Monday, February 27, 2017

KiCad schematic and board

Over the weekend I finished up the schematic for the nRF24LE1 programmer. Here's a screenshot:

The thing I miss most from Eagle is the ability to highlight a net (wire) to verify that I've named things properly. For example, the named net VCCIO appears in three different places in this schematic, but there's no easy way to find all of the segments or verify that one of the three hasn't been mistakenly labeled VCC10. The suggestion I found online was to export the netlist and look to see that all parts are connected to the correct net; that's nearly as stupid as the other suggestion of looking at the board layout and checking the airwires. The program should do this for me!

The other thing that's most annoying is that they make it extremely difficult to create a new symbol or footprint library. This should be an item on the File menu in the library editors, but it's not.

Yet another annoying bit is that the footprint libraries are device type specific. There are a set of footprints for SMD capacitors, another set for SMD resistors, yet another for SMD LEDs... yet all of these come in standard footprints. If I have device that comes in an EIA 0603 package, it doesn't matter whether that device is a capacitor, a resistor, a diode, or a ferrite bead. If a device requires a different footprint it's because the device is non-standard, not because it's a capacitor rather than a resistor.

Having managed to create a new schematic symbol for the FT232R, and new PCB footprints for the Mini-USB B connector and the ferrite bead, I proceeded to start the PCB layout. This is pretty easy, once you get used to grabbing components with the "m" key on the keyboard rather than a mouse button. Here's the initial layout:

The component layout isn't final. I've only partially routed one circuit, and that only to see whether I could route a circuit between the pads of my USB connector footprint and pass the DRC. This led me to discover another annoyance of KiCad: when you configure the net classes they become the ONLY trace widths KiCad will lay down. I started with only the default class, configured for the minimum width of 6 mils, and was frustrated by not being able to select a wider width. I need to look into this issue; maybe there's a way around it.

No comments:

Post a Comment