First attempt at PCB design

Hello Rob,

Your .pdf of the schematic hasn't worked very well, it's been chopped up into multiple pages. If you could set up your PCB CAD system to convert it to a single page .pdf it would be possible to look at it without printing and sticking bits together.

MK

Ah, my apologies, looks like my printing settings didn't get carried over. I've updated the link now.

// Robb

Ah, my apologies, looks like my printing settings didn't get carried over. I've updated the link now.

// Robb

Hello, Would like to make some 'hobbyist level' PCBs and haven't made any for many years now. Since the day's that I was an electronics hobbyist (really want to get back into the subject though) Is there anyone on here that can make any recommendations on PCB layout software that is either reasonably inexpensive to buy failing that (and better still) downloadable under an Open Source license please?

Also are there any PCB manufacturer's that are willing to help hobbyists with their PCB needs as opposed to having to go to large scale manufacturer's of whom probably won't sell to end users only to volume buyers?

Are you making some form of weather station Robb? Sounds interesting anyway.

Hope I've not asked the above questions in the wrong thread. Should a new thread really need posting I've no problems with an administrator moving this post as necessary. Thank you.

I'm using Eagle free edition for this layout, I've found it relatively easy to use. The project is to battery power these and deploy them into a building to measure various environmental variables then collate and analyse the data.

// Robb

Hi Robb,

Thank you for the recommendation - Much appreciated (is this easy to use for newcomers?)

The project sounds fascinating. I'd love to build a RaspberryPi based weather station and understand that CPC are considering obtaining the PCBs for the AirPi weather station shield (possibly the full kit too but am not 100% certain about this).

Best Regards.

As I said, this is my first attempt at designing a PCB, I've found it relatively intuitive to use, there a few quirks that I quickly found out by studying existing schematics and board designs. but I found it quite easy to cobble this together from the existing schematics for the dev boards that I used in prototyping it.

// Robb

Your schematic isn't very easy to follow - I would usually try hard to avoid the "pin list" format where there are few wires and you have to go hunting for names all over the sheet. I usually break the processor up into several blocks where I've arranged the pins for convenient drawing. It means I don't use library parts and I end up with a new processor component for every new project - but I think that's a small price to pay for the readability that goes with it.

You could try adding more notes to the schematic - I don't know what half the circuit blocks are trying to do so I can't comment except in the most general terms.

I can't see any pull up resistors on the I2C bus  - these are essential and I doubt (but haven't checked) that the process has them built in. There is no standard value for these, you can read the NXP (its their bus) i2C spec and work them out or start with 2k2 and see if it works.

I also notice that you have GND and AGND - where are they connected and why are there two of them.

Finally, well done for using the Cozir CO2 sensor (a fine part made in Cumbernauld near Glasgow by GSS) - I was involved in the design of the electronics and software inside it

MK

Hi, Can you make any recommendations where a PCB manufacturer is concerned please?

Thank you.

Hi,

I use Design Spark and it is easy and intuitive and can easily do double sided. The printing onto acetate sheets for use in a UV cabinet are easy.

I also use DesignSpark PCB due to its lack of size limitations and it is free for commercial use.

For board manufacture I tend to use PCB Pool and found them helpful with their board checks which is good for beginners. Like many manufacturers they also have useful documents and FAQ's. Although one off prices might be higher than other cheap imports their quality is excellent and the price disappears in the overall design cost

As for what PCB software you use, check the restrictions as well as the features you require, make your choice and then learn it. Most do a pretty good job once you learn the ropes, but don't fall into the trap of using lots of different free packages and never learning to drive them!

@Robb Gosset, some general advice:-

Check the PCB footprints against the manufacturers data, don't take anything for granted.

Don't rely on autorouters for the 'best' layout, pcb artwork is part of the designers process, layout for performance not for neat regular arrays of components.

If hand assembling use the larger pad options for SMD's and allow space for soldering.

I don't like side entry tracks or under component tracks connected to pads, think of testing and modifications.

Don't go for the smallest of everything, try to go as big as your available space allows.

Use 'standard' tracks, pads, vias etc. and check with the PCB manufacturers website what they allow as standard prices and don't accidentally go for premium options.

For prototypes I sometimes use vias without solder resist (when not under components) such that they can be test points and also allow easier mods such as track breaks and wire links.

There's lots more to learn, but that hopefully gives some pointers.