Is it normal for a designer to have internal BOM preferrences? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: February 13, 2020, 06:26:23 pm
content: For example, when I want to have a simple USB microcontroller with UART, SPI and a few GPIOs, I have a strong tendency to choose STM32F042F6P6 + 8MHz ceramic resonator over other choices. Is this normal?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 13, 2020, 06:49:45 pm
content: I mean, nobody's familiar with everything... what's worked before is likely to work again.Tim

author: james_s
author_rank: Super Contributor
timestamp: February 13, 2020, 06:53:32 pm
content: I certainly tend to stick to parts I've used before and know will work well unless I have good reason to investigate something else. If it ain't broke, don't fix it.Do keep an eye out for better solutions that may come along but unless it brings significant advantages there's nothing wrong with sticking to what you know.

author: m98
author_rank: Frequent Contributor
timestamp: February 13, 2020, 06:59:24 pm
content: Sure, most designers have some favourite parts they're familiar with. If they do the job well enough, there's no reason to choose something else.I have a selection of tested circuits and layouts to just C&P into a new project. It would be quite inefficient to solve similar problems differently every time.

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 13, 2020, 07:20:09 pm
content: I dunno what "normal" should be, but common, certainly. It's akin to what I said here:https://www.eevblog.com/forum/projects/why-audiophools-love-lt10838485/msg2917066/#msg2917066Yes we all (more or less, and often depends on the category of part in question for each of us) tend to do that.And when it comes to MCUs, the benefit of reusing a part that you have used before, that did the trick and that you know well are obvious. You don't need to read a brand new datasheet to know how to integrate it properly hardware-wise, and you don't need to install/learn new development tools, register lists and libraries, and can reuse a lot of code you already wrote.The benefits for simpler parts are often less obvious.Oh and interestingly, the relationship engineers have with saving time is a complex one, and largely depends on your work conditions.Some like to save time because that's just part of our natural laziness (which can be a good thing here!), others don't because that's less opportunity to learn new things.Likewise, some like to save time because they know how time is valuable (either because they just deeply know it, or because they run their own business!), others absolutely don't care about saving time, especially when they are just employed and are paid not by the tasks they achieve but just by passing time.

author: i_am_fubar
author_rank: Regular Contributor
timestamp: February 13, 2020, 09:13:10 pm
content: An engineers toolbox of design patterns is their most valuable knowledge. It allows them to be quick at decidiong at least one solution before even having to conisder another. a few of mine:Motor control PWM & Quad encoder -> PIC18F2431 w/internal clockCabled low speed comms over distance -> RS485USB design -> FTDI if it's just data.LED on 12v or less? 1kseries resistorThey may not be the most efficient, but I can crank them out as quickly as I need to prove something.The danger comes as you get older and technology moves on, and the youngun's come into the office with swanky new ways of doing things, and suddenly your design patterns become old news.Do your best to learn. Be prepared to accept change. Be open to the new ideas. But always question them with integrity.

author: sam[PS]
author_rank: Contributor
timestamp: February 28, 2020, 04:41:12 am
content: 100% normal and actually strongly advised for professional. I'll explain this in one term : NRE (non recurring engineering).In your case you spent probably 10s or 100's of work hours getting to know that part, it's strength, it's limitations and some workaround for these. Not to mention you probably have build yourself a library of functions for most features (if not you probably should have) or at least you have some code base to cut/past from.Using another MCU can mean to throw most of that already made/paid work to the bin. The little feature that that other MCU might have a bit better should be really hugely important to justify this cost. Remember that in most electronic product the biggest cost factor is our time as EE designer. Spending weeks on just restarting a new basic function library to cut few cents on BOM cost is most likely a bad idea.There is always more than one way to skin a cat, but just the time spent trying to think about witch one might be better would probably cost you more than any benefice that could be made out of the better/smarter choice.It can also be a logistic/organisational concern. Some company have a centralized component database and EE designer have to pick their component from there. Using a part that is not in this database then require a special exception procedure. That allow for more fluid operational process (eg you are sure that the pcb layout team will have the correct footprint if you pick the part from the database) and quicker turnaround (you can stock parts locally and thus avoiding some global market availability alea)Now if you are a student or an amateur wanting to learn as much as possible then it's the opposite, try to confront as much cases as possible, that's how you'll build up a general culture.Just my 2cts...