MSP-EXP430FR5994: 5 V Power Supply

Hi Adi,

This sounds like an in-rush current issue. Are you connecting your hardware to the MSP-EXP430FR5994 while the MSP-EXP430FR5994 is already connected to your computer? I'm assuming that the error you mention is on your host computer. Usually when I come across issues like this with USB platforms, it's related to a board charging up its bulk and decoupling capacitors rapidly, causing a brief transient voltage dip on VBUS that is significant enough to cause the eZ-FET emulation circuit on the LaunchPad to lose enumeration with the computer.

This issue tends to be more prevalent when you have sudden current variations (large dI/dt events) while the LaunchPad is already enumerated to the host computer. I would like to know if your hardware works correctly if you attach your board to the MSP-EXP430FR5994 before connecting the MSP-EXP430FR5994 to your PC. In this way, your board and the LaunchPad come up together and generally the inrush current is better tolerated. If there is still an issue, you may want to closely capture traces of VBUS at the LaunchPad connector. It's also worth looking at how much bulk decoupling capacitance you have on your board. I've seen 10uF or 20uF of ceramic chip capacitance cause issues on VBUS before when connected.

I might also have suspected a short somewhere, but you ave already checked that your levels are quite good so I do not think that is the case.

Regards,
Walter

I agree with Walter. I had some similar issue and it was related to a transient on VBUS.

You should be able to isolate the 2 circuits (yours and the MSP-EXP) with a simple L-C or better C-L-C pi filter on the 5V input of your circuit. It should resolve your problem.