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CAPTIVATE-PGMR: Program custom board with MSP430FR2676

Part Number: CAPTIVATE-PGMR
Other Parts Discussed in Thread: MSP430FR2676, , ENERGYTRACE

I have a custom board which contains the MSP430FR2676 MCU on it. I am powering the MCU locally using a 3.3V LDO on the custom board. I used the 20-pin CAPTIVATE-PGMR on the custom board to program the MSP430 using 2-wire interface. While I am able to program the MCU, I notice that if I unpower my board but leave the CAPTIVATE programmer hooked up, the programmer powers my board via the VCC_TARGET pin which is pin 18. Below is a capture of the programmer header according to the CAPTIVATE-PGMR design center note, which shows that pin 18 is a target vcc pin (or so I assumed). According to the CAPTIVATE-PGMR schematic, pin 18 is an output pin (supplied by a 3.3V LDO). Since I am powering my board locally, should I leave pin 18 disconnected to avoid this reverse power situation? Does the programmer require a VCC_Target reference or is that fixed on the programmer at 3.3V? The design note doesn't make this clear.

Below is the programmer header portion of my schematic showing 3V3_MSP on pin 18. This net is supplied by a local 3.3V LDO which supplies other peripherals as well. So again my question is should I disconnect 3V3_MSP from pin 18?

Thanks in advanced for the help!

  • Hi Luke,

    Since your board is self powered, no you don't need to connect pin 18 on the programmer.  The Captivate programmer provides a 3.3v LDO output on pin 18 primarily to power the Captivate MCU boards. There is also a 3.3v metered output pin, which comes from the energyTrace DC-DC converter that is also on the programmer board and is used for measuring the target device's current in Code Composer Studio.

    Technically, to program/debug your target hardware you only need the 2 SPY-BY-WIRE pins (SBWTCK_TST and SBWTDIO_RST) and ground.  But when designing capacitive touch interfaces, customers will typically design a 5 or 6 pin connector and connect the SBW pins, ground and either UART or I2C signals so they can communicate with the Captivate Design Center during sensor tuning and development.

  • Thank you so much Dennis! 

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