I ran into an issue in that I was running out of RAM for my Arduino program. Someone told me about this chipkit boards that were arduino compatible and had 8x as much RAM, so I sprung for one. Then I found that two of the libraries I was using for my program were not compatible with the new chipkit. One of the libraries inverted the signal from the Garmin GPS 18x LVC unit I was using. To invert it now, I would need to put a MAX232 chip on a Printed Circuit Board (PCB). I figured, while I'm making a PCB, I might as well use the old Inventek GPS I got back in November. Bill French (from FUBAR labs) and I made the PCB and got the GPS working using the toner transfer method in just 3 hours after I finalized the design. In the picture above you see the board.
Shortly afterwards, I finally managed to get the NTX2 transmitter properly hooked up to both Arduino and the chipkit board. Very ironically, I then discovered that the other incompatible library was SD.h, which is what I was using to write to the SD card (to store data onboard in case radio transmission failed). It's ironic because I wanted a board with more RAM so that I could increase the size of the buffer I was using to write to the SD card :-/
The good news is that the company that makes the chipkit boards supposedly has someone working on making the library compatible, and I was told this morning that changes are going to be uploaded soon. Hopefully those fix the issue.
This is where it starts to get exciting
So now comes the time to scramble to get everything done. Tomorrow, Saturday, is really the only time to launch, since Sunday CENJARS (Central NJ Amateur Rocket Society) is having their monthly launch, which I am planning to attend with a recently-bought-and-not-yet-assembled Norad Pro Maxx. We still need to build/obtain a yagi antenna for the receiver, any sort of antenna for the transmitter, a radar reflector, and build up the housing. We set up a power test of the radio last night, hopefully nothing fucked up and we'll have some results by the time we get back to the lab today.
But other than all that, we also need to drop test the housing with the parachute to figure out the descent speed and plug that into the predictor. And we should do some sort of range test on the radio, since that last one we did lasted about a block. I'll feel a lot more comfortable if we can test the thing with the proper antennas and at least get to the point where we can't just yell at each other to see if it's working.
I also need to buy some wire that will attach the parachute to the balloon, build the cutdown mechanism, and I still haven't bought the helium.
The helium gas is going to cost $80 for 200 ft^3, and $10 for a tank rental, with a $100 deposit. There's all this stuff left to do, but the helium must be purchased by 4:30pm today, or else the place closes and we're SOL, unless we can find a helium supplier that's open on the weekend. They tell me they'll give me a full refund for the helium as long as the white cover remains on, which is comforting, but there's still so much making me nervous about the project with everything coming together so quickly.
Oh well, it's "don't talk about it, be about it" time. It's something my friends and I say when it's to stop talking and get down to business. I'll post some more photos tonight of the flight computer that I soldered to the protoshield yesterday, and other equipment we end up building. After that though, we'll just have to launch, track, and hope everything goes well.