Re: PCB version control

On 3/25/2025 6:53 AM, Don Y wrote:

On 3/25/2025 3:44 AM, Don Y wrote:

   "No.  I can replace a single page if necessary.  So, each EPROM
   /in the set/ can be at a different revision level.  It's up to
   Engineering to manage this (configuration management) so only
   valid "combinations" of those devices are incorporated into a
   released product."

 This last is important.  If you want to force a production change,
you have to change a part number, not a revision level.
 E.g., I can revise an algorithm in a particular piece of code.
Any revision will perform identically (if performance is
defined by getting the correct "result"/return value).  A new
revision may change some other aspect -- a faster algorithm,
smaller, better documented, etc. -- but is same fit/form/function
as the earlier revision.
 If I *need* the product to use a newer version of that algorithm,
then I have to give the function a new part number and update the
BoM (makefile) to reflect that new part number.
    for x in 1,2,3,4,5
   do
      <blah>
   done
 can be replaced by:
    for x in 2,4,1,3,5
   do
      <blah>
   done
 if side effects are ignored.  So, there's no need to discard
the builds where the first version was embedded in the binary
in favor of the second.
 However, if the second MUST be used, then it must carry a
different P/N so the referencing BoM calls out *THAT* P/N.
 But, most folks don't treat software as "trackable components"
and assume the revision is part of the part number.
 

OK so...how should I do revisions of this PCB/product (the product is the PCB) again? It has a board, and uP code, and FPGA code. Can you provide a motivational example
Apparently HP had it right when every product was just like some meaningless number followed by a revision letter, eh?