The SCM20260N is a drop in replacement for the G120 with the following differences…
( From https://docs.ghielectronics.com/hardware/netmf/upgrade.html )
So only 4 points of difference and for my upgrade I only had to change the connection to the UART used for serial debugging, which was great because I didn’t even need to get a new stencil cut as none of the components moved.
Except I found another difference. Unlike the EMX and G120 where the device starts with IO ports as inputs with pull-ups, on the SCM20260N they come up as high impedance. This impacts on three areas of my circuit, which have worked since the first EMX version. Once of these is the power-on latch, so without the pull-ups the board won’t even start - the 3.3V turns off as soon as you release the on/off button. Another is the emergency power-off circuit, where Left, Right and Up buttons connect to a 3-input OR gate. Without the internal pullups the board shuts down if you press Up. And the last is a startup LED, which indicates 3.3V power is up but the processor hasn’t gained control.
Not a big issue, I just had to do a board revision to pack in another three pull-up resistors (and a new stencil), but i think it would be a good idea to add this difference as a fifth point of difference in the documentation.