Initial commit of files

src/libPIC/dly_usec.c

@@ -0,0 +1,113 @@
+/*****************************************************************************
+ * Copyright (C) 2008
+ * ProbeStar Telematics, LLC
+ * All Rights Reserved.  Proprietary and Confidential.
+ *============================================================================
+ * Microsecond Delay Routine using Timer 0
+ *----------------------------------------------------------------------------
+ * 200nsec instruction cycle at 20Mhz, 100nsec at 40Mhz
+ * You have to examine the asm output to count the instructions
+ * Make sure this code is compiled with optimization -O -Zg4
+*****************************************************************************/
+
+/*****************************************************************************
+ * includes
+*****************************************************************************/
+
+#include "system.h"
+#include "delay.h"
+
+/*****************************************************************************
+ * defines
+*****************************************************************************/
+
+/*****************************************************************************
+ * macros
+*****************************************************************************/
+
+/*****************************************************************************
+ * structs & typedefs
+*****************************************************************************/
+
+/*****************************************************************************
+ * global constants
+*****************************************************************************/
+
+/*****************************************************************************
+ * global variables
+*****************************************************************************/
+
+// used by DelayUs() macro
+LIBBANK volatile BYTE _dcnt = 0;
+
+/*****************************************************************************
+ * static constants
+*****************************************************************************/
+
+/*****************************************************************************
+ * static variables
+*****************************************************************************/
+
+/*****************************************************************************
+ * static prototypes
+*****************************************************************************/
+
+/*****************************************************************************
+ * C functions
+*****************************************************************************/
+
+void DelayInit( void )
+{
+	// timer #0 as counter, 2 nsec counts (5 per usec)
+#ifdef _PIC18
+#if XTAL==40
+	T0CON = 0b10000000;	// prescalar = 2
+#else
+	T0CON = 0b10001000;	// no prescalar
+#endif
+#else
+	OPTION = 0b10000000;
+#endif
+}
+
+// short delays up to 255 usec
+void DelayUsec( BYTE n )
+{
+	// clear counter
+#ifdef _PIC18
+	TMR0H = 0;
+	TMR0L = 0;
+#else
+	TMR0 = 0;
+#endif
+	// # ticks per usec
+	n--;	// calling overhead
+	n *= 5;
+
+	// wait till count reaches
+#ifdef _PIC18
+	while ( TMR0L < n )
+		;
+#else
+	while ( TMR0 < n )
+		;
+#endif
+}
+
+// longer delays up to 10000 usec (10 msec)
+#ifdef _PIC18
+void DelayUsecW( WORD n )
+{
+	// clear counter
+	TMR0H = 0;
+	TMR0L = 0;
+
+	// 5 ticks per usec
+	n--;		// calling overhead
+	n *= 5;
+
+	// wait till count reaches
+	while ( TMR0 < n )
+		;
+}
+#endif