write/verify scratchpad. proper formatting. warning comment.

3 files changed, 125 insertions, 9 deletions

diff --git a/avr/1wire.c b/avr/1wire.c
index affd80d..54c8dcc 100644
--- a/avr/1wire.c
+++ b/avr/1wire.c
@@ -6,6 +6,30 @@
 /*                      danni@specs.de                                  */
 /*                                                                      */
 /************************************************************************/
+
+/* modified by Florian Jung (flo@windfisch.org).
+ * Changelog:
+ *     - try to drive parasite-powered devices via avr-builtin pullup
+ *     - DS199X access functions
+ */
+
+/* WARNING WARNING WARNING:
+ * this code VIOLATES THE 1-WIRE SPECIFICATION! Instead of "letting the
+ * line float" (which implies that it's gently pulled up to 5V by the
+ * pullup resistor), we're hard connecting the line against +5V, without
+ * any resistor in between. After some time, we let the line float, only
+ * held up by the (weak) AVR-internal pullup.
+ *
+ * THIS COULD DESTROY YOUR HARDWARE! you have been warned.
+ *
+ * (We do this because the internal pullup isn't strong enough to serve
+ * the DS1992 with power. The line is only hard-connected to +5V, when
+ * we're (sort of) sure that the DS1992 won't pull down the line to GND
+ * (since that would cause a short-circuit). Buuuut there's no guarantee,
+ * it just works[tm])
+ */
+
+
 #include <util/delay.h>
 #include <avr/io.h>
 #include <avr/interrupt.h>
@@ -176,6 +200,45 @@ void ds1992_read(uint16_t addr, uint8_t* buf, uint8_t len)
 		buf[i] = w1_byte_rd();
 }
 
+void ds1992_scratch_write(uint16_t addr, const uint8_t* buf, uint8_t len)
+{
+	w1_byte_wr(SKIP_ROM);
+	w1_byte_wr(0x0F); // write scratchpad
+	w1_byte_wr((addr & 0x00FF));
+	w1_byte_wr((addr & 0xFF00) >> 8);
+	for (int i=0; i < len; i++)
+		w1_byte_wr(buf[i]);
+}
+
+uint8_t ds1992_scratch_verify(uint16_t addr, const uint8_t* buf, uint8_t len, uint8_t* es_reg_ptr)
+{
+	uint8_t status = 0;
+
+	w1_byte_wr(SKIP_ROM);
+	w1_byte_wr(0xAA); // read scratchpad
+	
+	// check address bytes
+	if (w1_byte_rd() != (addr & 0x00FF)) status |= 0x01;
+	if (w1_byte_rd() != (addr & 0xFF00) >> 8) status |= 0x02;
+	
+	uint8_t es_reg = w1_byte_rd();
+	*es_reg_ptr = es_reg;
+	// check E/S register
+	if (es_reg & 0x20) // PF: partial byte flag
+		status |= 0x04;
+	if (es_reg & 0x40) // OF: overflow flag
+		status |= 0x08;
+	if ((es_reg & 0x1F) != (addr & 0x1F) + (len-1))
+		status |= 0x10;
+
+	for (int i=0; i < len; i++)
+		if (w1_byte_rd() != buf[i])
+			status |= 0xF0;
+	
+	return status;
+}
+
+
 void w1_command( uint8_t command, uint8_t *id )
 {
 	uint8_t i;
diff --git a/avr/1wire.h b/avr/1wire.h
index accb132..af48d0b 100644
--- a/avr/1wire.h
+++ b/avr/1wire.h
@@ -24,4 +24,8 @@ uint8_t w1_byte_rd( void );
 uint8_t w1_rom_search( uint8_t diff, uint8_t*id );
 
 void w1_command( uint8_t command, uint8_t *id );
+
+void ds1992_read(uint16_t addr, uint8_t* buf, uint8_t len);
+void ds1992_scratch_write(uint16_t addr, const uint8_t* buf, uint8_t len);
+uint8_t ds1992_scratch_verify(uint16_t addr, const uint8_t* buf, uint8_t len, uint8_t* es_reg_ptr);
 #endif
diff --git a/avr/main.c b/avr/main.c
index 6774d6e..15d98d3 100644
--- a/avr/main.c
+++ b/avr/main.c
@@ -55,6 +55,8 @@ void jump_to_bootloader(void)
 }
 
 static uchar replyBuffer[130]="Hello world initial";
+static uchar buf[33];
+
 usbMsgLen_t usbFunctionSetup(uchar data[8])
 {
 	usbRequest_t *rq = (void *) data;
@@ -152,28 +154,75 @@ int main(void)
 
 	sei();						// Enable interrupts after re-enumeration
 
+	uint8_t error = 0;
 	while (1)
 	{
 		wdt_reset();			// keep the watchdog happy
 		usbPoll();
 
-		if (++c % (got_data ? 1000 : 3000) == 0)
+		if (++c % (error ? 12000 : got_data ? 1000 : 3000) == 0)
 		{
 			PORTC^=LED_BLUE;
 			PORTC |= LED_RED | LED_GREEN;
 		}
 		if (c % 12000 == 0)
 		{
-			uint8_t result = w1_reset();
-			if (result == 0) // device detected
+			if (!got_data) // we want to read the token
+			{
+				uint8_t result = w1_reset();
+				if (result == 0) // device detected
+				{
+					PORTC &= ~LED_GREEN;
+					ds1992_read(0, replyBuffer, 128);
+				}
+				else if (result == 1) // no presence pulse == no device detected
+					PORTC &= ~LED_RED;
+				else // short circuit detected
+					PORTC &= ~(LED_RED | LED_GREEN);
+			}
+			else // we want to WRITE the token (*shudder*!)
 			{
-				PORTC &= ~LED_GREEN;
-				ds1992_read(0, replyBuffer, 128);
+				uint8_t result = w1_reset();
+				if (result == 0) // device detected
+				{
+					PORTC &= ~LED_GREEN;
+					
+					cli();
+					memcpy(buf, replyBuffer, 33);
+					got_data = 0;
+					sei();
+
+					uint16_t writepos = ((uint16_t)buf[32]) * 32;
+					ds1992_scratch_write(writepos, buf, 32);
+
+					result = w1_reset();
+					if (result != 0)
+					{
+						replyBuffer[0] = 0x01;
+						error = 1;
+						goto write_failed;
+					}
+
+					uint8_t es_reg;
+					result = ds1992_scratch_verify(writepos, buf, 32, &es_reg);
+					if (result != 0)
+					{
+						replyBuffer[0] = 0x02;
+						error = 1;
+						goto write_failed;
+					}
+
+					replyBuffer[0] = 0xFF; // success
+					error = 0;
+
+					write_failed:
+					1;
+				}
+				else if (result == 1) // no presence pulse == no device detected
+					PORTC &= ~LED_RED;
+				else // short circuit detected
+					PORTC &= ~(LED_RED | LED_GREEN);
 			}
-			else if (result == 1) // no presence pulse == no device detected
-				PORTC &= ~LED_RED;
-			else // short circuit detected
-				PORTC &= ~(LED_RED | LED_GREEN);
 
 		}
 	}