This is a 10DOF daughter-board for Adafruits Feather boards.
* 3-axis accelerometer
* 3-axis gyroscope
* 3-axis magnetometer
* temperature sensor
* pressure sensor
* humidity sensor
* 8 servo headers (PWR from BAT)
* SPI header
* UART header
* one green and one red LED
* one switch
* GPIO#9 (A7) is connected to BAT to measure it's voltage
The board has been produced and tested.
* all sensors work
* red LED works
* green LED is on when connected to USB, but not battery - no idea why
A couple of days ago the boards arrived. I had them made at dirtypcbs and I'm pretty happy with them. It's the first time I actually spend time on cleaning up the silkscreen. Unfortunately, some of the silkscreen wasn't printed - probably because it was to small or in the wrong place. The SPI header should have pin names next to the through-holes.
This is about the fifth board or so I ever SMD soldered. I almost did everything right - except that I used tape to fix the board on the desk - and with that tape I covered the landing pads of the 10k resistor for the switch. So after I applied solder paste with the stencil, I had a perfect spread, except for that resistor. You can see that I hand-soldered it on later with the soldering iron. The rest of the parts I could place and then solder with a heatgun.
After building comes testing and it seems to work pretty good. The sensors work, LEDs work.
However, the green LED does something shady. When the motherboard is connected via USB, it goes on, but as soon as the battery is connected, it goes out again. I have no idea why.
Anyway, next step is to solder one servo header on and put this in my water rocket. The parachute deployment system is already done and tested with remote control, now it's time to automate. I already have flight data from earlier prototypes. The parachute should be triggered on the highest point of the flight. The barometric data isn't really good enough to do that, but the acceleration is. Basically, as soon as the thrust cut's out, the rocket is in free fall and therefore zero-g - except for the aerodynamic drag. This drag is a small negative acceleration that gets smaller the slower the rocket gets - until it's zero when the rocket is at the apogee with zero velocity. Due to noise I can't set the threshold to zero, so what I will do is to detect if the acceleration is below 0.1g and then trigger the parachute with a slight delay.
I added another header that exposes SPI and two more pins, so it's easy to add a wireless module - or anything else SPI. It's basically some holes in the PCB where I had space left. Easiest way to add wireless is to just a Feather board that already has it.