Fixed pin definition problems and unified SPI reading and writing.

include/spi.h

 #ifdef DEBUG
 
 // Arduino D3 = PD3
-#define SCK_on PORTD |= PD3
-#define SCK_off PORTD &= ~(PD3)
+#define SCK_on PORTD |= (1 << PD3)
+#define SCK_off PORTD &= ~(1 << PD3)
 #define SCK_dir DDRD |= (1 << PD3)
 
-// Arduino D2 = PD2
-#define MO_on PORTD |= PD2
-#define MO_off PORTD &= ~(PD2)
-#define MO_dir DDRD &= ~(1 << PD2)
+// Arduino D7 = PD7
+#define MO_on PORTD |= (1 << PD7)
+#define MO_off PORTD &= ~(1 << PD7)
+#define MO_dir DDRD |= (1 << PD7)
 
 // Arduino D8 = PB0
-#define CS_on PORTB |= PB0
-#define CS_off PORTB &= ~(PB0)
+#define CS_on PORTB |= (1 << PB0)
+#define CS_off PORTB &= ~(1 << PB0)
 #define CS_dir DDRB |= (1 << PB0)
 
-// Arduino D7 = PD7
-#define MI_1 (PIND & PD7) == PD7
-#define MI_0 (PIND & PD7) != PD7
-#define MI_dir DDRD |= (1 << PD7)
+// Arduino D2 = PD2
+#define MI_1 (PIND & (1 << PD2)) != 0
+#define MI_0 (PIND & (1 << PD2)) == 0
+#define MI_dir DDRD &= ~(1 << PD2); PORTD |= (1 << PD2)
 
 // Arduino D9 = PB1
-#define GDO_1 (PINB & PB1) == PB1
-#define GDO_0 (PINB & PB1) != PB1
-#define GDO_dir DDRB &= ~(1 << PB1)
+#define GDO_1 (PINB & (1 << PB1)) != 0
+#define GDO_0 (PINB & (1 << PB1)) == 0
+#define GDO_dir DDRB &= ~(1 << PB1); PORTB |= (1 << PB1)
 
 #else
 
-#define SCK_on PORTB |= PB4
-#define SCK_off PORTB &= ~(PB4)
+#define SCK_on PORTB |= (1 << PB4)
+#define SCK_off PORTB &= ~(1 << PB4)
 #define SCK_dir DDRB |= (1 << PB4)
 
-#define MO_on PORTB |= PB3
-#define MO_off PORTB &= ~(PB3)
-#define MO_dir DDRB &= ~(1 << PB3)
+#define MO_on PORTB |= (1 << PB2)
+#define MO_off PORTB &= ~(1 << PB2)
+#define MO_dir DDRB |= (1 << PB2)
 
-#define CS_on PORTB |= PB1
-#define CS_off PORTB &= ~(PB1)
+#define CS_on PORTB |= (1 << PB1)
+#define CS_off PORTB &= ~(1 << PB1)
 #define CS_dir DDRB |= (1 << PB1)
 
-#define MI_1 (PINB & PB2) == PB2
-#define MI_0 (PINB & PB2) != PB2
-#define MI_dir DDRB |= (1 << PB2)
+#define MI_1 (PINB & (1 << PB3)) != 0
+#define MI_0 (PINB & (1 << PB3)) == 0
+#define MI_dir DDRB &= ~(1 << PB3); PORTB |= (1 << PB3)
 
-#define GDO_1 (PINB & PB0) == PB0
-#define GDO_0 (PINB & PB0) != PB0
-#define GDO_dir DDRB &= ~(1 << PB0)
+#define GDO_1 (PINB & (1 << PB0)) != 0
+#define GDO_0 (PINB & (1 << PB0)) == 0
+#define GDO_dir DDRB &= ~(1 << PB0); PORTB |= (1 << PB0)
 
 #endif
 
 #define NOP() __asm__ __volatile__("nop")
 
 void spiInit(void);
-void spiWrite(uint8_t command);
-uint8_t spiRead(void);
+uint8_t spiReadWrite(uint8_t command);
+
+#define spiWrite(x) spiReadWrite(x)
+#define spiRead() spiReadWrite(0)
 
 #endif
 

src/spi.c

     MO_dir;
     SCK_dir;
     CS_dir;
-    GDO_dir;
 
     SCK_off;
     MO_off;
     CS_on;
 }
 
-void spiWrite(uint8_t command) {
+uint8_t spiReadWrite(uint8_t command) {
     SCK_off;
     MO_off;
 
-    uint8_t n = 8;
-    while (n--) {
+    uint8_t result = 0;
+    for (uint8_t i = 0; i < 8; i++) {
         if (command & 0x80) {
             MO_on;
         } else {
             MO_off;
         }
-
-        SCK_on;
-        NOP();
-        SCK_off;
-
         command = command << 1;
-    }
-
-    MO_on;
-}
-
-uint8_t spiRead(void) {
-    uint8_t result = 0;
 
-    for (uint8_t i = 0; i < 8; i++) {
         if (MI_1) {
             result = (result << 1) | 0x01;
         } else {
 
         SCK_on;
         NOP();
+
+#ifdef DEBUG
+        NOP();
+        NOP();
+        NOP();
+        NOP();
+#endif
+
         SCK_off;
         NOP();
+
+#ifdef DEBUG
+        NOP();
+        NOP();
+        NOP();
+        NOP();
+#endif
     }
 
     return result;