Content originally posted in LPCWare by EtaPhi on Thu Aug 21 05:41:41 MST 2014
starblue, LabRat, your replies are very helpful for me that I'm discovering LPC micros.
My initial development is going to use a LPCXpresso LPC1549 board, while the first prototype board is being built, so USB isn't a real issue.
It's however an issue for the final application, which is airborne.
Since it's a scientific mission, there is no need to comply with DO-179 regulations, but it's better to agree with their mindset, which may be summoned as: "what doesn't exist, can't broke!".
USB support adds weight and pcb space due to connector, ESD protection devices, etc.
It's almost useless for my application.
If there exists a part without USB (as it exists), I prefer it, because I don't have to provide evidence that a bug my activate that unused feature.
Even if LPC15xx micros are COTS (commercial off-the-shelf) components, a triple redundant system, i.e. three LPC15xx working in parallel, with an appropriate voting logic should be DO-179 compliant (if submitted to a third-party certifying authority).
Airborne devices may experience unexpected resets, which may be due to ionizing particles, EMI etc.
It's therefore better to recover from such events as quick as possible, but ISP bootloader must not interfere with reboots.
This is the reason of my request, which addresses a documentation void.
Regards
EtaPhi
