This project was mentioned in this month’s Sport Rocketry magazine, so I thought it would be a good time to post a status update on the project.
(If this is your first visit here, have a look here for background as to what the project is about.)
This spring I finished my “Rev4” circuit board, with the PIC32 CPU:
This board also has a USB interface and a Microchip MiWi (ZigBee/IEEE 802.15.4) radio module on board. The “Rev4A” board pictured here is using the GlobalTop FGPMMOPA6 GPS module (the big square thing on the right), which reports at 200 mS intervals. I’ve bought a few of the new PA6B modules (100 mS), but haven’t tried them yet.
The only problem I discovered with the Rev4a hardware was my circuit for driving the piezo buzzer – what I’d meant as an amplifier to make it louder instead shorted it. Happily I’d left enough test jumpers that bypassing the amplifier circuit was nothing more than leaving out 2 berg jumpers and adding a single wire between the pins. So it works and makes noise, but isn’t as loud as I’d like.
I’ve since designed and had fabricated (BatchPCB again) a “Rev4b” PCB that fixes this problem and is about 30% smaller, but I haven’t yet had time to populate and test it.
I started by porting over all my old 8-bit (PIC18) code to the PIC32, making improvements along the way. So far I haven’t written any code to drive the radio or the USB port – the hardware is all there, but it doesn’t do anything yet.
I test-flew this board twice on April 24 at the CMASS launch in Amesbury MA. Neither flight was perfect (see Flight Test Notes for flights # 26 and 27) but both were sucessful enough to build some confidence in the stability of the Rev4 hardware and software.
The next project was to either get the telemetry radio and USB working, or to port the navigation code (that will steer the rocket back to the launch site using GPS information) onto the Rev4 hardware.
I tend to like to do things slowly and carefully, one step at a time (perfectionism), so my inclination was to get all the Rev4 hardware working before I started on the final goal of navigation. But the famous words of Michael Faraday when young William Crookes asked him the secret of his scientific success came to mind:
The secret is comprised in three words — Work, finish, publish.
It had been 4 full years since I’d started this project, and I still wasn’t navigating back to the launch site. While it’s true that this is only a hobby project, and I’d been busy in the same period starting a business, raising a family, etc., nonetheless I decided it was time to focus on finishing first, and polishing later.
I’ll bring things up-to-date on that in my next posting. For now I’ll leave you with a video of my most recent flight, from yesterday, July 17: