"PICAXE is not recommended in safety critical systems.".... I have seen this warning posted many times for Picaxe. I understand it, but I am wondering a couple of things. What microcontroller would you recommend for safety critical systems? Why don't Arduino, Basic Stamp, BasicMicro, Athena, Dios, and other bootstrapped, entry-level microcontroller systems emphasize this more?
I have worked tens of years with industrial electronics, and with that background, I answer your question: NONE!!!
If REALLY someone is in danger, if a uP "tilts", it should not be used at all, OR THE SAFETY SHOULD BE ENSURED BY SOME OTHER WAY.
That kind of statements are a legal thing: manufacturer/reseller HAS TO WARN, that there is a POSSIBILITY of malfunction, wich CAN CAUSE danger and sever injury.
Understand, what I mean...
If a microprocessor is used in home a/v-system, and it goes haywire, the only danger is ,that you pop a vain in your head, when you get angry...
No other danger to physical injury.
If a microprocessor is used ,for example, in a car, in some critical system (engine, breaks,safety-equipment etc.), the failure can cause IMMINENT DEATH or injury.
In avionics, EVERY system is AT LEAST triple, when uP's used.
I DO NOT mean to be negative. Just tried to explain.
IF You use a microprosessor, THINK, what an error COULD CAUSE.
If ANY possible error CAN NOT cause any real danger to anyONE or anyTHING, use it with good consience.
If You find a POSSIBLE danger, use the device anyway,but NOT BEFORE YOU HAVE INVENTED, HOW TO PROHIBIT THE BAD CONSEQUENCES IN SOME OTHER WAY.
Many times, the "other way" means something very different, even a mechanical way. For example, if a machine could cause injury to people,when microprocessor malfunctions, build a fence round the machine!
The most important thing in making devices/programs in the "real" environment , is to think error-consequences and to prevent them!
Remember! Only Governments and Corporations can do "damage control" , not people or small companies!
The latter has to think things in advance...
Edit:some typo's corrected