now familiar with such technology !

FWIW www.picaxestore.com still lists a 3rd party sub GHz ERF/URF OTA approach, but I believe these have l-o-n-g since been discontinued ...
 

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erco

Senior Member
For DIY serial/usb adapters, I'm still a fan of @Goeytex's mad genius at https://picaxeforum.co.uk/threads/problem-with-downloading-the-program-onto-the-picaxe.18715/#post-174475.

I have built ~ two dozen programming cables using his inverter method and $1 serial-usb adapters, both cp2102 and ch340g versions. Both work perfectly with win10, although there was a brief Silabs driver hiccup a few years back. Goeytex advised me some years later to ground all unused comparator inputs to avoid oscillation. I do that now, but the first dozen I made without doing so have always worked perfectly.

And thus his fears were (wait for it)...




ungrounded!
 

erco

Senior Member
That 2N7000 auto-off is pure genius Stan! I have a pile of those and will definitely try that and some of your other great meter mods!
 

erco

Senior Member
I'd be wary of those. Probably only a third of the ones I've bought over the years have worked, and some of the working ones quit working with driver updates. Nominal PL2303 are particular culprits (because knockoffs).
Yes, Prolific 2303s stopped working when Win10 came out. They worked fine up till then.
 

erco

Senior Member
I buy 10 or 20 off Ebay China, still using DIP modules myself. https://www.ebay.com/itm/402845497200

Prices are up and free shipping is rapidly disappearing on Ebay. I've started using AliExpress more than Ebay since they started taking Paypal. Pics of my rig attached showing how it plugs into my breadboards. I wrap the 74HC14 with electrical tape or shrink wrap to protect the white wires, just removed for these pics.
 

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erco

Senior Member
I'm hoarding amassing quite a multimeter collection for various upcoming classes. I actually love the tiny analog meter in the lower pic on the left. Accuracy, repeatability and readability are poor but that moving needle is satisfying, and I think in a few situations a rapidly swinging needle might be more readable to show trends than a digital display for students. Hey, it was only $1.43 USD from AliExpress, plus shipping. Got 5 for $17. Here's a scathing review:
 

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manuka

Senior Member
Yes indeed "You can never have too many multimeters"! As a 1960s teen I recall my first analogue one cost -sigh- almost a weeks wages ...

The weakness with these modern DMM cheapies is usually their mediocre leads and lack of auto power off,which peeves when their small 12V battery is found flat AND also contributes to switch wear or incorrect settings. The latter is particulately irksome with "knob twiddler" users... Some DMMs are bright light sensitive too ! I addressed issues with a FETlington slanted Instructable => https://www.instructables.com/Mini-DMM-enhancement/
 
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papaof2

Senior Member
There are times that an analog meter is more useful than a digital meter because it actualy more-or-less keeps up with the voltage or current fluctuations as the load changes. Simpson 260, anyone?
 

manuka

Senior Member
Getting back to the original "teaching/hour of code" topic reminds me that if BASIC is going to be taught (rather than more modern uPython etc) then insights can gained via an Android app. Google's Play store offers the free "(RFO) BASIC!" that's very well thought of - all learners need is their Android smart phone!

Extra: My 2007 era "Snap PICAXE !" Instructable is now dusted off & reloaded -perhaps for fresh users? => https://www.instructables.com/Snap-PICAXE-/

Stan. in Wellington,NZ
 

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tmfkam

Senior Member
I recently bought a meter from AliExpress. It has a Li-Ion USB rechargeable battery, backlight LCD display, four digits readout, torch, hard rubber case, that is pretty much standard. What it does which amazes me is that it will automatically and seamlessly detect DC volts, AC volts and Ohms. I can place it on a DC source and it displays DC volts, stuff it across AC mains, AC volts shown, across an unpowered resistor, Ohms shown, straight back to 240V AC, volts shown, move to the rectifier, 340V DC displayed. All automatic, no range changing required. Magic!

All for £22, shipped. Bside S11 should locate it.
 

manuka

Senior Member
Magic indeed -more a smartphone than a DMM ! Probably not the best for learners as it may remove the crucial electrical need to THINK about what you are doing -somewhat akin to hunters needing to identify their target before shooting...
 

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erco

Senior Member
Love that "S10 smart muitimeter" (sic). Chinglish and Japanese English phrases get me every time! Seriously, that's an amazing meter. Adding to my wish list.
 
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rq3

Senior Member
There are times that an analog meter is more useful than a digital meter because it actualy more-or-less keeps up with the voltage or current fluctuations as the load changes. Simpson 260, anyone?
And an analog meter actually draws some current. Some years ago, after an exciting flight in a friends Beech-18 twin egine aircraft, in which the landing gear wouldn't extend, he showed me the troubleshooting he had done with his digital DMM on the landing gear switches. The DMM had an input impedance of 10Mohms. The switches all looked fine.

I winked at him, and did the same checks with an antique Simpson analog ohmmeter (input impedance 10Kohm). Two of the switches failed. They could carry the micro-amps required for the DMM, but not the milliamps required for the analog meter. Let alone the amps required in actual use.
We replaced the switches, and no longer had to use the emergency, hand crank the landing gear, process. A two man operation.

He was a fully qualified aircraft mechanic, and sadly died in a P-51 crash a while ago. I miss him very much, and think of him whenever someone thinks that the latest-and-greatest technology will solve all issues. A Digital Multi-Meter may be your worst enemy if you intend to draw any appreciable current from the circuit.
 

papaof2

Senior Member
All about knowing which tool is appropriate for the testing you are doing. For switches, I like a test light with a bulb that draws about 100ma - no question whether the switch makes good contact.
Some of the DMMs have a "continuity" test which does pass more than the microamps needed for the 10meg DMM.
 

John West

Senior Member
And an analog meter actually draws some current. Some years ago, after an exciting flight in a friends Beech-18 twin egine aircraft, in which the landing gear wouldn't extend, he showed me the troubleshooting he had done with his digital DMM on the landing gear switches. The DMM had an input impedance of 10Mohms. The switches all looked fine.

I winked at him, and did the same checks with an antique Simpson analog ohmmeter (input impedance 10Kohm). Two of the switches failed. They could carry the micro-amps required for the DMM, but not the milliamps required for the analog meter. Let alone the amps required in actual use.
We replaced the switches, and no longer had to use the emergency, hand crank the landing gear, process. A two man operation.

He was a fully qualified aircraft mechanic, and sadly died in a P-51 crash a while ago. I miss him very much, and think of him whenever someone thinks that the latest-and-greatest technology will solve all issues. A Digital Multi-Meter may be your worst enemy if you intend to draw any appreciable current from the circuit.
I repair test and measurement equipment, and I learned early on that understanding what a meter is actually measuring, (instead of what the indicator indicates,) is the most important aspect of using a meter.
 

erco

Senior Member
do
pwmout 2,99,0
pause 800
for w0=0 to 400 step 2
pwmout 2, 99,w0
pause 10
next
pause 800
for w0=400 to 0 step -2
pwmout 2, 99,w0
pause 10
next
loop

 
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