Question

Using MSP430xxx Microcontroller, write a C program to count the number of times the button is pressed and show the current value on the LEDs. Of course, this works better on a demonstration board with more LEDs. You should set the pins for both LEDs to outputs and turn the LEDs off initially. The statement P2OUT -= LED1 causes the displayed value to be incremented by 1 . Why does this work? (It would be clearer if the LEDs were active high and connected to bits 0 upward.) This is a reminder of memory-mapped input and output: you can do arithmetic on the output register P2OUT as if it were a simple location in RAM.

Answer 1

A C program on an MSP430 microcontroller to track button presses and display the count on LEDs uses memory-mapped I/O registers and bitwise operations to update LED states. The use of operations such as P2OUT -= LED1 assumes LEDs are active low. The program must include button debouncing for accurate count.

Step-by-step explanation:

Writing a C program for the MSP430 microcontroller to count button presses and display the count value on LEDs involves configuring I/O pins, setting up an interrupt for the button press, and coding a mechanism to update the LED display. The MSP430's peripheral registers, like P2OUT, are memory-mapped, which allows for direct manipulation of I/O pin states in a similar fashion to regular RAM operations. When the statement P2OUT -= LED1 is executed, it effectively toggles the state of the LED connected to the pin that LED1 represents, assuming LED1 is a bitmask with a single bit set corresponding to the LED's pin. This works under the assumption that the LEDs connected to Port 2 are active low, which means they are illuminated when the output is driven low.

In an active high configuration, one might expect to see code like P2OUT |= LED1 to turn on an LED and P2OUT &= ~LED1 to turn it off. For incrementing the displayed value on the LEDs, each button press would typically result in a bitwise operation that modifies the P2OUT register to reflect the new count, lighting the appropriate LEDs to represent the current count in binary. It is essential to debounce the button to ensure accurate count increments, preventing false triggering due to the mechanical nature of the button switch.