Re: HAL analogies and reliability

[RICH RUDMAN <rmanzan@TSCNET.com>]

Eric Chang wrote:
> 
> >Dave, I can see through your side-view mirror camera, that your >moving the
> >floor jack this way.
> >Dave, you really should stop.
> 
>> 
> Many engineers (software, mainly) roll their eyes when asked to put
> in a hardware override. .  Be
> careful out there.

Us Power guys just love it when a brainy PHD type PooHoos a hardware Gate drive buffer. "The CPU will never fail"..It's not the CPU that we 
are worried about. It's the fool who writes the software. Software screw ups are the norm when debuging and developing code.
	I have a pile of chicken resistors and small loads that get put in line when first fireing up new hardware. It may be weeks of code 
and hardware design before the saftey comes out of the loop. Then we take a first flight to full power, with one hand on the throttle and on 
in the breaker.
	I don't know how many times the Vesats have locked off, with a polite Chunk!, when my software tried to turn on all 6 Gates of a 3 
phase inverter... This is a really good Homer.  I have versions of buffered drives that take a completley inverted drive logic. Resetting 
turns them all on... instead of off. 

Without safteies and practical design backup and fail mode traps... power hardware can not be designed, or tested.

Oh yea the Minibike from Hell will climb and accelerated up my %20 sloped drive way. NO fried power stage yet.

Progress is being made... on many fronts. 

Rich Rudman
Manzanita Micro