Library for working with buttons on the MSP430. Example code included in main.c.

Assumes buttons are active low. Configures with internal pull-up resistor if button open state is floating.

• void configureP1PinAsButton(char pin)
  • Configures pin as input with internal pull-up resistor
  • Pin settings
    • P1DIR = 0 (input)
    • P1REN = 1 (enable internal pull-up/pull-down networks)
    • P1OUT = 1 (configure as pull-up)
  • Usage:
    • configureP1PinAsButton(BIT3);
      • Configures Port 1, Pin 3 as button
    • configureP1PinAsButton(BIT0|BIT1|BIT2);
      • Configures Port 1, Pins 0, 1, and 2 as button
• char isP1ButtonReleased(char pin)
  • Returns one if pin is high, zero if pin is low
  • Usage:
    • isP1ButtonReleased(BIT3);
      • Returns 1 if released
      • Returns 0 if pressed
• void waitForP1ButtonRelease(char pin)
  • Blocks until detects pin going high
  • Debounces after detection
  • Usage:
    • waitForP1ButtonRelease(BIT3);
      • Blocks until pin 3 is high, debounces
• char isP1ButtonPressed(char pin)
  • Returns one if pin is low, zero if pin is high.
  • Usage:
    • isP1ButtonPressed(BIT3);
      • Returns 1 if pressed
      • Returns 0 if released
• char pollP1Buttons(char buttonsToPoll[], char numberOfButtonsToPoll)
  • Blocks until button is pushed, returns bit mask of pressed button
  • Usage:
    • Blocks until one of buttons is pushed
    • pressedButton is set to mask of pushed button

char buttons[] = {BIT1, BIT2, BIT3};
char pressedButton = pollP1Buttons(buttons, 3);

• char checkP1Buttons(char buttonsToCheck[], char numberOfButtonsToCheck);
  • Checks set of buttons for press, returns bit mask of pressed button
  • Do this if you don't want to block
• void debounce()
  • Delays for 1000 clock cycles.
  • Time length depends on clock speed, but 1ms with 1MHz clock.
  • Usage:
    • debounce();

Anyone is free to use and modify this for any purpose, provided they document it.