Switch back to C based timeout ISR in the AVRISP project - assembly version was failing, and only one or two cycles could be shaved off the compiler generated code.

Projects/AVRISP-MKII/Lib/Timeout.S

@@ -1,23 +0,0 @@
-#include <avr/io.h>
-#include "V2Protocol.h"
-
-.global TIMER0_COMPA_vect
-TIMER0_COMPA_vect:
-	sei
-	push	r24
-	in	r24, 0x3f
-	push	r24
-
-	in	r24, TimeoutMSRemaining
-	and	r24, r24
-	breq	Epilogue
-	subi	r24, 0x01
-	out	TimeoutMSRemaining, r24
-
-Epilogue:
-	pop	r24
-	out	0x3f, r24
-	pop	r24
-	reti	
-	
-	

Projects/AVRISP-MKII/Lib/V2Protocol.c

@@ -43,6 +43,12 @@ uint32_t CurrentAddress;
 bool MustSetAddress;
 
 
+ISR(TIMER0_COMPA_vect, ISR_NOBLOCK)
+{
+	if (TimeoutMSRemaining)
+	  TimeoutMSRemaining--;
+}
+
 /** Initializes the hardware and software associated with the V2 protocol command handling. */
 void V2Protocol_Init(void)
 {

Projects/AVRISP-MKII/Lib/XPROG/XPROGTarget.c

@@ -165,6 +165,10 @@ void XPROGTarget_EnableTargetPDI(void)
 	BITBANG_PDIDATA_DDR  |= BITBANG_PDIDATA_MASK;
 	BITBANG_PDICLOCK_DDR |= BITBANG_PDICLOCK_MASK;
 	
+	/* Set DATA line low for at least 90ns to ensure that the device is ready for PDI mode to be entered */
+	BITBANG_PDIDATA_PORT &= ~BITBANG_PDIDATA_MASK;
+	_delay_us(1);
+
 	/* Set DATA line high for at least 90ns to disable /RESET functionality */
 	BITBANG_PDIDATA_PORT |= BITBANG_PDIDATA_MASK;
 	_delay_us(1);
@@ -314,6 +318,9 @@ void XPROGTarget_SendByte(const uint8_t Byte)
 	SoftUSART_Data     = NewUSARTData;
 	SoftUSART_BitCount = BITS_IN_USART_FRAME;
 #endif
+
+    if (TimeoutMSRemaining)
+	  TimeoutMSRemaining = COMMAND_TIMEOUT_MS;
 }
 
 /** Receives a byte via the software USART, blocking until data is received.
@@ -369,6 +376,9 @@ void XPROGTarget_SendBreak(void)
 	SoftUSART_Data     = 0x0FFF;
 	SoftUSART_BitCount = BITS_IN_USART_FRAME;
 #endif
+
+    if (TimeoutMSRemaining)
+	  TimeoutMSRemaining = COMMAND_TIMEOUT_MS;
 }
 
 static void XPROGTarget_SetTxMode(void)
@@ -405,6 +415,9 @@ static void XPROGTarget_SetTxMode(void)
 	}
 #endif
 
+    if (TimeoutMSRemaining)
+	  TimeoutMSRemaining = COMMAND_TIMEOUT_MS;
+
 	IsSending = true;
 }