High impedance inputs of I/O pins in MSP430

Alexei Arkhangelsky

Hi to all,

I am working with Evaluation Module incorporates an intelligent peripheral,
which is controlled via SPI by onboard MSP430 processor.

Sometimes I need to keep the MSPs I/O pins inactive (to make all I/Os are high.impedance inputs) awhile,
and manage onboard peripheral via program SPI by other means.

Could I do this using low level Reset pin on MSP430?
If it' possible, how long could I keep a low level Reset?

Thanks in advance!

Alexei

over 12 years ago

0 Jens-Michael Gross over 12 years ago

Guru 227245 points

Well, pulling RST low will set all port pins to high impedance inputs. And you can keep RST low for any duration.

But if you just need the MSP to not use SPI, you can use multi-master mdoe (4-wire SPI) or just signal with an I/O pin that the MSP is not in charge to control the peripherals yet. Keep in mind that pulling RST low will result in a cold-start when RST is released. Which isn't always suitable.

0 Maximilian Kostka over 12 years ago

Prodigy 190 points

Alexei Arkhangelsky said:
Sometimes I need to keep the MSPs I/O pins inactive

If you want not-active Pins I would suggest to set the Pins Output and low (as recommenden in the User's Guide)

P1OUT = 0x0;

P1DIR = 0xF;

This should avoid any troubles of floating.

Max

0 Alexei Arkhangelsky over 12 years ago in reply to Jens-Michael Gross

Prodigy 30 points

Thanks a lot, Jens-Michael for your unswer.

Kind regards,

Alexei

0 Alexei Arkhangelsky over 12 years ago in reply to Maximilian Kostka

Prodigy 30 points

Max, thanks for your answer.

Kind regards,

Alexei

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High impedance inputs of I/O pins in MSP430