MSP430F5659: Schematic Review

Hi Brian,

I have 2 comments.

First, make sure the T_RST (RST/NMI/SBWTDIO) node has a 47K pullup resistor to 3v3 and a 1nF to gnd.  I didn't see one on this schematic.

Second, it appears R137 (1M) resistor is connected incorrectly.  It should be connected as shown below.

Here is link to USB hardware design guide.

Everything else looks ok from my perspective.

From customer:

We are using an external watchdog / reset circuit and it has a pull-up / cap in it. Thank you for catching the wiring issue with the 1M resistor! Would it be possible to double check the updated circuit below? Please note that VUSB is connected directly to 3V3 since we plan to use an external regulator.

Since the switch at PUR is needed to support USB-based boot loading, how does external boot loading work, since the PUR signal is not externally accessible?

Easiest way to use factory preloaded HID BSL, is to have RESET and PUR button. Press both, first release RESET and after this release PUR button. This will trigger entering to BSL. If device is mass erased (blank reset vector), it will enter to BSL mode by default, without buttons.

Thank you, I will pass along. I also forgot to attach the updated schematic, let me know If it looks good:

Hi Brian,

Zrno is correct regarding the steps to place the MCU into BSL mode, so having a button for both RESET and PUR would provide this capability.
Regarding the updated schematic - looks great!
Since you have VUSB tied to your +3.3v, make sure the MCU's VUSB LDO is disabled in code.
Good luck with your project.