Add functions to work with a 74HC595 shift register

shift_register/reg.c

@@ -0,0 +1,27 @@
+#include <base.h>
+#include <reg.h>
+
+void shift_register_initialize(shift_register_t *reg) {
+    set_line_direction(&reg->output, LINE_OUT);
+    set_line_direction(&reg->shift_clock, LINE_OUT);
+    set_line_direction(&reg->latch_clock, LINE_OUT);
+
+    clear_line(&reg->output);
+    clear_line(&reg->shift_clock);
+    clear_line(&reg->latch_clock);
+}
+
+void send_byte_lsb(shift_register_t *reg, uint8_t byte) {
+    for (uint8_t i = 0; i < 8; i++) {
+        byte & _BV(i) ? set_line(&reg->output) : clear_line(&reg->output);
+        strobe_line(&reg->shift_clock);
+    }
+}
+
+void shift_out(shift_register_t *reg, uint8_t byte) {
+    send_byte_lsb(reg, byte);
+    clear_line(&reg->output);
+    strobe_line(&reg->latch_clock);
+}
+
+

shift_register/reg.h

@@ -0,0 +1,15 @@
+
+#ifndef __REG_H__
+#define __REG_H__
+
+typedef struct SHIFT_REGISTER {
+    gpio_t output;
+    gpio_t shift_clock;
+    gpio_t latch_clock;
+} shift_register_t;
+
+
+void shift_register_initialize(shift_register_t *reg);
+void shift_out(shift_register_t *reg, uint8_t byte);
+
+#endif