As maybe some people noted, I work on balloon trackers. I will give a little introduction:
Balloon trackers are devices which GPS position can be remotely tracked by a radio link. It's actually not a new thing. Amateur balloon got quiet popular since 2000. But the payloads have been quiet heavy. >250g. So it was only possible to attach payloads to large Latex balloons which will eventually burst at high-altitude (30km) and come back to earth within few hours.
The Pecan Project came up around 2008 by a friend of me (Thomas KT5TK, he not on the Forum). He wanted to build a tracker which is much smaller and can run on a single AA-battery having a weight less than 20g in total. So he was able to put this tracker to a much smaller foil balloon. Foil balloons (or also called super pressure balloons) are kinda special. They can last up in the air for very long times (weeks, months, maybe years?). By using this fact it's possible to travel huge distances with one balloon. We've flown a balloon last year over 9 days around Europe and Asia.
In the end of last year (2015), we wanted to go further. There are camera balloons available but usual solutions with RasperryPI's still weight around 150g. We wanted to get something smaller and more power efficient. So Thomas came up with the STM32F4 series and with a OV9655 camera demo board. We've spent a lot of time into the camera because we wanted to get sure, we can operate a camera without any external RAM (because external RAM takes power, money and more effort to build it).
I knew it would take a lot of time to implement all the features. So I've chosen ChibiOS because I already worked with it at my old company. I have been quiet impressed, because there has been no need to implement any drivers (except of DCMI). I saved a lot of time. We have a lot of features which I have to organize somehow. So I don't want to miss an OS anymore.
Finally we build a 2-layer PCB with an STM32F4 which we've ordered at Hackvana. We solder the PCB's manually like it's done at the reflow procedure. Well... we use a crepes plate to solder the PCB's
No late April fool! => https://drive.google.com/file/d/0BwzVll ... sp=sharingWe firstly tried to use the STM32 UFBGA176+25 package and it worked already fine for 3 PCB's. We've soldered other BGA's before but not such a big one.
Last week, we got our first PCB into the air. The final payload had a weight of 30g. It's main features were:
- Live Imaging (transmitted by APRS and SSDV)
- Live Position (GPS position transmitted by APRS and 2FSK)
- Solar enabled (we flew a 2Wh LiPO)
- Telemetry transmission (Airpressure, Temperature, Humidity)
- Power consumption and solar charging tracking
Thomas wrote a short article about it. We got some useful pictures on the first day around Germany, Austria and Italy. Basically it worked very well. We got a lot of useful images transmitted. There can be still done some improvements (especially on the camera). We experienced some bad DMA/DCMI errors in the air which were caused by the low temperature most likely.
Short article with some payload pictures
All transmitted pictures from the balloon
Balloon Track
For everyone who's interested about source files (everything is open source):
Hardware: https://github.com/DL7AD/pecanpico7 (branch 7b: new revision, branch 7a: the PCB which we've flown), the project can be opened and edited with the free licensed Eagle version
Software: https://github.com/DL7AD/pecan-stm32f429
My DCMI ChibiOS evaluation code for the OV9655 camera: https://github.com/DL7AD/STM32F429-DCMI (Applicable on all STM32F4 eval boards)
Regards and many thanks to Giovanni for helping
Sven DL7AD/AF5LI
There haven't been any valuable photos due to the packet loss. We experienced the same problem on a flight which is still ongoing => Track: 
Sorry for my delay. I think, you might be right. I took the code from a friend who also does ballooning.