GPS - Picaxe Vario ?

[cncoz]

Surely someone knows if this can be done.
I fly FPV but can't afford a OSD system but it would be nice to have some idea of altitude or rate of climb/fall etc.
I've got RS232 GPS and I've got some Picaxe 08M's and a programmer.
Do you think it's possible for a picaxe to get data from the GPS, do some calculations then output beeps (like a vario perhaps) that can be sent back down the audio of my 2.4GHz transmitter where I can listen to what it's doing ???
Any advice/ideas ?
Thanks all !
Graeme

[Ron W3FJW]

Here's an inexpensive OSD.
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8304&Product_Name=Eagle_Tree_Video_OSD_Expander_

[cncoz]

Here's an inexpensive OSD.
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8304&Product_Name=Eagle_Tree_Video_OSD_Expander_

Thanks Ron, had a look and got all excited, but by the time you get the datalogger or elogger and gps adaptor board that you aparently need to get the OSD expander working you're looking at $265.
Or have I got it wrong ?
Cheers !
Graeme

[Ron W3FJW]

Dunno Graeme. I've been buying ET sensors, equipment, etc. over the past year. Never kept a running account on how much the gear cost. HC is still the place to get the best price. I bought the OSD from ET before HC had it in stock. Paid about $15, $20 more for it. From all accounts, ET gear, where ever you get it is well worth the price. Support from what I hear is very good as well.

[vpatron]

Graeme, I don't know much about Picaxe; I use the PIC chips directly either in assembler or C, but it should be possible.

It may not be fast enough to generate the tones using software, but you should be able to modulate an audio oscillator circuit so that for example the beep-beep rate varies with altitude or with how fast it is losing or gaining altitude.

You'd have to learn about NMEA sentences and write code that decodes that stuff.

-Vince

[cncoz]

Thanks Vince,
I've been looking at NEMA sentences, there's a few examples of GPS altitude loggers using Picaxe I've downloaded and looked at. I'm confident the picaxe will handle the beeping bit, I was thinking of doing something a bit different so I can get altitude as well as climb/fall.
If I did the altitude in 3 digits (metres) like , 2beeps, 3beeps then 5beeps then a pause for 235 Meters.
I could use a low tone for falling and a high tone for climbing.
Anyway it looks like it's gonna work. Maybe burn the picaxe and do some tests on the weekend.
When funds becone available I will put a LCD "dashboard" on the plane to display the data (in front of the camera), then down the track I can look at OSD conversion.
Anyhow,
Thanks,
Graeme