MSP430G2230: Is a capacitor required on RST pin

Jerry Bucci

Part Number: MSP430G2230

Hi,

I'm developing a very low cost, low component count product based on a MSP430G2230. Is the usual cap required on the RST pin. for proper power up. I know the answer is in the 700 Page users manual, but I couldnt find it easily, so I thought it would be easier to just ask.

Thanks,

Jerry

3 months ago

0 Keith Barkley 3 months ago

Guru 43785 points

It is not *required* but bad things can happen if the device goes out of reset while the power is not steady and at the proper level. I would say it is *strongly* recommended.

0 Jerry Bucci 3 months ago

Expert 1550 points

Keith

Thanks for the reply. I should add that i'll be using the onboard clock, and also, the power supply around 2 volts is a simple Zener and capacitor filter of a half wave 60hz AC/DC sine wave. So there will be some 60Hz ripple. This is for cost reasons. The periphorals used will be very slow(temperature) A/D and it will just control some LED's on and off. I will use the watch dog timer, and if it resets the program at any time it will not be a problem as long as it doesnt hang up.

0 Owen Li 3 months ago in reply to Jerry Bucci

TI__Expert 8791 points

Hi Jerry,

As Keith had mentioned, the capacitor on the RST pin is strongly recommended for noise immunity.

Best,

Owen

0 Jerry Bucci 3 months ago in reply to Owen Li

Expert 1550 points

Owen,

Is a 47K pullup also recommended? Is there no internal pullup?

Thanks

Jerry

0 David Schultz 3 months ago in reply to Jerry Bucci

Guru 26235 points

See Table 2-3, Connection of Unused Pins, in the guide.

0 Owen Li 3 months ago in reply to Jerry Bucci

TI__Expert 8791 points

Hi Jerry,

The 47kOhm pull up is recommended. There is no internal pull up and the external pull up is necessary for proper functionality.

Best,

Owen

0 Jerry Bucci 3 months ago in reply to Owen Li

Expert 1550 points

Thanks David & Owen,

Okay. It's interesting that after about 60 years of basically requiring the same RC reset configuration on almost all processors, there must be a good reason why you don't just put an internal pullup to save a component. I do have room for it using 0204 components.

Cheers

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MSP430G2230: Is a capacitor required on RST pin