RE: BMW Navigator 6 - Update New MacBook - 2

That makes sense. Linus Tech Tips did a video on a $1,000 cable tester. Set it up, plug in a cable, and it stress tests every wire for communication and stability. Only way he has to know if a defective cable is to blame for a hardware issue.

https://youtu.be/XFbJD6RE4EY

The fifth wire you mention is the ID pin, this is used to signify the connected device is the host. From my background reading it seems this configuration is rarely used. The spec is not clear on where/when it's necessary to utilise this pin. I've yet to find a cable or USB adapter that works with my combination of MacBook Air and Nav VI.

As I already mentioned in a previous post I am able to connect my old Garmin LM390 to my Mac Book. This GPS uses the older style mini A USB connector. I wonder if there is a connection to the mysterious fifth pin. I've just checked the spec and this is Pin 4, designated as 'Mode Detect'. When used, it's connected to GND, this indicates a HOST is present. I'm unclear as to when this is necessary, I wonder if this is significant? I did request a pin allocation drawing from both Garmin and BMW for the power/data connector. Garmin state this information is not available, BMW do not seem to have this either. It's not shown in the users handbook either.

One other point worth noting is that some applications show the D+ and D- pins being terminated via a 10K ohm resistor to GND. My guess is that this damps down any ringing on the data lines. I can imagine that as data speeds ramp up as per the USB C using devices' EMC effects become a critical issue. I think the only way to clarify some of these issues will be build a breakout test fixture so that the actual pinout can be ascertained. These small contact pins are very difficult to buzz out for simple continuity tests.

So much for a universal spec that everyone complies with. There's not even any part marking of the cables to signify differences. I hate being beaten by such a simple interface.

Zitat von wessie im Beitrag #17

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Original usb was 4 wires, 2 power, 2data. Usb 2 has a 5th wire possibly significant but not read the full spec, but most likely the missing data wires as said above

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