I designed my final circuit, and I need to build multiple units of it. Essentially, I require 20 to 25 units of it.
I would prefer to avoid constructing all of them using stripboards and instead create something more stable.
That's why I plan to design a corresponding PCB and send it to a service to have multiple units printed.
The circuit I designed is relatively simple (I'm not an expert, but it seems to work fine using the breakout board). The design includes:
Unfortunately, this is my first time designing a PCB, and I don't have much time to dedicate to studying (and perhaps I lack the necessary skills as well).
I have started using tools like Kicad and watching tutorial videos, but I would like to seek help from an expert.
Is there anyone interested to create it (I am willing to pay if needed), or perhaps someone who could guide me through the process?
One thing: drop those RS485 modules, these are designed for point to point communication and not a bus system. They have the 120 ohm terminating and biasing resistors onboard, these should only be installed on the first and last unit in the bus.
Include the RS485 chip on the PCB, much cheaper.
Thank you for answering.
Before providing you with any additional information you may need, I have a question about the point you highlighted.
I require the RS485 module I mentioned to create a master-slaves network.
Sorry, I'm not an expert... what do you mean by "these are designed for point to point communication and not a bus system"?
Is it not possible to use this module for this purpose?
What alternative are you suggesting? Can you provide me with an example?
@safari83 Please do some research. RS485 is a multidrop network, with certain electrical characteristics. One of those is termination resistors at bus ends, but not at every device in between. Those modules have the resistor onboard, so cannot be used indiscriminately. I remove them from my modules, because I want to use the modules for easy swapout, but @ldt006 is correct, it's much simpler to put the circuit on your PCB, socketing the MAX485 itself if needed.
That doc may be confusing, but you should be able to glean what you need.
I'm not "qualified" to do the job, but a couple of things to be aware of...
I've worked in electronics a long time and I don't think I've ever seen a board come-out perfect the 1st time. Sometimes it can be made to work with "cuts & jumps" and sometimes it has to be scrapped. I've got a board in front of me now and it says "Rev 3". The prototype board would have been Rev X0 and there might have been a 2nd X1 prototype before the 1st production release at Rev 1. So this is at-least the 4th version! (I think a "feature" or two were added so it's probably not really the 1st working board.)
Of course it's all negotiable but typically freelance PCB designers work by the hour and you can expect to pay at least as much as a plumber. The contract is usually "best effort" so the work is not guaranteed. (They might re-do their work if they make a mistake but it's unlikely that they will pay for scrapped boards.) And you may have a schematic error or other design error, or an error in the information-documentation you supply him/her and of course that's your responsibility.
I've recently designed two boards (Arduino related hobby projects). Both are pretty simple but it took 2 tries to get the 1st board right. I'm playing around with the 2nd project now and I had to make a couple of "repairs". It looks like I can make it work, but once I'm sure I've identified all of the issues I'm going to fix the design and order new boards. I'll probably want 5 or 6. If it was just one, I'd probably "live with" what I've got.
Both times I really-really tried to get the boards perfect the 1st time so I was disappointed but from what I've seen in the industry I wasn't THAT surprised and I was mentally prepared for the extra delay and expense of a 2nd version.
I started with KiCad but I got frustrated trying to make a custom part by simply modifying an existing part. I switched to DesignSpark and that's what I ended-up using. But it WAS many hours of learning and struggling through something new.
P.S.
One company I was working for did a rush-job and they paid extra to have the boards fabricated in 2-days and they paid the assembly house for 1-day turn-around. It was a simple board but they sent the boards to the assembly house without checking or inspecting them.... Not enough time for checking... The board was missing the entire data bus so they had to be scrapped and of course they were late for whatever they were working on...
Design iteration = time. Increase design iteration, reduce revision count; there's no free lunch. Doug's experience holds true. Yes, someone might get it right first time, if they've either done this for a living, or got horsehoes up..., but in reality you'll most likely end up with either multiple board mods on all 25, or a board with R2 or R3 in prominent display.
I just read the original topic and agree with some of the posts but disagree with others: That's life .... and experience?
An Every is way overkill for a simple project like this, I really don't see the need for 2 hardware serial ports, the OP (being a software engineer) should know if he needs this for his design
A Nano is more than enough for this and for 20+ unit's: Why not use the 328 chip on the PCB and program it with ICSP or a USB programmer. Much simpler and reliable.
There is no need to have 20+ USB chips sitting there consuming power, only needed once for uploading the sketch.
Just my 2 cents......
Yup, design tradeoff. Happens all the time. Simple 2 sided dead easy IO layout, add socket and drop in the Every, or even solder it in, or add in the complexity of duplicating the design work done on the Every layout just to 'simplify' the end result.
YMMV, it's always that way.
Well @safari83, even having a paid consultant do it for you may not be as easy as you thought.
Sometimes it just plain easier to do it yourself.
You might consider using EASYEDA, it's simpler to learn than KiCAD
if I understand correctly, the RS485 module that I linked here has the resistor terminator integrated on the board... shit!
Can you show me this resistor in the image please? In case, can I remove it from the board (just to test it)?
Are there similar modules without this integrated resistor?
Since your link goes to an italian Amazon page, I can't see the image. Post just the image of the product, top view if possible, and I may be able to point at the resistor.
Should, by the way, be an SMD resistor, probably with 121 printed on it, but I can't confirm unless I see an appropriate image.
@jim-p with only 8 in circuit right now, I've not had to(scope signals show good form), but you are correct, they ultimately become excessive when too many are in parallel. What I'm less sure of is how many would constitute 'best', and where to locate, it's less clear to me than for termination end-to-end. It's certainly one of the compromises to be considered with RS485, it's not just pick-and-place, as is clear in the design doc I linked to.
Of course, the original design itself was limited to 32 points; the 1/4 load concept allowing a full 128 devices came along much later.
