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SPY-BI-WIRE PROGRAMMING PROBLEM

Other Parts Discussed in Thread: MSP-TS430PW14

Hi, everyone:

I am using a MSP-TS430PW14 target board and a MSP-FET430UIF emulator to program my MSP430F2XXX mcu.

Jumpers (J7~J12) on target board are set between 1and 2 to use Spy-Bi-Wire programming. (See slau278e page 36).

Jumper J5 is also close on 1 and 2 for taking power from debugger. 

However if I remove jumper cap on J5, the mcu can still be programmed. (which mean Vcc pin on mcu is floating).

I am confused how is the debugger able to recognize the mcu and program the flash.

Does any one have any clue ?

 

 

 

 

  • MSP430 needs very low power. The SBW connection may "leak" enough current to your F2xxxx to run. This may be marginal and is not a reliable way to power the F2xxx.

     

  • old_cow_yellow said:
    The SBW connection may "leak" enough current to your F2xxxx to run.

    More precisely, if the coltage on any input pin, including the JTAG pins, exceeds VCC by more than 0.2V, current will flow from this pin to VCC, powering the device until VCC equals the voltag eon the input pin minus 0.2V.

    The maximum continuous current through each input pin is 2mA. The MSP itself does not consume that much, but other attached peripherals may, including the flash controller when erasing/writing. But then, there are more than one inpout pin and the higher current is only for short periods. There's stilla risk of damaging the clamp diodes by overcurrent, and once these are gone, destruction of the input pins may follow.

    however, the JTAG pins should be equipped with serial resistors limiting the current through the programming lines. It's still something outside the specs.

  • Thank you ! It helps a lot