0 comments on What’s CatTrack?

What’s CatTrack?

Unsatisfied with the GPS trackers available on the market, I decided to design my own.  This site follows my component-level design and build of an ultra-low-power wireless cat tracker.

A few years ago we got some cats – Buttons and Turnip!  Buttons is the big tabby cat and that’s Turnip, below.

I would imagine that every cat-owning Engineer has at one point or another wondered about either buying or making a tracker for their cat so they can see what he or she gets up to after they jump over the garden wall.

Turnip isn’t like most cats.  There’s no need to make or buy a tracker for her because she hasn’t left the garden in 3 years.  Well, she did end up in next door’s garden once, but I got the impression from the noises she was making that it was incompetence that caused her to end up there, rather than a desire to be more than 10 feet away from her bed.

Buttons however, would benefit from a tracker.  Although he doesn’t disappear for days at a time like some cats, he is often nowhere to be seen, only to turn up a few hours later covered in cobwebs or some other kind of grime.

As you can read in my About Me page, I’ve got a fair bit of experience with electronic design.   It’s been my job for the last 10 years.  None of the cat trackers on the market fitted my needs (as I’ll explain in a separate post) so I decided to design and build one that’s much better than anything you can buy! (hopefully…)

I’ll be doing a component-level design, from schematics, through PCB design and ultimately casing it all up in a case appropriate for Buttons to carry around with him.  I’m sure there will be second revision too, to mop up all my cock-ups from the first revision!

This blog is partly a way to force myself to finish the project.  I wouldn’t want the 3 people reading this to be disappointed would I!

0 comments on Comparing compilers: CCS C and Microchip XC8

Comparing compilers: CCS C and Microchip XC8

Now that I’ve got CatTrack working, I’ve been having a look at refining the code.  As I previously mentioned, I am using the CCS C compiler, basically because the ‘paid for’ version of their compiler is significantly cheaper than Microchip’s XC8 ‘paid-for’ version.  I did begin to wonder though, just how much bigger would my code be, and how much slower would it run if I used the free version of Microchip’s XC8 compiler?

This is what the Memory usage currently looks like in the PIC16LF18345, compiled with CCS C:

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2 comments on PCBs have arrived! Soldering and matching the antenna…

PCBs have arrived! Soldering and matching the antenna…

The PCBs have arrived from OSH Park!  As expected, they look good and the quality is excellent.  As an added bonus, they even fit in the case I designed them for.  Result!

Over the last couple of weeks I have also been ordering all the components from a combination of Farnell and tme.  Everything’s arrived and it’s all ready to solder into place.  I’ve also got the firmware into a state such that something should work too.

Now it’s time to get soldering!

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2 comments on Writing the Code

Writing the Code

Whilst I wait for the PCB to arrive I can crack on with writing the code that’s going to run on the PIC.  I’ll write it in C (not assembler…!), using the MPLAB X IDE and the CCS C compiler.  I much prefer the old MPLAB 8 IDE, but Microchip has stopped supporting new devices in version 8, so I’m left with no choice but to use MPLAB X.  It’s all very pretty and I’m sure I’ll get used to it…soon.

I’ve chosen to use the CCS C compiler over Microchip’s C compiler basically because of cost.  Although Microchip have a free version of their XC compiler, all of the optimisations are disabled.  This results in terribly compiled code which takes up much more space than it needs to.  Not ideal for a small embedded device with limited storage like I am using!

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1 comment on One last thing…. The Antenna!

One last thing…. The Antenna!

I was a little premature with my previous post.  I can’t quite draw the schematic diagram yet – I need to work out the antenna!

Texas Instruments have produced an excellent guide, examining a number of different types of antenna for embedded applications.  The table below summarises the pros and cons of a number of different antenna solutions and is taken from that guide.

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2 comments on Choosing a Power Source

Choosing a Power Source

The last thing I need to work out before getting on with the schematic is which battery chemistry I’m going to use.  The most important thing at this point isn’t necessarily identifying the exact battery I want to use, I need to just know the voltage, such that I can design the circuit to suit.

In order to work out the ideal battery chemistry, I need to work out how much each component draws, both in sleep mode and at its peak.

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