Making the doco clearer for newcomers


So I have just started really trying to put the Macchina M2 to work and I think it is really great. I would say that some clarification in the documentation would help those who have not seen the thing before.

Put in the instillation part of the Macchina Docs a mention of the fact that you need to connect at least one of the Digital grounds and +12V INPUT (pin 23 of the 24pin plug) to get the thing to work. I spent some time with just the CHASSIS GND connected and nothing…
Is the CHASSIS GND even connected on an UTH M2? The schematics are not clear.

There should be mention in the Getting Started section where you can find the pinouts for the OBD2, 24pin UTH socket and the 26pin “Expansion” connector. This is especially important for people with the UTH version.

In the section on Power could I suggest that you mention which pins on which plug you need to supply 5V @ 3 Amps and 3.3V @ 1 amp. Is that +5V on pin 20 of 26pin plug and +3.3V on pin 23 or 26pin plug? Looking at the schematic that appears to be correct but it would be nice for people to know what they need to do.

In “Low power options” what are “+12V_SW” and “+5V_SW” used for? Again from the schematic it appears to be just for the J1850 interface but it would be good to just say if you are not using J1850 then set PS_J1850_9141 low.

Thanks for an awesome device :slight_smile:



Chassis ground is connected but I think through a 1M ohm resistor and a small value capacitor (So, through an RC filter). It’s meant for noise immunity and not to power things.

But, yes, I agree. I’ve had an M2 about as long as anyone could have had one and I still get a bit confused about the pinout for the plugs sometimes and have to try looking it up. I wish there was a single page with all the pinouts for every connector on both versions of the M2. Right now the info is spread across pages. So, I think it’s a good suggestion.