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From: john larkin <jl@glen--canyon.com>
Newsgroups: sci.electronics.design
Subject: Re: PCB version control
Date: Mon, 24 Mar 2025 14:47:53 -0700
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On Mon, 24 Mar 2025 13:16:53 -0700, john larkin <jl@glen--canyon.com>
wrote:

>On Mon, 24 Mar 2025 14:51:11 -0400, bitrex <user@example.net> wrote:
>
>>On 3/24/2025 2:46 PM, john larkin wrote:
>>> On Mon, 24 Mar 2025 14:14:38 -0400, bitrex <user@example.net> wrote:
>>> 
>>>> How do you version control your PCBs these days?
>>>>
>>>> I'm at the point I need to implement a more consistent schema for
>>>> hardware versions, prototype, and production boards.
>>>>
>>>> E.g. PCB-12345-R-B where 12345 is the PCB/product identifier and B is
>>>> the manufacturing revision. Would you letter designate prototypes that
>>>> are manufactured as well, or just revisions intended for public
>>>> consumption?
>>>>
>>> 
>>> For a V375 VME module, our schematic drawing number is 22S375A, where
>>> 22 means the VME product line and S means schematic and A is the rev
>>> letter.
>>> 
>>> 22D375A is the PCB fab (drill) drawing and pcb design file name.
>>> 
>>> 22A375A is the pcb assembly drawing.
>>> 
>>> 22M37501B might be a mechanical part drawing, like a front panel.
>>> 
>>> 22A375.1A is the BOM file for the sellable -1 version.
>>> 
>>> During development, we iterate the schematic and PCB together, as
>>> 22S375A4 and 22D375A4, for example.
>>> 
>>> We have a formal procedure about all this. FPGAs, uP code, test sets
>>> and procedures and software have to be coordinated too.
>>> 
>>> Times hundreds of products with rev letters and dash number versions,
>>> this gets serious.
>>> 
>>> Prototypes are 99 series, with informal project files on a server.
>>> These are essentially little breadboards. We don't prototype entire
>>> products; we just release the full rev A document set to manufacturing
>>> and expect it to work.
>>> 
>>
>>
>>I see, that makes sense. Some designs I'm working on now are modest 
>>enough that can do that with the entire product relatively cheaply, so I 
>>guess, y'know, existentially speaking, if "A" ended up needing major 
>>revisions, but _if_ it had worked first time it could've been sell-able, 
>>that should count that as a letter-revision.
>>
>>That is to say I guess it makes sense to be consistent and give any full 
>>board that gets manufactured in whatever quantity a letter revision, and 
>>I like the idea of giving "little breadboards" that aren't a full thing 
>>their own project/test series designation
>
>We roll the rev letter if there is any change to the schematic or the
>PCB. Dash numbers identify versions, like parts values or stuffing
>options. A new BOM can create a dash number without revving the PCB.
>
>This is a quasi-military drawing number system which is in fact
>acceptable to the US military and NASA.
>
>It's important to note that only physical things have dash numbers.
>Drawings don't.
>
>We have one big customer that assigns the next available 12-digit
>number (their 12NC) to the next thing that needs a number. A
>schematic, a forklift, a building, an employee. You need a
>cross-reference to tell which schematic corresponds to which PCB. 


The airplane boys used a drawing number and a rev letter and a dash
number to define a part, like an airplane wing. The convention was
that xxxxx-1 was a physical part defined by drawing xxxxx, and xxxxx-2
was its mirror image. -1 was the left wing, I think.

We don't do that, but we assume that drawing 22A123A defines part
22A123A-1, but the drawing can say "pink anodize -2" or some such.

Military and aerospace folks usually require that any physical part
have the full part number (with rev letter and dash number) engraved
on the part itself.