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msp430FR5849: JTAG / SPI By Wire Connection Issue

Part Number: MSP430FR5849
Other Parts Discussed in Thread: MSP-FET


I have a customer who is just bringing up his MSP430FR5849.

He has a new USB debugger and his own board.

All his prior experience was with the i204x.

He cannot debug and gets an error "device unknown"

I had him check his project and it is the correct device.

I used to have issues with SPI by Wire not being selected in CCS and the debugger defaulting to JTAG, however, this no longer seems to be an accessible setting to change.  I am assuming it is smart enough to try both.

He is using an external power supply.

I checked his part decal (QFN) and he seems to have all the pins going to the right spots.

Instead of the normal 47K on RST and 1.1nF he has:  3.3K Pullup on RST, 2.3K Pulldown on TST and no capacitance at all on either pin.

Any ideas?


  • Hi Blake,

    Are they using the MSP-FET tool? Can you share schematics or layout images online? I know you already checked this but make sure their connections are in accordance with Figure 2-3 of SLAU278. CCS can determine what interface to use, the VCC will connect to pin 4 since they are using an external supply. They should try using the recommended 47 kOhm pullup and 1 nF pulldown on the RST line.

  • Changing the resistors fixed everything from his initial values...

    Thanks for the help - we can close this out. We tweaked his linker file and it works too now.

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