Am 06/10/2011 04:35 PM, schrieb Laurent Gauch: >> >> If I quit OpenOCD, I expect the target to stay in the same state as >> before. >> If it was in reset, I expect it to stay in reset and not start some code >> uncontrolled. >> > > Yes you're right Michael regarding the state of the TARGET. > > Did you already have needed to have SRST to be assert low at the end > of the openocd to force the SYSTEM RESET on the target board ? > If yes, putting systematically all signal to High-Z at the output of > the dongle could be a trouble. > But I am not sure it is the 95% of debugging/programming case.
It is not just reset. If we agree that we do not want to touch the target, that means the lowlevel interface driver must not change any signal state upon exit, because it does not know what state that will put the target into. Changing signals to High-Z is *not* safe. It changes the JTAG signals to a board-specific state that depends on the pullup/pulldown resistors on the board. Depending on the old state of the JTAG pins, this may cause a clock on TCK, with random values on the other pins. Why would we want do do that? What is the problem with leaving the signals in just the state that the upper OpenOCD layer (which *knows* about the target) left them in? cu Michael _______________________________________________ Openocd-development mailing list Openocd-development@lists.berlios.de https://lists.berlios.de/mailman/listinfo/openocd-development
