Question

Lab 3 - Branching, Push Button and LEDs-Reading Assignment in this lab, we are going to control a LED via a push button- using general purpose digital 10 for both input (button) and output (LED) on port 1 - using Code Composer Studio. Furthermore, we are going to use a branch instruction to create an IF-ELSE structure in assembly to determine if the LED should be lit up based on the state of the button. A jump instruction will be implemented as an endless loop (a WHILE structure). Tutorial and Background several Port 1 registers: General Purpose /O (Input/Output) using port 1 can be implemented by controlling and reading P1DIR is a register that controls all 8 pins of the port. If a one is written to any bit, the corresponding pin becomes and output. This means specifically that the output driver has been enabled. This can be dangerous in that if you have the pin tied high or low and the output tries to drive the opposite value, then you effectively have a short in the system and inevitably will see smoke... beware. P1OUT is the resister that determines the value of all pins that are programmed as outputs by P1DIR. For the input bits, this register is meaningless- effectively determining the input value to an output buffer that is disabled P1IN is the register that can be read to see the value of every pin, regardless of whether the pin is defined as input or output. Vilis v so any voltage input below this will be seen as a zero. Vih is 2.4V for 3.3V Vdd. Any voltage in between is undefined P1REN is the register that can program a pull up or pull down resistor internal to the chip. Normally inputs have neither. By writing a one to a bit on a pin defined as an input, the value of P1OUT will determine if there is a pull up (one) or pull down (zero). The push button requires a pull up either on the board or inside the chip. P1SEL is the register that selects which part of the chip is controlling the pin. The reset value is Port 1 so for this lab, no change is required. In later labs, you may need to change this to bring other functionality to the pins of the chip

I need help with doing these tasks for code composer

Answer 1

Answer :- 3)a) The code can be written as-

#include <msp430.h>

vaoid main(void)
{

WDTCTL = WDTPW | WDTHOLD;
P1DIR |= 0x40;
P1REN = 0x01;
P1IN = ~0x08;
P1OUT = 0x40;

while(1)
{
if(P1IN & 0x08) /* if button is pressed */
P1OUT |= 0x04; /* make led on if button is pressed */
else
P1OUT &= ~0x04; /* else make led off */
}

}

Answer :- 3)c) Assuming green LED is at pin 1.5 as it is difficult to find out the poin for green LED from the attached figure.The code can be written as-

#include <msp430.h>

vaoid main(void)
{

WDTCTL = WDTPW | WDTHOLD;
P1DIR |= 0x60; /* making pin6 and pin5 both as output pin by writing 0110_0000 */
P1REN = 0x01;
P1IN = ~0x08;
P1OUT = 0x40; /* initially making red led on and green led off */

while(1)
{
if(P1IN & 0x08) /* if button is pressed */
P1OUT ^= 0x02; /* make green led to blink by toggling each time */
else
P1OUT ^= 0x04; /* else make red led to blink */
}

}

Dear student, to write the code for part b we need processors working frequency so that we can calculate the delay count value. You can write the value in the comment section. Thank you.