Patrick Wieland wrote: > So the JTAG-debugger needs an input pin attached to RTCK. OpenOCD has to > monitor the state of this pin an wait for a falling edge. When this has been > detected, OpenOCD can generate the next clock tick, resp. rising edge on > TCK.. > right? Is this that what the Amontec Chameleon Dongle is doing in source file > 'amt_jtagaccel.c' function 'amt wait scan busy()' ? >
Be careful with your terms, it is the "jtag dongle" that needs the input, and the 'jtag dongle" needs to be told to use/honor the signal. The "jtag dongle" generates the JTAG clock, the synch circuit in the target chip, throttles the clock frequency. There is no *debugger* there. Instead, the debugger is GDB.. the debugger GDB "connects to" openocd - which then controls the jtag dongle, which in turn controls wiggles pins on the jtag interface. I think you are *buried* in the details. 1) gdb <- This is the debugger. 2) gdbremote-protocol (via tcp/ip) 3) openocd (application) 3) often a usb interface (sometimes parallel port) 4) if USB - often a ftdi-chip is used <-- This is the "jtag dongle". 5) In your case, "1.2v level shifters" 6) the "jtag tap" on your chip 7) the "arm cpu" you want to control and debug your code with. But to answer your question ... Yes, a pin is needed. This is handled *automagically* by the FT2232H chip, you only need to enable it. The ftdi-2232-H monitors the RTCK signal on GPIOL4 See: http://www.ftdichip.com/Documents/AppNotes/AN_108_Command_Processor_for_MPSSE_and_MCU_Host_Bus_Emulation_Modes.pdf Section 6.9 -Duane. _______________________________________________ Openocd-development mailing list Openocd-development@lists.berlios.de https://lists.berlios.de/mailman/listinfo/openocd-development
