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Jtag pinning versus ICSP

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emblocks
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2012/12/29 00:11:39 (permalink)
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Jtag pinning versus ICSP

If I use in a design only the jtag port (the ICSP pins are used for other purposes) and somebody (me) uses by accident a microchip example which is disabling the jtag. How to get that board out of his autistic state?
 
Is there a way or do I have to use the ICSP? If so then that is very dangerous. And if so wouldn't it be smarter for MCP to map the ICSP pins on the JTAG pins?   

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    RISC
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    Re:Jtag pinning versus ICSP 2012/12/29 04:06:13 (permalink)
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    Hi,
     
    Look at the PIC32 starter kits schematic.
    As far as I remember, the on board PIC32 "tool CPU" uses JTAG for programming and debugging the "application" PIC32 ;=)
    I mean, the PIC32 "tool CPU" (kind of "Pickit3" functionality) is connected to PC using USB device and connected to "application" PIC32 using JTAG.
    This kit only operates in debugger mode even though the application CPU can execute code once the PIC32 "tool CPU" is disconnected from PC (and hence from MPLAB X).
     
    Regards
     
    #2
    emblocks
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    Re:Jtag pinning versus ICSP 2012/12/29 13:07:00 (permalink)
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    Hi,
     
    The debug interface chip is connected both on the ICPS and the JTAG (if I'm right).
     
    One possibility is that the pic32 jtag target driver is checking the config and refuses all the config settings which could lead to isolation.
     
    Regards

    Em::Blocks free IDE with PIC18/24/30/32 support
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    #3
    andersm
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    Re:Jtag pinning versus ICSP 2012/12/29 15:06:17 (permalink)
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    I'm fairly sure that configuration bit only takes effect once the device is released from reset, like how any ICSP pin pair can be used for programming the device regardless of the value of the ICESEL bits.
     
    By the way, there's a series of patches in the current development version of OpenOCD that are supposed to significantly increase JTAG performance for MIPS M4K cores.
    #4
    emblocks
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    Re:Jtag pinning versus ICSP 2012/12/30 01:34:23 (permalink)
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    Perhaps that is true for the ICSP  but not for the Jtag.
    This information is also available at the jtag adapter sheet from MCP. You can go from jtag to ICSP with no problems, from ICSP to Jtag you have to erase the chip first.
     
    I couldn't make contact but first to have erase the whole chip (TDOEN was giving problems).

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    emblocks
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    Re:Jtag pinning versus ICSP 2013/01/04 08:41:04 (permalink)
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    andersm
    By the way, there's a series of patches in the current development version of OpenOCD that are supposed to significantly increase JTAG performance for MIPS M4K cores.

     
    How fast (or slow) was the previous version?  I use the 0.6.1 version (can't find any changes in the sources from the GIT) and this version is even with a JLink on 12MHz very slow.
    A single step takes ages.  I see that the TCK goes at 12MHz but the queries are going in bursts of 6 mS.
     
    A single step is doing a lot and at the end it is asking the reasons why it stopped with a lot of instructions writing into the jtag chain (with that low speed burst intervals).
     
     
    I also tried the jlink with openocd and a MCB1700 board and that speed is also a bit disappointing if you compare it with the native segger GDB server.
    Perhaps I have to much expectations or something is completely wrong here (linusb-win perhaps???)

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    andersm
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    Re:Jtag pinning versus ICSP 2013/01/04 09:32:51 (permalink)
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    The patches are not in any released version yet, you'll have to compile it yourself from git. 115b7b is the first commit of the series.
    #7
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