I’m a happy user of KiCad PCB. On MacOS a lot of things are still buggy, but I found ways to work around these bugs. But today I found a really nasty one. On my HiFiBerry DSP Light PCB, KiCad did not correctly create thermal relief zones.
Let’s have a look at this PCB design:
Looks good. The two tracks to the capacitor on the left side do not overlap any other tracks. But what happens if we fill the ground zone?
Grrr! There is clearly a connection now between the ground pane and the N-0000011 track. But there is an even bigger problem: If you run the design rule check now, KiCad does not think, this is a problem. Therefore, I did not notice it before soldering everything.
Finding this connection took me some hours. Fortunately the chip was robust enough to survive this short circuit, because replacing an LQFP package is not one of the jobs I really love to do.
I agree, that there are a lot of Raspberry Pi related postings in the last time, that do not look like audio related postings. But I can tell you – they are. We’re working on audio projects for the Raspberry Pi. The goal is to have a high quality sound system based on a Raspberry Pi. One thing, that we could not find somewhere, was a simple template for a Raspberry Pi extension board. Therefore we created one. The board size is the same 85x56mm as the Raspberry Pi itself and it includes the extension headers P1 and P5. P5 is especially important for audio, because that’s the I2S header. The template is available freely on Github.
I’ve started working on the DSP module. Unfortunately, there is no KiCAD library for the ADA1442. Therefor I created the module by myself. You can download it here: ADAU1442 Kicad Library.
You don’t need an extra module, the TQFP-100 package is supplied withe the KiCAD standard libraries. However the ADAU1442 has a thermal pad on the bottom, that is missing at the KiCAD module.