CC1125 – CatTrack

CatTrack 3.0?! It’s August 2023!

It’s been over 2 years since CatTrack 2.0 was “on it’s way”….

Well… umm… it hasn’t progressed much since the previous post. I’ve had some good email chats with a good guy called Robert, who has been working on something very similar over in the Czech Republic. He has made many prototypes and has shared his thoughts with me around getting decent GPS reception. In the end he has settled on a Quectel LC86L GPS module and engineered the box such that the antenna sticks out a little, drastically improving reception.

I was having some reception issues with the u-blox GPS module I was using for CatTrack 2.0, which caused me to think about making a slightly different device…

Posts 12

CatTrack 2.0 is on its way…!

It’s been a while!

The last post I made here was July 2018… quite a lot has happened between then and now. Not only did Buttons sadly get involved in a car accident and need to have a leg amputated (don’t worry he’s fine and still himself!), but I also moved house and had a child.

Also there was a global pandemic.

Anyway enough of all that rubbish, the most important thing is that I’ve been working a little on Version 2 of CatTrack.

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tl;dr complete version 1 build summary

There are a lot of posts to trawl through in this blog if you’ve not followed it from the beginning. Hopefully this summary makes everything a bit clearer…

The first thing I did was to have a look at other cat tracking products on the market. I found that they all have a big flaw… battery life. I wanted GPS level accuracy and a battery life measured in months. Nothing on the market offered that, so it was down to me to design it!

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Posts 3

Long Range Communications with the CC1125

I’ve now written enough code for the PIC on the CatTrack base station such that I can begin to test it!

I’ve already tested comms with the CatTrack collar, using a development board instead of the base station. Read about that here.

Unfortunately, when testing my base station I found that it was nowhere near as sensitive as the development board – the base station was getting CRC errors whilst the development board was still receiving the signal fine. After a small bit of investigation I found out why. The problem is all down to the fact that I want to use the CC1125 at the lowest baud rate (300 bps), and consequently a very narrow receive bandwidth (3.8 kHz).

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PCBs, Posts 1

Base station PCBs have arrived – time to solder!

Well, the boards actually arrived several weeks ago, but I’ve only just got round to doing the soldering. As ever, I’ve ordered all my components from Farnell in the UK.

All of the passive components I’ve used are 0402 sized (0.5mm by 1.0mm). The advantage of components this small is that you can squeeze a lot into the RF sections of the board, most notably at the output of the CC1125. This decreases board size and improves the RF performance. You can go much smaller than 0402 – 0201 is the next size down, followed by 01005 – only 0.2mm by 0.4mm! Getting decent performance out of an inductor or capacitor that small will be difficult, so it’s a tradeoff between size and performance.

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PCBs, Posts 1

Base Station PCB

I’ve finished laying out the base station PCB, hurrah!

As ever I’ve laid it out using Eagle – this time I’ve managed to keep it to two layers so that’ll save me some money in PCB manufacture costs. Click it to enlarge.

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Posts, Schematics 1

CatTrack Base Station Schematic

Now that the CatTrack collar is working, I’ve been designing the schematic for the base station. The base station is the handheld unit I’m going to use to communicate with the collar to work out where the cat is. Currently I’m using a CC1125 development board. More about that here.

The idea is that the base station will mostly live at home, perhaps in my loft (to get decent range) and I’ll be able to communicate with it from my living room via Bluetooth from my laptop. It should also be portable because if Buttons goes miles I want to be able to take the base station out and about to track him remotely.

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Posts 12

It works!!!

The time has finally arrived, let’s test CatTrack on Buttons.

It doesn’t seem to bother him anyway!

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Posts 3

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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Posts 1

CatTrack PCB Design

Before designing the PCB I need to decide on an enclosure to use. Ideally I need something plastic, with flanges such that it can be attached easily to a cat’s collar. Clearly size will be a big factor – I want something small, but not so small that the chip antenna is ineffective, or that it’s a nightmare to lay out and fit everything in.

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