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Using shared pins for JTAG and SPI on the MSP430F2003


This is my first time using thie above part, the JTAG pins aare shared with the SPI pins. Is it possible to use a debugger and the SPI interface at the same time ? or must I program my part then disconnect the JTAG in order to use the SPI interface ?

Any insight would be appreciated.

Thanks in advance,

Aidan Browne

  • Most MSP430 pins are multiplexed, so some tasks using pins mulitplexed with JTAG functionality may be unavailable during a debug session.

    An example is the P1.6/TA1/A6/SDO/SCL/TDI/TCLK pin for the F2012. Let us say you want to use the TimerA or ADC funtionality of that pin. This pin is also needed by the emulator tools for 4-wire JTAG debugging, so this code will have a conflict in normal debugging mode. However, you can run this code with the tool connected and see appropriate functionality if you choose "Release JTAG on Go" under the Emulator menu once you enter the IAR debugger. This will release the JTAG lines and allow the code to run normally.

    Please note in this case you cannot continue debugging as the tool has released control of the MSP430.

    An exception to this is using the RST/NMI pin for the NMI interrupt function. The code will still run when "release jtag on go" is set but since the RST line is connected to the JTAG it is being held by the tool such that an edge necessary for an NMI interrupt cannot occur by using the target board pinout. Thus proper results may not be seen.

    In this case, meaningful output won't be seen by this code unless you disconnect the board and are then able to provide an appropriate edge.

  • The SBW version of JTAG can be used with less contention.

  • Hello Browne,

    I would suggest to use Spy bi wire in combination with  a USB-FET or the Easy. IF you use Spy bi wire connection you just need pin 10 and 11 for debugging propose.

     Regards Florian