Both my microcontrollers on my project (dsPIC33FJ128GP804 and PIC24FJ64GA004) support JTAG boundary scan testing. Should I wire these up and expose a JTAG port for hackers? The product is intended to be open hardware and as such be modified. ICSP and ICD ports will also be exposed. Of course these ports and traces take up space - so is it worth it? Would people be able to use them with basic PIC micros?
These pins will surely be needed for the firmware debugging/loading.
You could always bring them out onto a section of the board that can be snapped off before delivery/installation. This means that the developer has access to the connector/debug interfaces that are absent from the final product. If you place the debug traces on an inner board layer then this will make the hacker's life more difficult but, assuming that you have not disabled the JTAG in the processor, they will always have access to the device pins and so to the interface.