new send (works), receive (not tested)

1 files changed, 134 insertions, 62 deletions

diff --git a/main.c b/main.c
index 481757b..f812e4e 100644
--- a/main.c
+++ b/main.c
@@ -1,6 +1,128 @@
 #include <avr/io.h>
 #include <avr/delay.h>
- 
+
+static char buffer[300];
+
+#define OUT0 "sbi %0, 5 \n"  /* pull line to GND */
+#define OUT1 "cbi %0, 5 \n"  /* tristate the line */
+
+#define WAIT10 "ldi r16, 1 \n rcall delay_loop \n"
+#define WAIT34 "ldi r16, 9 \n rcall delay_loop \n"
+#define WAIT10MINUS10 ""
+#define WAIT34MINUS10 "ldi r16,5 \n rcall delay_loop \n nop \n nop \n"
+
+int recv_gc()
+{
+	char* buf_ptr = buffer;
+
+	asm volatile(
+		"recv_wait_low_initial_loop: \n"
+		"sbic %1, 5 \n"
+		"rjmp recv_wait_low_initial_loop \n" // from low to the start of counting: 6 cycles = 0.5us
+		"nop \n"
+		"nop \n"
+		"nop \n"
+		"nop \n"
+
+
+		"recv_loop: \n"
+		"recv_low_begin: \n"
+		"ldi r16, 128 \n" // 1
+		"recv_low_loop: \n"
+		"inc r16 \n"      // 1
+		"breq timeout \n" // 1 if no timeout
+		"sbis %1, 5 \n"   // 1               // von high auf dec: 6
+		"rjmp recv_low_loop \n\n" // 2 if executed, 1 if skipped.
+		"nop \n"          // to account for the rjmp recv_loop below.
+		"nop \n"
+		"nop \n"
+		"nop \n"
+
+		"recv_high_begin: \n"
+		"nop \n" // to account for the ldi in recv_low_begin.
+		"recv_high_loop: \n"
+		"dec r16 \n" // 1
+		"breq timeout \n" // 1 if no timeout
+		"sbic %1, 5 \n" // 1                 // von low auf inc: 6
+		"rjmp recv_high_loop \n\n" // 2 if executed, 1 if skipped
+
+		"st z+, r16 \n" // 2
+		"rjmp recv_loop \n\n" // 2
+
+		"timeout: \n"
+
+		:       "+z" ((unsigned char volatile*) buf_ptr)
+		:	"I" (_SFR_IO_ADDR(PINC))
+		: "r16", "memory"
+		);
+
+		return buf_ptr-buffer;
+
+		// a value of >=128 means "0", <127 means "1" bit.
+}
+
+void send_gc(char* bytes, int len)
+{
+	int k=0;
+	for (int i=0; i<len; i++)
+		for (int j=0x80; j!=0; j=j>>1, k++)
+			buffer[k] = ((bytes[i] & j)!=0)?1:0 ;
+	
+	len=len*8+1;
+	
+	asm volatile(
+		"push r31 \n"
+		"push r30 \n\n"
+
+		"send_loop:   \n"
+		"sbiw %2, 1 \n" // 2
+		"breq send_done \n" // 1 if not done, 2 if done
+		"ld r16, z+ \n" // 2
+		"tst r16 \n" // 1
+		"brne send_one \n\n" // 1 if zero, 2 if nonzero
+
+		"; otherwise, send zero \n"
+		"nop \n" // 1
+		OUT0
+		WAIT34
+		OUT1
+		WAIT10MINUS10
+		"rjmp send_loop \n\n" // 2
+
+		"send_one: \n"
+		OUT0
+		WAIT10
+		OUT1
+		WAIT34MINUS10
+		"rjmp send_loop \n\n"
+
+		"delay_loop:\n"
+		"; this costs 7 + 3*(r16) cycles \n"
+		"dec r16\n"
+		"brne delay_loop\n"
+		"ret\n\n"
+
+		"send_done: \n"
+		"; now send the stop bit and release the line \n"
+		"nop \n nop \n nop \n"
+		OUT0
+		WAIT10
+		OUT1
+		"; done :) \n"
+		"pop r30 \n"
+		"pop r31 \n"
+		
+		: 
+		:	"I" (_SFR_IO_ADDR(DDRC)), 
+			"I" (_SFR_IO_ADDR(PINC)),
+			"w" (len),
+			"z" ((unsigned char volatile*) buffer)
+		: "r16"
+		);
+
+}
+
+
 int main (void)
 {
 	DDRC=0x00;
@@ -9,73 +131,23 @@ int main (void)
 	DDRB=0xFF;
 	PORTB=0x55;
 
-#define OUT0 "sbi %0, 5 \n"  /* pull line to GND */
-#define OUT1 "cbi %0, 5 \n"  /* tristate the line */
-#define NOP "nop \n"
-#define NOP10 NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP
-#define NOP12 NOP10 NOP NOP
 
-#define WAIT10 "ldi r16, 1 \n rcall loop \n"
-#define WAIT34 "ldi r16, 9 \n rcall loop \n"
+	PORTB=0x55;
+
+	int temp=0;
 
-//#define BIT0 OUT0 NOP10 NOP12 NOP12 OUT1 NOP10
-//#define BIT1 OUT0 NOP10 OUT1 NOP10 NOP12 NOP12
 
-#define BIT0 OUT0 WAIT34 OUT1 WAIT10
-#define BIT1 OUT0 WAIT10 OUT1 WAIT34
+       while(1)
+       {
+               temp++;
+//               PORTB=~(1 << ((temp>>9)%6));
+PORTB=~temp;
+               _delay_ms(1);
 
-	PORTB=0x55;
+	char foo[] = { 0x40, 0x03, 0x02 };
 
-	int temp=0;
+	send_gc(foo, 3);
 
-	while(1)
-	{
-		temp++;
-		PORTB=~(1 << ((temp>>9)%6));
-		_delay_ms(1);
-		asm volatile(
-		BIT0
-		BIT1
-		BIT0
-		BIT0
-
-		BIT0
-		BIT0
-		BIT0
-		BIT0
-
-		BIT0
-		BIT0
-		BIT0
-		BIT0
-
-		BIT0
-		BIT0
-		BIT1
-		BIT1
-
-		BIT0
-		BIT0
-		BIT0
-		BIT0
-
-		BIT0
-		BIT0
-		BIT1
-		BIT0
-
-
-		BIT1
-		"rjmp done \n"
-		"loop:\n"
-		"dec r16\n"
-		"brne loop\n"
-		"ret\n"
-		"done: \n"
-		: 
-		: "I" (_SFR_IO_ADDR(DDRC)),  "I" (_SFR_IO_ADDR(PINC)) 
-		: "r16"
-		);
 	}