I was keen to take a look at how the ArduSub development was progressing, but keep hitting this error when compiling:
fatal: reference is not a tree: 3b960549601cc22b7bbaa89257833f8d9053e491
Unable to checkout ‘3b960549601cc22b7bbaa89257833f8d9053e491’ in submodule path ‘…/modules/PX4Firmware’
I’m using the method described here: http://dev.ardupilot.com/wiki/building-px4-for-linux-with-make/
but also hit the same error when using Windows to build.
Is there another step I’m missing somewhere?