Close

Starting the Design

A project log for One Tube Nixie Clock

It is time to take my nixie hardware testbed from the breadboard stage to something that doesn't have wires sprouting everywhere.

paul-andrewsPaul Andrews 11/20/2017 at 15:570 Comments

Define Some Libraries

Time to start putting some footprints and symbols together. My workflow for this is to define the device (symbol and footprint) in Eagle and then convert it to KiCAD using Eagle to KiCAD libs, to which I have contributed quite a few modifications. My main reason for this is that I use KiCAD for my circuit designs, but there are way more libraries for Eagle.

I have two new parts I need libraries for (I already have libraries for everything else):

I couldn't find any existing Eagle libraries for these, so it was time to create my own.

The first is a 7mm QFN-44 chip. I need to get that size right! In one of my earlier iterations of a USB-UART adapter, I didn't release that QFN-28 came in a couple of sizes and I fabricated some boards with the wrong size. Fortunately I found a footprint in an ST-Microelectronics library that I already had. I imported it into my own library and modified the size of the center tab to match the Microchip datasheet. Then I duplicated a symbol for the HV9808 that I had already defined, modified it a little for the HV5523 and hooked everything together.

The second is a VQFN-14 - at least that is the version I will be using. I couldn't find this in any library I already had, but a quick search turned one up in SnapEDA. I downloaded it and imported it then checked the dimensions against the TXS1040 datasheet. It was a match, so then I quickly defined a symbol and hooked them up.

Then I double-checked the dimensions, the connections and the pin directions. OK. Good to go, so convert it using Eagle to KiCAD libs and it is ready to use in KiCAD.

Start the Board Design

My board will use sub-circuits from other experimental boards I have already built (with a few modifications). Namely:

I have never used hierarchical sheets in KiCAD before, but it seems like a good time to start. Coincidentally, it also seems like this is the only way to copy those sub-circuits into a new project with the version of KiCAD I have (4.0.6). Copy and paste just don't work. I followed the procedure outlined on this post by padu1000. I'll reproduce the text here, but it I have modified it slightly:

So now, just add the new symbols and wire them up to the sub-circuits :-)

Discussions