Request for help checking first project?


#1

I would be grateful for any assistance looking over my first kicad project… I think I am done, but I’m sure more experienced folk will find I’m not :smile:

I have a series of 8 screenshots showing the PCB layout, the schematic, and the 3D view. I’ll post just one here and now because I am not sure whether posting 8 would be ‘rude’.

Overall the project is a ‘cape’ board for the Beaglebone Black, which is in turn based on the Sitara ARM MCU. The project adds an Analog Devices 8-channel 16 bit simultaneous A-D converter, the AD7761, buffer amps and “for kicks” an ATTiny816 MCU: I wanted something to drive a ‘neoled’ chain.

Many thanks for your interest and please let me know how I might assist you.


#2

I’l, add in the main part of the schematic, too:


#3

It looks very well done at first glance. One thing I noticed was the difference in annular rings on the header pads, is that just because of ground fills? It might be worth giving them thermal relief in that case.

I think to do a proper review we need the files or at least to see the back side of the board as well.

One thing I like to do, if the stakes are high, is to print out the layout on paper, buy all the components and “populate” the paper board to check the footprints.


#4

Hey kashah, thanks for your thoughts.

The annular ring thing is just because those pins are connected to the (solid) ground plane so there is copper where there would normally be resist. I am not really aware what a “thermal relief” does or why you would use it… could you explain?

I will have to fund manufacture personally, so mistakes aren’t welcome, but most components are relatively cheap; the most expensive is ~£12. I’m hoping to get a company to assemble it, as I am not skilled in SMT work and this is pretty small (circa 3x2").

The one thing I am pondering is making a “model” of the pcb to check that the headers and outline will actually fit on the beaglebone. I have access to a simple CNC machine, so wondering if there is an easy way to turn the pcb outline + holes into something a CNC package could use?

I’d be welcome someone looking at the project files, but am unsure which files to package and how to make them available here… would the kicad_pcb + .pro + sch files be sufficient or would I need the other libs and stuff too?


#5

The references to annular rings, and thermal relief, refer to the leftmost four pads on the upper header strip, and the top-right pad (pin 1?) of that same header.

Look at this link: https://electronics.stackexchange.com/questions/76402/does-adding-thermal-relief-on-pcb-increase-electrical-resistance

About half-way down the page is an image showing two pads, each located in (and connected to) a copper pour. The pad on the left does NOT have thermal relief. We might also describe as having “direct connection” to the copper fill zone. The pad on the right DOES have thermal relief.

In general, pads WITH thermal relief are easier to solder. This is especially true when hand-soldering but may also affect solder-joint quality with some reflow- or wave-soldering processes. (That copper pour is still a large thermal mass regardless of how you try to solder to it.)

If you don’t want the assemblers on the manual soldering line to make derogatory remarks about your ancestry you will specify thermal reliefs for pads connected to your copper pours. In KiCAD, this is done by the “Default pad connection” parameter in the “Copper Zone Properties” dialog. (Hover your mouse cursor over the zone’s outline and press “E”.)

Dale