MSP430 restarting.....

abhishek Sabnis

Other Parts Discussed in Thread: MSP430G2452

I am using MSP430G2452. In my application at certain event i drive MOSFET LOW (with P1.1 I/O port with output configuration) which intern shuts the regulator off. The same regulator is supplying MSP430 3.3V. So what i am expecting is when i drive MOSFET low MSP430 should Die (turn off). but in reality when supply to MSP430 starts to go down from 3.3V to 0V it gets restart pulse, which in tern turns the MOSFET ON and again low hence, its gets into never ending loop.

Question is why MSP430 restarts back when i want to turn it off?

Thanks

over 13 years ago

0 old_cow_yellow over 13 years ago

Guru 58965 points

Please check the data-sheet and User's Guide about brown-out-reset.

0 abhishek Sabnis over 13 years ago in reply to old_cow_yellow

Expert 1730 points

Thanks for immediate reply. I went through document.

If i want to disable this brown out reset how can i configure it? i want micro not to restart when i want to make it die.

0 old_cow_yellow over 13 years ago in reply to abhishek Sabnis

Guru 58965 points

You have to cut off the power. If your external power circuit is not able to cu off the power, the MSP430 cannot help you. If you really mean you want MSP430 to die, that is easy.

0 abhishek Sabnis over 13 years ago in reply to old_cow_yellow

Expert 1730 points

Does it mean, i can not drive MOSFET to cut off external power supply, that i mentioned in my first question.

0 old_cow_yellow over 13 years ago in reply to abhishek Sabnis

Guru 58965 points

You can use MSP430 I/O pins to turn on or turn off MOSFET. But jugging from your questions, the rest of your power circuit is not suitable. I have no idea what your circuit is. Brown-out is just one of the possibilities. It could be that your design is fundamentally wrong.

Are you using a MSP430 I/O pin and a MOSFET to keep the power off instead of turn the power off ?

How do you turn on the power? How do you keep it on? Once it is off, how do you keep it off?

0 abhishek Sabnis over 13 years ago in reply to old_cow_yellow

Expert 1730 points

My application consists of battery charger and inverter circuit. and i am using MSP430 as monitoring device. MSP430 gets power through regulator chip when AC power is present and the same time MSOFET is turned on by MSP430. this is when charger circuit is active. now when inverter is active MSP430 gets power from battery through regulator. According to application at predefined battery voltage MSP turns off the inverter and then MOSFET. This MOSFET in turn drives the circuit associated with battery to disconnect the battery. Since battery is disconnected MSP should go to permanent sleep until AC supply is back.

but it appears to be after driving MOSFET low MSP restarts and again sleeps and this happens periodically.

I guess i explained to as much i can. I will check my circuit to make sure nothing is wrong fundamentally.

Thanks for being helpful

0 old_cow_yellow over 13 years ago in reply to abhishek Sabnis

Guru 58965 points

When there is no power to the MSP430, it cannot do anything. Thus (a) it cannot turn on its own power, and (b) it cannot keep its own power off either.

If the MOSFET is controlled by by the MSP430 to keep the MSP430 power off, the moment the MSP430 is turned off, it will be turned back on again because MSP430 can no longer keep it off. This is what I called fundamentally wrong.

When you turn off the power to MSP430, it does not die. It is just not capable of doing anything. When power is restored, it will reset and start to do what it is programmed to do.

0 abhishek Sabnis over 13 years ago in reply to old_cow_yellow

Expert 1730 points

Thanks,

I checked back everyting, i was wrong fundamently in software.

Now everyting is working as inteded.

0 Jens-Michael Gross over 13 years ago

Guru 227245 points

Even though one would think otherwise at first, the MSP canntot 'drive' something low without having power applied. The output driver requires a supply voltage to drive the pin low. So when voltage fails, the MSP won't drive the MSOFET down anymore and remaining charge will leak into the pin, which in turn lets supply voltage come up again.

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MSP430 restarting.....