It simply works!

[Piotr]

@RaptorUK

When the pandemic hit we were working on a new product with a couple of small, but busy PCBs (Motor drive, RS485 comms, MSP430 MCU, etc) when this failed EMC testing I made some significant layout changes including going from 2 → 4 layer using KiCad and we now have passed EMC.

Do the RS485 was the source of EMC problems?
RS485 drivers can have different common mode voltage when sending 0 and 1. It can happen that one IC have no difference (no EMC emission from this reason) and other have 100mV difference what is a lot.
They also change one output stage faster than the other one what generates common mode peaks during changing state and is also a reason of emission.
This is why in theory RS485 is not 2 wire, but 3 wire interface.
I am using 4.7mH common mode choke on RS485 (115200) lines.

The other problem is when you use isolated RS485. DCDC used to power isolated side can be the source of EMC. Also modern signal isolators (not transoptor) can generate CM noise.

[RaptorUK]

@Piotr

Do the RS485 was the source of EMC problems?

Nope, it was the output from the H Bridge to the motor causing radiated emissions;fixed by a Common Mode choke up at 34MHz and also back as conducted DC emissions; fixed with a pi filter down around the 500kHz area. Could see all the 20kHz harmonics on the spectrum analyser.

The whole thing is a bit of a pain as we don’t have a proper 0V to the PCB

[paulvdh]

@RaptorUK

We asked for an alternative solution for us to get access to our data and were told . . . "Altium is your best option . . . " yup, at £10k a seat we weren’t too impressed.

There are quite a lot of people complaining about altiums pricing policy on EEVblog.

Altium Price Rises - Page 1

Massive price hike on A365 coming in Jan - Page 1

Altium is killing off perpetual AD - Page 1

[nickwest]

Perhaps your employer should think about paying a few pounds to the Kicad team.

[davidsrsb]

@TheSwede

The .wrl format (which often is the chosen format in the kicad libraries, even if the step files are also included in the libraries, don’t know why they have chosen this way)

Historical. Back in what you would call V3 times, KiCad was almost pure wrl for artistic rendering. It was the FreeCAD partnership that drove STEP as the better model, as mechanical CAD need precise dimensioning. Until recently FreeCAD and STEP were rather poor at detailed face colouring

[TheSwede]

Thanks for the information, davidsrsb.

[RaptorUK]

@nickwest

Perhaps your employer should think about paying a few pounds to the Kicad team.

100% agree and I will be broaching that exact subject in due course . . .

[supton]

paulvdh, there’s plenty of complaining about pricing the Altium forum itself! I only glanced at the complaint thread on EEVBlog once (not active there) but the complaining is on the Altium forum also, with more than a few saying they’re done now.