Extension Connector

[sgehrs]

If the extension connector is soldered to the bottom of the board as shown in the assembly instructions, don't the rows of pins  get swapped? That is pins 1 - 20 are where pins 21- 40 should be? It appears to me that they do.

Ok I thought about it for a while, and the connector is to connect another board with a ribbon cable to a male connector that changes it again to the expected pin order. This came up  for  me because I have Tontec 3.5 LCD display that plugs into the expansion connector, and the little pcb board the connector is soldered to interfered with the power switch. So I thought I'd just plug into the expansion connector. Fortunately I looked at the pinout first and didn't hurt anything. But someone is going to try to plug a hat directly into it and destroy something.  There should be note in the assembly instructions describing what that connectors purpose is.

A little paranoia before plugging something in for the first time can save a lot of time and money.

Steve

[Felix]

Your observations are correct. The 2 headers on the MHat are not mirrored, but parallel. So first header on the inside of the board is 1:1 with the Pi Header, then the second header (near the top outer edge of MHat) is also 1:1 with the Pi header, looking from the top. IOW [row 1 and row 3], and [row 2 and row 4], are the same.

The outer header was provided for flexibility in soldering another header any way you want. You can solder it below or above, straight, or right angled, male or female. Not too many hats offer something like that. Of course you have to be aware that the actual rows get swapped depending how you actually solder your extra header.

I hope this makes sense.
I tried to make it as plain as possible to use, and I plan to add more documentation for the MHat.