GPS, Sensors & Microcontroller

[jsluke]

Hi

20 years ago I completed a degree in electronic engineering, however I was seduced towards software engineering. After a long break I've dug out my soldering iron and started a hobby project. As I'm very out of date I would really appreciate any advice or suggestions.

My project is to build a telemetry data logger for a Go-Kart. I've been given a GPS (GPS Module with onboard Antenna GPS-622R) and I would like to use a microcontroller to take position data from the GPS module and store it to memory. In addition, I would like to capture 3 channels of analogue data - pitch, roll and throttle. Finally, I would like to transfer the logged data from the data logger to a PC via a USB cable.

I'd appreciate any comments on the above and in particular on the following questions:

1. any recommendations on the selection of the micro-controller - I've been looking at the PIC16F627 as I can pick up a relatively cheap programming kit from Maplin.
2. any ideas on sensors to measure pitch and roll?
3. any suggested reading on the USB integration with a PC? This is the real unknown area for me - I've integrated sensors and microcrontrollers before (albeit 20 years ago) but I've never worked with USB.

Any thoughts on the above would be very gratefully received.

Many thanks.

James.

[Simon (Webmaster)]

Hi,

A couple of quick answers:

1: Go for one of the 18F series of PIC micros, or the 30F / 33F if you need more power. They can be programmed efficiently in C and have a good range of peripherals built in.

3: Leading on from this, PIC micros with USB are available complete with free USB stack firmware and drivers from Microchip - see www.microchip.com/usb. Again the 18F series have USB versions (I've used the 18F2455 as a USB - serial converter, more powerful ones are available), I think there are 30F / 33F versions too. You need to start with the USB stack and add the rest of your code to it - trying to integrate the stack into an existing project is a bit of a nightmare.

Not sure about 2, some sort of gyro I would imagine, but there might be simpler / cheaper options.

[jsluke]

Thanks Simon for the reply and the pointer on the PIC and the USB integration - I'm looking into that now.

On the subject of the tilt sensor, I've found a couple of electronic gyros - typically they're priced around £40 so quite an expensive component. I don't require a high sampling frequency so such devices could be overkill. I'm considering mounting a series of mercury tilt switches at different angles, however that seems like a very crude solution and I suspect it might not be very reliable.

James.

[Simon (Webmaster)]

There must be something quite common now since a lot of smart phones have motion sensors in them. Mind you I suppose they are using them in large enough quantities to get the price down. Thinking about it, I think it's accelerometers that are used in phones - might be worth looking into them. Tilt switches could work depending on how many angles you need to sense.