Configuring input on MSP430

microcontrollermsp430

I've been trying to get 2 input push-buttons working on my MSP430 FF529.

I've been successful with 1, but not the other, which leads me to think the one not working is broken, since I'm doing the exact same thing for both.

The two push-buttons on this board are attached to ports P1.1 and P2.1

I got P2.1 to work fine by doing:

P2DIR = 0x00;    //set as input
P2REN |= 0x02;   //enable pullup for p2.1

Now for Port 1, I also need an LED attached to P1.0 as output, so I have done:

P1DIR = 0x01;  //set p1.0 as output, and p1.1 as input
P1REN |= 0x02; //enable pullup for p1.1

So P2.1 is working perfectly fine. The default value is HIGH, and I can see it switch to LOW when I press the button. But this is not the case for P1.1. The default value for this is LOW, and pressing the button has no effect. Am I missing something obvious? Or something different about this port than the other port?

The parts I'm referring to are in green boxes.

MSP430 FF529

enter image description here

Best Answer

As OP has noted in the comments, issue was due to code changing the state of the Port 1 Output P1OUT. When PxREN is enabled for a given port and pin, the corresponding bit for the same port and pin in PxOUT controls whether the builtin Pull-Up (Logic 1) or Pull-Down (Logic 0) is connected. PxDIR must also be set to Logic 0 for the port and pin to be an input.

Consequently, Op had set the P1.1 Button Input to pull-down to Gnd, when the button is also tied to Gnd when pressed.

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Electronic – reading voltage using TI’s MSP430 FF22x4

This is the code that worked:

ADC10CTL1 = INCH_1 + CONSEQ_0;
ADC10CTL0 = SREF_1 + ADC10SHT_2 + REFON + ADC10ON + ADC10IE;
for (countDown = 240; countDown > 0; countDown--); //delay to allow references to settle
ADC10AE0 |= 0x02;
ADC10CTL0 |= ENC + ADC10SC; //Sampling and conversion start
__bis_SR_register(CPUOFF + GIE);        // LPM0 with interrupts enabled
result = ADC10MEM; //result is a int
incomingVoltage[0] = result&0xFF; //incoming voltage is an array of uint8_t, send it to AP
incomingVoltage[1] = (result>>8)&0xFF; //this and previous line is similar to temperature sensing code sample

Thanks for the help!

Electronic – Making PWM from 2 Analog input in MSP430G2231

You are not waiting for the ADC to finish the conversions. You would have to do something like this:

 for (;;)
{
  ADC10CTL0 &= ~ENC;

  while (ADC10CTL1 & BUSY);                 // Wait if ADC10 core is active
    ADC10SA = 0x200;                        // Data buffer start
    P1OUT |= 0x01;                          // Set P1.0 LED on
    ADC10CTL0 |= ENC + ADC10SC;             // Sampling and conversion start
    __bis_SR_register(CPUOFF + GIE);        // LPM0, ADC10_ISR will force exit
    P1OUT &= ~0x01;                         // Clear P1.0 LED off
 }

}

You should read the user guide - chapter 20 (I think) ADC10 and look at the code examples on ADC10 with DTC

Best Answer

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Electronic – reading voltage using TI’s MSP430 FF22x4

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