Finish making the code for a subtractor in C (with the code on the bottom), and

Question

Finish making the code for a subtractor in C (with the code on the bottom), and make sure it complies with the msp430 microcontroller. Please read all the instructions below in the pictures.

You need to design and implement a digital tester for a full subtractor using an MSP430 Launchpad Analyze and modify the source code of the MSP430F20xx Demo below to produce the subtractor test inputs. A full subtractor performs single-bit subtraction of a minuend minus subtrahend and borrow bits. The latter is borrowed by the next least significant minuend bit in a multiple-bit difference calculation Minuend SubtrahendBorrow Differene Borrow (D) Out (Bo) B Full Subtractor In (Bin) Bo Bin AB AB AB AB AB AB AB1 AB AB1 AB Bin Figure 1. Full subtractor truth table, block diagram, K-maps, and logical circuit

Explanation / Answer

Explanation:

I took 3 pins (0,1,2) of P1 and set them as Output pins. These 3 pins are Input for the full subtractor. In an infinite loop, I generate the values, 000,001,010,011,100,101,110,111 for ABBin according to the truth table.

Code:

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//******************************************************************************
// MSP430F20xx Demo - Software Toggle P1.0
//
// Description; Toggle P1.0 by xor'ing P1.0 inside of a software loop.
// ACLK = n/a, MCLK = SMCLK = default DCO
//
// MSP430F20xx
// -----------------
// /|| XIN|-
// | | |
// --|RST XOUT|-
// | |
// | P1.0|-->LED
//
// M.Buccini / L. Westlund
// Texas Instruments, Inc
// October 2005
// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.40A
//******************************************************************************

#include <msp430.h>

#define A BIT0
#define B BIT1
#define Bin BIT2

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
P1DIR |= A + B + Bin; // Set P1.0 to output direction

for (;;)
{
volatile unsigned int i;

P1OUT = ~(A | B | Bin); // Set output port values according to truth table //000
delay(); // Adding delay

P1OUT = ~(A | B) | Bin; //001
delay();

P1OUT = ~(A | Bin) | B; //010
delay();

P1OUT = ~(A) | (B | Bin); //011
delay();

P1OUT = A | ~(B | Bin); //100
delay();

P1OUT = A | ~B | Bin; //101
delay();

P1OUT = A | B | ~Bin; //110
delay();

P1OUT = A | B | Bin; //111
delay();

}
}

void delay(void)
{
int i = 50000; // Delay
do (i--);
while (i != 0);
}

NOTE: I don't have a board to test but this code compiles on CCSv7. In the function, I have set Bit 0,1,2 as input to subtractor. Please upvote. Thanks.

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