On Tue, May 26, 2009 at 7:47 PM, Magnus Lundin <lun...@mlu.mine.nu> wrote: > Spencer Oliver wrote: >>>> >>>> If you define your interface with only srst then the >>> >>> software method >>>> >>>> will be used. >>>> Well it did last time i checked - see jtag_add_reset for code. >>>> >>>> >>> >>> That code makes a move to TLR. This method is fine when you know in which >>> state you are, but not when OpenOCD is started and the previous TAP state is >>> undefined. >>> >>> >> >> I have not dug into jtag.c for a while, i am pretty sure it was not the >> case. >> it was a few years back however that this support was originally added. >> >> Cheers >> Spen >> >> _______________________________________________ >> Openocd-development mailing list >> Openocd-development@lists.berlios.de >> https://lists.berlios.de/mailman/listinfo/openocd-development >> > > move to TLR works for all current states. It is 7 steps with TMS high, that > takes you to TAP_RESET froma any starting state.
Moving to TLR from an *unknown* state doesn't work because we pretend that there is no such thing as the TAP being in an unknown state. We rather initialize the boot state to be TAP_RESET. Which is not only false but also leads low level drivers to believe that nothing needs to be done. In particular the ft2232 driver says statemove TAP_RESET -> TAP_RESET is redundant and does not need to be executed (see ft2232_execute_statemove() ). Michael _______________________________________________ Openocd-development mailing list Openocd-development@lists.berlios.de https://lists.berlios.de/mailman/listinfo/openocd-development
