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Could also have a single flight termination string that blows everything in a specific order determined by the flight computer and use separate commands for ground testing that incorporate sending a bit mask of which channels to blow. Something like [deployment test string | one byte mask ]. The one byte mask could support 8 distinct channels.
It may be best to let the flight computer decide how and when it wants to blow charges. It may check continuity, blow charges based on altitude, blow everything at once, delay blowing charge caps on the same side, etc.
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