So i presume P2 is the JTAG for the GPU, used to load the boot code and none of those pins are accesible from the ARM to be used as another GPIO.It is also possible to reconfigure GPIO connector pins P1-7, 15, 16, 18, 22 (chipset GPIOs 4 and 22 to 25) to provide an ARM JTAG interface.
No, that does not work. You can reset the JTAG logic only.hippy wrote:P2 pin 2 is TRSTN which may provide a means to reset / reboot the whole kaboodle from a push button or some other logic signal without having to cycle power. It may be possible to hold in reset to reduce power consumption rather than switching the supply.
I'm not experienced with ARM hardware and it would need someone to conform or try both.
I have jtag working on the Raspberry Pi debugging using the ARM processor debug port. It is not the P2 connector as folks have already figured out. But not everything is on P1 either. seeMorgaine wrote:Actually JTAG is a nice thing to have even for mere mortals, as long as it is used with caution and some commonsense. The Pi community is very likely to make use of one or both of the JTAG connectors in due course, as it will assist in debugging of programs with the help of an external development system as is done with any other embedded board. It would be especially valuable for driver development I think.