MSP430F2132 Open Drain Output

Sputnik

Other Parts Discussed in Thread: MSP430F2132

Hi,

I'm using the MSP430F2132 in an ultrasound distance measurement project.

For the ultrasound detector, there are two op-amp gain stages, the second stage has its gain controlled by setting the gain resistors (R20, R21, R23, R24) high or low.

To control the resistors and allow them to sink current, P1.4, P1.5, P1.6, P1.7 should be set as open-drain as far as i understand.

From what i gather on the forums, the MSP430 does not support open-drain. So question is, can anyone explain how i should set up the pins to achieve this?

Thank you.

over 13 years ago

0 old_cow_yellow over 13 years ago

Guru 58965 points

I think you can set up each pin as either (a) digital output low or (b) digital input without pullup/down. Once you set that up, the difference between the two states is the DIR bit.

OUT=0; REN=0; SEL=0; IE=0; DIR=1 or 0 as desired.

0 Jens-Michael Gross over 13 years ago

Guru 227245 points

Indeed, the MSP does not support open drain for its port pins, but you can simulate open drain by simply putting a schottky diode in series.

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MSP430F2132 Open Drain Output