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are drawing normal schematics a dying art?
VK3DRB:
--- Quote from: Berni on November 16, 2021, 03:12:14 pm ---
--- Quote from: VK3DRB on November 16, 2021, 12:13:53 pm ---Altium allows you to you harnesses in schematics. Harnesses are OK if used wisely and the engineer does not go over-board ('scuse the pun). I have seen harnesses grouping harnesses grouping harnesses! And with harnesses' signal names changing between sheets. The engineer who created it made such a mess, there were Altium harness errors he left in the design, then he left the company. I ended up fixing the errors, and in doing so I found two instances where where one digital output was driving two GPIO digital inputs in a processor.
I do use harnesses myself but rarely. Altium made a mess of harnesses in my opinion. Changes to harness names is not trivial.
I think that engineer is like some sharp coders who make a point of writing pointers to arrays of pointers which point to pointers so that the appointed engineer points out he doesn't see the point.
--- End quote ---
Yeah i am not a fan of how harnesses work in Altium. They are a great idea, but poorly executed....
...That being said i still found this style of schematic used in confusing ways where parts of a circuit are cut up in a nonsense way and spread across two or more modules, so you have to constantly flip pages to figure out what is going on.
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Exactly. Great idea but poorly executed. Problem is when Altium creates something down the wrong path, they cannot easily fix it because it breaks earlier schematics. Backwards compatibility can sometimes be a curse.
I had an ex-colleague who worked for a company in Canada where they have one page per IC and even one page per transistor. He told me they had perfected stupidity to a fine art. As you say, a good schematic minimises page flipping and maximises comprehension. Page flipping slows down the productivity of debug technicians in Production. Years ago some TV schematics had oscilloscope waveforms in various circuits to aid fault diagnosis... they were brilliant because they considered the plight of the user (TV tech). In fact, TV sets often came with the schematics tucked away inside the set.
Net labels with sensible labelling should proliferate in my opinion because they aid track layout work so we know exactly what each track is for to minimise crosstalk, consider currents etc, without having to refer to back the schematic all the time. Some net labels can be very small if they are benign to the end user, eg: "TP23".
james_s:
One page per transistor? Unless the circuit contains a very unusual ratio of transistors to passives that sounds extremely tedious.
Berni:
--- Quote from: james_s on November 17, 2021, 06:53:40 pm ---One page per transistor? Unless the circuit contains a very unusual ratio of transistors to passives that sounds extremely tedious.
--- End quote ---
In guessing the people there got so used to working with ICs and not much with discrete analog anymore. So perhaps a transistor is simply there for making a open collector output or a switch. So its 1 transistor doing 1 job.
I do sometimes do a single chip on a page. This is mostly on things like MCUs and FPGAs where that page caries the massive chip symbol/s and out of that schematic i have ports with sensible signal names. That way the top level schematic just show a "VIN_SENSE" going into the MCU block, but if you want to know exactly what pin that goes to you can just open it and see what pin it hooks into. This information usually quickly gets turned into a .h C header file, so its no longer needed afterwards.
The one annoying thing to clearly show are UART lines. There is no strictly defined master/slave since both nodes are symmetrical while you do have to cross over the RX and TX lines for it to work. So naming the nets becomes tricky. This is where the Altium direction arrows on the schematic sheet ports help, but sometimes i have UART going into a connector. I started drawing extra direction arrows there too in order to show what way the data is flowing.
RJSV:
A slightly off-topic, is the old phenomena: The Drafting Dept. And the folks doing that work, 40 hpw.
My approach, in a small business, used the schematic and other supposedly in-house packaging documents, in marketing. So, a sub-system package might include cables (schematic), plus lots of views of enclosures. That makes for a market-ready document and as a bonus, helps keep marketing dept. realistic in promises made (i.e. to the customer).
The old-school: DRAFTSMAN that's what I got started thinking, and that (was) quite a role, back in da day.
Zero999:
--- Quote from: Berni on November 18, 2021, 07:41:29 am ---
--- Quote from: james_s on November 17, 2021, 06:53:40 pm ---One page per transistor? Unless the circuit contains a very unusual ratio of transistors to passives that sounds extremely tedious.
--- End quote ---
In guessing the people there got so used to working with ICs and not much with discrete analog anymore. So perhaps a transistor is simply there for making a open collector output or a switch. So its 1 transistor doing 1 job.
--- End quote ---
When transistors were expensive, some designs did have a lot of passive components per transistor.
A single transistor LED flasher I designed just for fun. Yes I know it's possible to use a transistor in reverse bias mode, but it doesn't work at low voltages.
phaseshift LED flash.asc
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