Use Triple-A shifting library instead.

tpic6b595_shiftout/Makefile

@@ -51,7 +51,7 @@ FORMAT = ihex
 TARGET = main
 
 # List C source files here. (C dependencies are automatically generated.) 
-SRC = $(TARGET).c uart/uart_async.c 
+SRC = $(TARGET).c uart/uart_async.c shift/shift.c
 
 # List Assembler source files here.
 #     Make them always end in a capital .S.  Files ending in a lowercase .s

tpic6b595_shiftout/main.c

@@ -23,7 +23,7 @@
  * 
  * To compile and upload run: make clean; make; make program;
  * 
- * Copyright 2011 Mika Tuupola
+ * Copyright 2011-2012 Mika Tuupola
  *
  * Licensed under the MIT license:
  *   http://www.opensource.org/licenses/mit-license.php
@@ -36,42 +36,11 @@
 
 #include "main.h"
 #include "uart/uart.h" 
-#include "pins/digital.h"
-
-//#define LATCH   10  /* RCK */
-//#define DATA    11  /* SER IN */
-//#define CLOCK   13  /* SRCK */
-
-#define LATCH   B0  /* RCK */
-#define DATA    B2  /* SER IN */
-#define CLOCK   B1  /* SRCK */
-
-
-static void init(void) {    
-    pin_mode(LATCH, OUTPUT);
-    pin_mode(CLOCK, OUTPUT);
-    pin_mode(DATA,  OUTPUT); 
-}
-
-/* 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(DATA, LOW);            
-        } else {
-            digital_write(DATA, HIGH);
-        }
-        
-        /* Pulse clock input to write next bit. */
-        digital_write(CLOCK, LOW);
-        digital_write(CLOCK, HIGH);
-    }
-}
+#include "shift/shift.h"
 
 int main(void) {    
     
-    init();
+    shift_out_init();
     uart_init();
     stdout = &uart_output;
     stdin  = &uart_input;
@@ -80,8 +49,7 @@ int main(void) {
     /* Show pattern for 5 seconds. */
     shift_out(0b10101010);
     shift_out(0b11110000);
-    digital_write(LATCH, LOW); 
-    digital_write(LATCH, HIGH);
+    shift_out_latch();
     _delay_ms(5000);
     
     while (1) {
@@ -96,9 +64,7 @@ int main(void) {
             shift_out(i & 0xff);
 
             /* Pulse latch to transfer data from shift registers */
-            /* to storage registers (should this be inside shift_out()?). */
-            digital_write(LATCH, LOW); 
-            digital_write(LATCH, HIGH);
+            shift_out_latch();
 
             _delay_ms(50);
         }

tpic6b595_shiftout/main.h

@@ -1,3 +1 @@
-static void init(void);
-void shift_out(uint8_t data);
 int main(void);

tpic6b595_shiftout/shift/shift.c

@@ -0,0 +1,68 @@
+/*
+ * 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);
+}

tpic6b595_shiftout/shift/shift.h

@@ -0,0 +1,30 @@
+/*
+ * shift.h
+ *
+ * Copyright 2011-2012 Mika Tuupola
+ *
+ * Licensed under the MIT license:
+ *   http://www.opensource.org/licenses/mit-license.php
+ *
+ */
+#ifndef SHIFT_H
+#define SHIFT_H
+
+/* Configure ports here. */
+#define SHIFT_IN_LATCH   B0
+#define SHIFT_IN_DATA    B2
+#define SHIFT_IN_CLOCK   B1
+
+#define SHIFT_OUT_LATCH  B0
+#define SHIFT_OUT_DATA   B3
+#define SHIFT_OUT_CLOCK  B1
+
+uint8_t shift_in(void);
+void shift_in_latch(void);
+void shift_in_init(void);
+void shift_out(uint8_t data);
+void shift_out_latch(void);
+void shift_out_init(void);
+
+#endif /* SHIFT_H */
+