In Practice

A project log for DWM1000 Cat Tracker

Using the DWM1000s amazing ability to pinpoint tags to within 10cm we will track the cats positions in the house with amazing precision.

dryerziniaDrYerzinia 06/28/2016 at 05:020 Comments

After setting everything up and getting the tags on the cats I periodically went and found them to make sure the system was working. By watching them move around on the screen I found out some interesting new places they like to hang out. For example I found out Fiona started sleeping in my parents bathroom closet while my sister was in China.

What a silly kitten.

And I also found Jasper hiding under the bed. I would have never found him if he wasn't wearing the tracker. Even knowing exactly where he was because of all the crap under the bed I had a hell of a time spotting him.

I even set up a Raspberry PI to display where the cats where in the house in the living room so anyone in the house could have a quick look and see where they where.

I thought this would be a good place to mention why I put all this effort into tracking the cats. With my grandma in town for a few months and her prepensity for leaving the doors open as well as the many Coyotes roaming the open space around the house its necessary to know where the cats are to keep them safe.

The battery life is quite excellent with the 400mAh I am using. You can see the tag in the background here. The battery is about the same size. A bit big for the cats but based on measurements of the voltage over the time the cats have been wearing them it will last 106 days. Charging batters once every 3 months is a pretty good timescale I think.

The standby power was measured at 70uA. I am considering using a external timer to trigger the beaconing instead of the internal RTC and I could maybe get that down to sub 1 uA. Based on the battery voltage drop the overall current consumption is 330uA. So the device averages out to 260uA of operating current with its 30 seconds ranging cycle. Using an external crystal for system stability and increasing the SPI clock speed up to 16+ MHz should let me do the ranging in about half the time hopefully dropping the average beacon current consumption to 130uA. This would either result in a much longer battery life, or i could make the beacons come closer together, use a smaller battery or a combination of all 3.

As I mentioned before the current size is quite huge because the home made single sided PCB, but I have plans for a much much smaller board.

You can see I went a bit crazy and used a chip scale package for the processor. Its basically at the size of the DWM1000 module now. Tune into the next project log to see how the super minature tag works out.