Hi!
I try to use a shift Register. The one i have is a 74HC597 from ti. The examples are all based on the 595 Version that is different.
I found a Tutorial that Shows how to use it with Arduino, but i can not transfer this to the MSP430.
The Thing i read in this tutorial is that there is a fourth pin (PL in the data sheet) that shifts the Information from the middle Register to the shift Register.
The Datasheet itself does not tell me what to do (that means i do not found something that helped me).
Can someone explain what to do?
Here is the original ti sample code with my added LOAD pin, what seems to be wrong but i really dont know how to use ist. Where do i have to pulse the LOAD pin?
//***************************************************************************************
// MSP430 Driver for 74HC595 Shift Register
//
// Description; Drives 8 LED's with 3 digital pins of the MSP430, via a shift register
//
// MSP430x2xx
//
//***************************************************************************************
#include
<msp430g2553.h>
//Define our pins
#define
DATA BIT0 // DS -> 1.0
#define
CLOCK BIT4 // SH_CP -> 1.4
#define
LATCH BIT5 // ST_CP -> 1.5
#define
ENABLE BIT6 // OE -> 1.6
#define
LOAD BIT3 // PL -> 1.3
// The OE pin can be tied directly to ground, but controlling
// it from the MCU lets you turn off the entire array without
// zeroing the register
// Declare functions
void
delay ( unsigned int );
void
pulseClock ( void );
void
shiftOut ( unsigned char );
void
enable ( void );
void
disable ( void );
void
init ( void );
void
pinWrite ( unsigned int, unsigned char );
int
main( void )
{
// Stop watchdog timer to prevent time out reset
WDTCTL = WDTPW + WDTHOLD;
P1DIR |= (DATA + CLOCK + LATCH + ENABLE + LOAD);
// Setup pins as outputs
enable();
// Enable output (pull OE low)
int i;
//Do a "ping-pong" effect back and forth
for(;;){
for ( i = 0 ; i < 8 ; i++ ){
shiftOut(1 << i);
delay(50);
}
for ( i = 7 ; i >= 0 ; i-- ){
shiftOut(1 << i);
delay(50);
}
}
}
// Delays by the specified Milliseconds
// thanks to:
// http://www.threadabort.com/archive/2010/09/05/msp430-delay-function-like-the-arduino.aspx
void
delay(unsigned int ms)
{
while (ms--)
{
__delay_cycles(1000);
// set for 16Mhz change it to 1000 for 1 Mhz
}
}
// Writes a value to the specified bitmask/pin. Use built in defines
// when calling this, as the shiftOut() function does.
// All nonzero values are treated as "high" and zero is "low"
void
pinWrite( unsigned int bit, unsigned char val )
{
if (val){
P1OUT |= bit;
}
else {
P1OUT &= ~bit;
}
}
// Pulse the clock pin
void
pulseClock( void )
{
P1OUT |= CLOCK;
P1OUT ^= CLOCK;
}
// Take the given 8-bit value and shift it out, LSB to MSB
void
shiftOut(unsigned char val)
{
//Set latch to low (should be already)
P1OUT &= ~LATCH;
char i;
// Iterate over each bit, set data pin, and pulse the clock to send it
// to the shift register
for (i = 0; i < 8; i++) {
pinWrite(DATA, (val & (1 << i)));
pulseClock();
}
// Pulse the latch pin to write the values into the storage register
P1OUT |= LATCH;
P1OUT &= ~LATCH;
P1OUT |= LOAD;
P1OUT &= ~LOAD;
}
// These functions are just a shortcut to turn on and off the array of
// LED's when you have the enable pin tied to the MCU. Entirely optional.
void
enable( void )
{
P1OUT &= ~ENABLE;
}
void
disable( void )
{
P1OUT |= ENABLE;
}
Thank You!
Kind Regards, Steffen
