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Launchpad MSP430G2231 use pin 1. for analog input.

Kjell Holen
Intellectual 260 points

I am new to LP. Testing a code for a scope found at "http://www.msp430launchpad.com/2010/12/njcs-launchscope-launchpad-oscilloscope.html"  It works, but use p1.3 (A3) as input.That pin has a pulldown resistor. (have searched the forum, but found no answer) To use p1.3 as analog input, is the solution to use an op.amp. between p1.3 and the analog signal or are there other pin on the LP that could be used? An opamp can also "clip" the signal when to high or neg.

  • 0
    Guru 227245 points

    All P1 pins, P1.0 to P1,7, can be used as analog input. Of course you have to make the appropriate changes to the P1 registers and also to select the other input (A0 to A7) for the ADC. A3 on the LaunchPad just haspullup and capacitor on it for supply of the pushbutton I don't know why your code used this pin.Of course P1.0 and P1.6 are used for the two LEDs and P1.1 and P1.2 (A1, A2) are used for the backchannel UART and are connected to the Launchpads FET.

    So P1.4, P1.5 and P1.7 (A4, A5, A7) are candidates for undisturbed analog input.

  • 0 in reply to Jens-Michael Gross
    Intellectual 260 points

    Thanks, I will try using one of those pin.

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