68 lines
1.6 KiB
C
68 lines
1.6 KiB
C
|
/*
|
||
|
|
* shift.c
|
||
|
|
*
|
||
|
|
* Copyright 2011-2012 Mika Tuupola
|
||
|
|
*
|
||
|
|
* Licensed under the MIT license:
|
||
|
|
* http://www.opensource.org/licenses/mit-license.php
|
||
|
|
*
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "pins/digital.h"
|
||
|
|
#include "shift/shift.h"
|
||
|
|
|
||
|
|
/* Assumes MSB first. */
|
||
|
|
uint8_t shift_in(void) {
|
||
|
|
uint8_t byte = 0;
|
||
|
|
uint8_t pin_value;
|
||
|
|
|
||
|
|
for(int i=0; i<8; i++) {
|
||
|
|
pin_value = digital_read(SHIFT_IN_DATA);
|
||
|
|
byte |= (pin_value << ((8 - 1) - i));
|
||
|
|
/* printf("%d = %d \n", ((8 - 1) - i), pin_value); */
|
||
|
|
|
||
|
|
/* Pulse clock to write next bit. */
|
||
|
|
digital_write(SHIFT_IN_CLOCK, LOW);
|
||
|
|
digital_write(SHIFT_IN_CLOCK, HIGH);
|
||
|
|
}
|
||
|
|
return byte;
|
||
|
|
}
|
||
|
|
|
||
|
|
void shift_in_latch(void) {
|
||
|
|
digital_write(SHIFT_IN_LATCH, LOW);
|
||
|
|
digital_write(SHIFT_IN_LATCH, HIGH);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
void shift_in_init(void) {
|
||
|
|
pin_mode(SHIFT_OUT_LATCH, OUTPUT);
|
||
|
|
pin_mode(SHIFT_OUT_CLOCK, OUTPUT);
|
||
|
|
pin_mode(SHIFT_OUT_DATA, INPUT);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Assumes MSB first. */
|
||
|
|
void shift_out(uint8_t data) {
|
||
|
|
for(uint8_t i = 0; i < 8; i++) {
|
||
|
|
/* Write bit to data port. */
|
||
|
|
if (0 == (data & _BV(7 - i))) {
|
||
|
|
digital_write(SHIFT_OUT_DATA, LOW);
|
||
|
|
} else {
|
||
|
|
digital_write(SHIFT_OUT_DATA, HIGH);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Pulse clock to write next bit. */
|
||
|
|
digital_write(SHIFT_OUT_CLOCK, LOW);
|
||
|
|
digital_write(SHIFT_OUT_CLOCK, HIGH);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void shift_out_latch(void) {
|
||
|
|
digital_write(SHIFT_OUT_LATCH, LOW);
|
||
|
|
digital_write(SHIFT_OUT_LATCH, HIGH);
|
||
|
|
}
|
||
|
|
|
||
|
|
void shift_out_init(void) {
|
||
|
|
pin_mode(SHIFT_OUT_LATCH, OUTPUT);
|
||
|
|
pin_mode(SHIFT_OUT_CLOCK, OUTPUT);
|
||
|
|
pin_mode(SHIFT_OUT_DATA, OUTPUT);
|
||
|
|
}
|