This small flight computer is the same computer as my MINI FLIGHT COMPUTER (BREO N) but it has a front panel that allows for it to be mounted not only inside the rocket but also on its fuselage. In some cases this might come handy where payload section of the rocket can be assembled home instead on the field. Also it can permit a simplified construction for multiple usage of the flight computer i.e. it can stay permanently mounted.
The rest is identical with BREO-N – they share the same firmware and software and the schematic remains unchanged.
This flight computer can be installed entirely inside the rocket as any other flight computer. Also it can be installed on the fuselage from inside or outside as shown in the pictures below.
The total high of the board is 1.5mm less than the front panel so that the front panel can completely cover the cutout. When installing it from the outside, the rectangle cutout can be made little narrower than the height of the board and it can be inserted like this:
The firmware which has basically three main parts – USB part, on-the-field maximum altitude calculation and the flight mode is the same as for BREO M.
And regarding the PC software, the both devises share the same program.
RocKI (http://kia-soft.narod.ru) mentioned a situation where a false start condition could trigger the flight computer. As a result the computer could be fooled and the ejection charge could be fired untimely. This situation arises when the electronic bay is tidily closed and the next bay is mounted on the top by pressing it down. This acts much like a piston and temporarily increases the pressure in the electronics bay. As soon as the pressure starts falling down to equalize with the surrounding pressure and if this is combined with a strong shaking of the rocket, then the start detecting algorithm will be fooled that the rocket is launched.
To avoid this problem I made some modifications in the firmware start detection algorithm – now it is much harder to have a faulty start triggering. However as a result of the new algorithm you should allow about 30 seconds between switching on the flight computer and launching the rocket. This time is necessary for the flight computer to make some additional calculations. Launching before those 30 seconds have elapsed could result in faulty initial calculations and this could have detrimental consequences.