Browsing Posts published in November, 2011

A piece of pizza? 26/11/11

Okay, the weather’s not as good as we’d like, but at least its not raining.  Yet.

But never fear!

Today I plan to show Sara how to light -and keep lit- the pizza oven.  She’s dead keen on learning to cook with it, so I’m obviously only too happy to show her how.

AND, as a ‘Party-Bonus’, she’s bringing a load of pizza dough.

Diane will have been to get mozzarella cheese and stuff for other delicious toppings, so late this afternoon -just as its going dark- we’re going to fire up the oven and EAT!

BUT, before all the fun, I can really feel some hard digging coming on.  There’s loads to be dug over, and it’ll be a great way to keep warm and work up an appetite.  It’ll also be an excellent antidote to all the work I’ve been putting in on the bike circuits this week.  Clear my head somewhat.

So, on with the boots and off we go.

A great day’s ‘Plotting’ ahead, I feel!

And counting. 25/11/11

I finally did it!

Okay, with a little help from undoubtedly Sheffield’s best electronic engineer, who actually said it as an almost throw-away comment; “…You have to reset everything to zero with a PIC because by default, everything is left on.”

Too true, as I finally turned OFF the PORT B analogue inputs and shazam!  Its counting like crazy.

So, in just a few minutes I have to pop back up to Diane’s office in the library to finish up the wording for a bid we’re putting together, then on my return, I will connect my circuit board up to the bike, do a little math as to how far you cycle with one wheel revolution and then, when I cycle, I’ll be able to tell how far I’ve gone.


Of course, the more cynical reader will simply say; “Why not buy one of those cheap bike computers you can pick up for less than a fiver?” And they’d be right to say this, but that’s missing the point.

The point is, without having to hack a ready-made piece of kit, I’ve actually done it myself.

And very quickly, from getting the distance travelled, I can work out all kinds of other stuff -speed, calories burned off; all manner of interesting stuff.

Yes, you can do that with a cheap bike computer, but it wouldn’t be anything like as much ‘fun’ to simply do that!

I use the word ‘fun’ there in inverted commas, because if truth be told, sometimes its been anything but fun, but I’ve sure leaned a Big Lot about the PIC interrupt system!

More soon…

Whose Cat? 21/11/11

(…am I too sexy for?)

Of course, there can only be one answer to this, namely: “My Cat!!”

Check out the blurred photo to the right, and you’ll see my prototype display showing different numbers on different digits.It works!

“SO??!!” You scream.

Ah, and therein lies the rub, so to speak.

What you’re seeing here, Dear Reader is thanks to persistence of vision (…and slowness of camera sensor…).  You’re only seeing one digit at a time.

First, the PIC puts out the ‘6’, leaves it for a millisecond, then it puts out a ‘7’ on the next display, again for a millisecond.  And so on.

Those little displays are multiplexed.  The PIC isn’t displaying all the digits at once -it only looks like it is.

AND its doing it all via interrupts -meaning the PIC is free to do other stuff -like monitor the bikes- in the foreground.

So in The Wardian Household, today there is great joy and gladness.

Now, a shower, a cup of tea, a couple of slices of toast, and then?

Well, I’ll carry on, of course!

11.55 Update.

Corrected small bug -not all the digits were counting up to 9.  A simple ‘mod’ (%10) function cured this. (‘mod’ = ‘modulus’ -remember them from school?)

Now, onto getting it to count ‘clicks’ from the bike’s rear wheel.  Then a little maths, and it’ll give an accurate measure of distance cycled.


I was right! 20/11/11

The sudden realisation last night that I’d messed up Big Style with the addressing for the seven segment displays was right.

This morning, I’ve just connected four of the seven segments with one of the digit address lines, and it worked perfectly.

I just have to connect the other three segments up along with the other three digit address lines, and by early afternoon, I hope to have all seven segments of all four digits individually addressable.

Then it’ll be Big Fun as I work on the interrupts to get it to display different digits saying different things all at the same time.


My powers of explanation are not good today, but it’ll become clear as the day goes on.

10:44 Update.

I’d made another error!  The ‘cross-piece’ of both the left hand most digits failed to light. (The middle of an ‘8’)

Turned out I’d wired some of the ‘underfloor heating’ incorrectly.

So now, it all works!

Soldering Iron: OFF

Coding Head: ON

This is where it gets really fun.



That’ll be me then, will it?

In fact, let’s all get together and shout as loud as we can:-

“Who’s the numpty??!!   WARDO!”

For the last twenty four hours or so, I’ve been kicking myself trying to figure out why the seven segment displays on the bike circuit refused to work, but not only refused to work properly, but partially worked in a really, really weird way.

I’d turn one LED on, and four would come on, one of them being much dimmer than the rest.

Then I try to turn another on, and the display would be blank.

I’d turn three on, and five would light…

Eh?  Major head-scratching.

Well Dear Reader, I’ve found my mistake.

I’m not going to go into any detail whatsoever -for fear of boring you senseless, but suffice to say, if my cat Alfie had been in, and he’d spotted it, he’d have laughed his little ratty socks off.

Its too late to do anything tonight -well past my bedtime, but first thing in the morning, you can guess what I’ll be doing.



No pizzas today… 19/11/11

…But we did cook in the new oven.

This last week, Diane has puddled a load more clay and sand, so today I really had to show willing and carry on with the oven.

Matt, Jon, Gary, David and Derek were off on another plot -clearing it for the council ready for a new tenant, so I was left up by the clay oven with Diane who was valiantly cleaning in the metal shed.  At this time of year, it tends to ‘perspire’ so everything needed a good scrub.

Today, I would make the clay ‘tunnel’ to connect the main oven to Matt’s stone archway.Before work begins.

Here you can see it after I’d cleared out the remains of the last firing before I started work, and though you can’t see from this photo, the archway at the front is free-standing.

Not for long!

Now, it had been suggested that I could just mold the clay between the dome and the arch, but being chicken, I decided to fill the entryway with sand -in a similar way to the how the dome itself was constructed.Filled with sand.

A side shot shows the kind of gap I had to bridge with the sand already packed in place.  I also put the door on the from (…you can just see it to the left of this shot…) to prevent sand spilling out of the front.

When the sand was in place and well packed down, I covered it with a layer of wet newspaper to stop the sand sticking to the clay.

Papered up.This shot here to the right shows what I mean.

You’ll also notice that I made sure there was no paper over the original dome -I needed the new clay to stick to that as best possible!

An hour or so later, nursing very cold fingers, the hatchway looked like this:-

Clay on.The eagle-eyed will notice that there’s a piece of green plastic pipe sticking out of the top of the new clay.

This didn’t stay in long!

It was simply a ‘former’ for the chimney.  I’ll confess I forgot it at first, but on remembering (…after giving myself a slap on the back of the head…), I very easily ‘screwed’ it into the wet clay and sand beneath, then left it there as I applied more clay.

When Matt and myself were putting the clay on for the dome, we used a technique of grabbing a handful of clay, then squashing it into a ‘sausage’, then laying it on top on the one beneath.

For making this archway, I simply started from the base upwards (…obviously!..), molding ‘blobs’ onto the wet newspaper, and it seemed to work pretty well.

Now, unlike a few weeks ago when we made the dome, the clay wasn’t going to set on its own -its too cold and damp.  I needed to get the sand out -very carefully- then light a fire in there as soon as possible -to prevent it collapsing.

Getting the sand out.Here on the right, you can see as I very gingerly pulled the sand out.

It all came out pretty easily, and with no major collapses, I then prepared and lit a gentle (…at first!..) fire to start to dry the clay.Fire in the hole!

Here you can see it just after it was lit, and the ‘smoke’ you can see coming off it is actually mainly steam!

Over recent weeks, we’ve had a little rain, so not only did I have to start to dry the new clay, but the old dome needed warming up as well.

Now, I wasn’t actually intending to cook anything today, but Kyle suggested that I do some potatoes because he wasn’t having any of Sara’s delicious soup.

No problem, but I warned him that I’d never done potatoes in a clay oven, so I didn’t know how they’d turn out.Spuds in tins.

In the end, I needn’t have worried.

We all agree that these potatoes, if anything, tasted better than the ones I normally do on the fire on the children’s plot.  Quite how this should be, I really don’t know, but I suspect it may be something to do with the heat being evenly applied to the tins rather than the majority being through the bottom as it is on our usual fire.  Further experimentation is definitely needed!

Also to note is that as I has the fire in there, I could only fit in one tin of potatoes at a time.  Maybe we need bigger tins to fit more potatoes?

Thats not smoke.  Its steam!

The baked potatoes were washed down with some superb parsnip soup made by Sara, and she’d brought a freshly-baked cake!  A marvellous end to a hard day’s work by all of us, I think.  I certainly won’t need any supper tonight!

Anyway, here a final ‘panoramic’ shot looking up to the oven after I’d lit it, and you can see all the steam rising from the dome.

Before I left tonight, it was agreed that Sara would make a load of pizza dough for next Saturday, then I’m going to show here how to fire this up and keep it going, and she’s going to be ‘FireStarter’ for the day.

So, make a date in your diaries.  26th November, early afternoon.

Its a Saturday, and for a change the sun is out!

This can mean only one thing:  A full day’s Plotting!

Yes, today I’ll get some photos of our new Geo-Dome and more shots of the urinals.

Also, as Diane has puddled more clay, there may well be some more shots of our pizza oven as it nears full completion.

A full day of action!

Seven Segments. 18/11/11

‘Seven Segments’ refers to the little displays I’m currently wiring up to give us a distance traveled and speed.

This is not as easy as it may sound.  Big maths, thanks to ‘C’, and the wiring is a nightmare!

I have photos I’ll post later of the ‘underfloor heating’ required to hook these displays up.

Still, its a very pretty violet colour!

Interrupts are go! 16/11/11

Just a few minutes ago, I soldered the last joint to a little ‘flying board’ I’ve built that connects into the original PIC programming board we bought all those months ago.

For reason known only to the Velleman designers, they’d put the main interrupt input pin as an LED output, but this hasn’t stopped me.  That link above takes you straight to the page of said programmer.

I unhooked the resistor feeding the little LED and connected one of the three flying leads (…the other two are +5 volts and ground…) so the new circuit was fully connected.

I then turned it on, and…


Shouts of disbelief as again and again I touched a wire across the two terminals and two LED tell-tales faithfully lit up twice to show me that yes, it had gone into the Interrupt Service Routine (ISR) and yes, it had taken notice and to prove it they lit.

Thankfully, I was fully dressed at the time, so couldn’t do the full “I’m Too Sexy For My Cat” dance routine, but this was probably for the best.  There were mothers and small children walking past, and I wouldn’t really have enjoyed explaining ISR’s and LED’s to our friends in blue ‘down the yard’.  Methinks they wouldn’t have quite understood the intricacies of it all.

So, the next step is to neaten up the code then build the first seven segment display board so when the bike wheel clicks, there’s a display you can refer to.

Of course, at first this will just be numbers that don’t actually mean anything, but very quickly -thanks to the math routines embedded within ‘C’- I’ll be able to make it display in Kilometers.

Then its the small matter of providing a speed output, but as that involves using the timers on the PIC, well, that’s for another day I feel.

In the meantime, the Wardian Household tonight is a happy place, and Heaven knows, we need all of those we can get right now.

More soon.

PIC-ing like crazy. 16/11/11

You may have wondered just what has happened to the much-trumpeted project of a few months ago; namely the Plot Power Project and the electric bikes we were getting all in a fizz about.

Well, Dear Reader, you can wonder no more!

Now the growing season has just about finished and the utter circus that was Allotment Soup is finally out of the way, along with those three major projects, I’ve gone back to the bikes with renewed vigour.

Well, I think its vigour, because once again its keeping me awake at nights.

‘So whats the latest??!!’ You scream.

Well, things have definitely moved on.

Whereas before we were using PIC assembler language (PIC ASM), now we’ve had to move on to ‘C’ for the PIC.

We’ve had to do this because the maths required has just leaped up a notch as we implement the distance traveled and mean speed functions.

For those not in the know, assembler is the real nuts-and-bolts, individual bits and bytes control; ‘C’ allows for more ‘English’ looking and reading code.

For those of a certain age, it looks and reads a little like the BASIC of old so favoured by the BBC B and ZX81 micros but with added refinements.

There were, of course problems with this.

Firstly, getting the ‘C’ compiler to bolt-in to the Microchip Integrated Development Environment (IDE) was a nightmare.

Then, there was the problem that Hi-Tec who produce the compiler have released virtually no how-to manuals, so you’re on your own!

Anyway, I’ll not bore you further dear reader until I have some pretty photos of it in the coming days.

Suffice to say, the other night, I got an LED to flash with a ‘C’ program, so now I just have to get the interrupts working, and we’re away.

So close, and yet so far…


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