KiCad notes: The one-timer PCB maker’s hints for the next time

Intro These are my notes to self for the next time I’ll have a PCB design to make. This is definitely not my expertise. My original intention was to start this post with some kind of apologize, saying I only needed to make a simple board, so KiCad was good enough for this purpose. However [...]

PCB layout: Selecting the track width and spacing for a differential signal

Introduction Even though this is definitely not my expertise, I made a simple adapter board carrying USB 3.0 signals. The name of the game with such boards is to make a minimal impact on the signals, which means, among others, selecting the attributes of these two pairs of differential lines (SSRX and SSTX) in a [...]

KiCad PCB layout: Adapting the footprint’s pads to match track width

Introduction It just so happened that I went for a pair of 0.8mm thick wires, with 0.2mm between them, in order to achieve 90Ω differential impedance on a 1 mm thick FR4 board. No wonder PCBnew (KiCad’s layout program) refused connecting these wires to a USB SuperSpeed receptacle’s footprint, with its 0.4 mm side pads, [...]

USB 3.0 device compliance test notes

Introduction While implementing Xillybus‘ USB 3.0 general purpose IP core for FPGAs, I found the USB Implementers Forum’s compliance tool handy, yet somewhat quirky, for verifying I got things right. It was USB3CV version, running on Windows 10 @32 bit. The 64 bit version works the same (I’ve tested it as well). A GPLed [...]

+5V voltage feed on HDMI cables and a failing HDMI2AV converter

After quite a while of working perfectly well, the mini HDMI2AV module I have (in the picture above, mentioned in this post) started producing an unstable picture, and in the end a completely garbled one. It took some time to nail down this specific component in the foodchain, because there was also an HDMI splitter [...]

EDID info from mini HDMI2AV module (HDMI to RCA CVBS)

This is the information obtained with xrandr from the HDMI to AV converter  (Composite Video + Audio on RCA plugs) shown above: Screen 0: minimum 8 x 8, current 1280 x 720, maximum 32767 x 32767 DP1 disconnected (normal left inverted right x axis y axis) DP2 disconnected (normal left inverted right x axis y [...]

Hierarchies in Orcad schematics: Please, don’t

It seems like hierarchies are to board designers what C++ is to programmers: It kills the boredom, but also the project. They will proudly show you their block diagrams and the oh-so-ordered structure, but in the end of the day, noone can really figure out what’s connected to what. Which is kinda important in a [...]

When TI’s CDCE62002 fails to lock

I really banged my head on this one: I was sure I had set up all registers correctly, and still I got complete garbage at the output. Or, as some investigation showed, everything worked OK, only the PLL didn’t seem to do anything: The VCO was stuck at its lowest possible frequency (which depended on [...]