provide a few spare pins that you can watch on a scope
and, if you, like me, have found out that the weaker your eyes get, the smaller the components get, pull them out to a pad. BTW that pad does come in mighty useful if you have to make a "forgotten" connection to a piun.

if your chip has JTAG debug, provide access to it! For production, you could just not fit the actual connector - but keep the access there.
The connector is dirt cheap and you WILL find a few returns that puzzle you as to why they do not work. Put the connector on all units. BGTW t5hat also can serve as a field upgrade connector.


have the facility to write debug "trace" messages to a serial port.
Maybe in some extraordinary cases this could be useful; however "debug by serial" always upset tha applecart timingwise more than it helps.


set aside some memory for statistics recording, post-mortem info, etc - and provide a means to access it!
absolutely and the ICE makes for the access.

Erik