MSP430F2274 TO 4 DIGIT 7 SEGMENT LED DISPLAY

By the way, my current codings are


#include "msp430x22x4.h"

int main( void )
{
 
  WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer to prevent time out reset
  P2DIR |=0x01; //Set P2.0 to output direction
  P2DIR |=0x02; //Set P2.1 to output direction 
  P2DIR |=0x04; //Set P2.2 to output direction
  P2DIR |=0x08; //Set P2.3 to output direction
  P2DIR |=0x10; //Set P2.4 to output direction
  P4DIR |=0x04; //Set P4.3 to output direction
 
  P2OUT =0x08;
  P4OUT =0x00;
   
 
}

You down't write much abotu your hardware. From what I understand, you have a 4-digit 7 segment display. Well...

Does it have 1 HEX-to-7segment decoder internally or do you need to access the segments individually? Is the multiplexing done with 4 independent common cathode/anode signals or doe sit have a multiplex input?

In the most common case, you'll have 4 separate 7-segment displays with 7 individual cathodes (or anodes) wired together across the 4 displays, and one separate anode (or cathode) for each display.

This means you'll need 11 port signals on the MSP. You code has only 6.

sean yee said:

  P2DIR |=0x01; //Set P2.0 to output direction
  P2DIR |=0x02; //Set P2.1 to output direction 
  P2DIR |=0x04; //Set P2.2 to output direction
  P2DIR |=0x08; //Set P2.3 to output direction
  P2DIR |=0x10; //Set P2.4 to output direction

However, for a 7 segment display, you'll need 7 pins for the data and 4 pins for the multiplex.

Let's assume P2.0 to P2.6 are for the data and P4.0 to P4.3 are for the multiplexing.

Port Initialization would be:

P2OUT=0x7F;
P4OUT=0x00;
P2DIR = 0x7F;
P4DIR = 0x00;

Then set up the timer.

TA0CTL = TASSEL_2|MC_1|TACLR;
TA0CCTL0 = CCIE;
TA0CCR0 = 9999;

Assuming a default clock speed of 1MHz (you might need to configure the clock module to get a known clock frequency), this will result in one CCR0 interrupt every 10 ms, so the switching frequency is 100Hz and the display turnaround frequency is 25Hz. A smaller TA0CCR0 value increases the frequency.

Inside the ISR (TIMERA0_VECTOR) you need to put the following:

static unsigned char digit = 0;
P4OUT = 0; // disable the display
P2OUT = value[digit]; // set the (precalculated) bit combination of the 7 segments for this digit from a (global) array
P4OUT = 1<<digit;
digit++;
if(digit==4)digit=0;

Of course you'll need to put useful data into a global array 'unsigned char value[4]'.

That's all.

ok bro, i have a CD4555b decoder and im using CD4511 ic chip to control the 7 Segments so yeap