X-Git-Url: http://git.rot13.org//?a=blobdiff_plain;f=firmware%2Flib%2Fcommand.c;h=1de6f0a682ec0587304165bb0a517d1a6c7972a3;hb=dbcedaa279472080a2585e959a3146f3c5859556;hp=415171b732d9bc011f1c559acc8d6b1409d7a2ef;hpb=3924e6c10611bfeb4c3970a91bbe66c5ba7de6f2;p=goodfet

diff --git a/firmware/lib/command.c b/firmware/lib/command.c
index 415171b..1de6f0a 100644
--- a/firmware/lib/command.c
+++ b/firmware/lib/command.c
@@ -140,3 +140,57 @@ void msdelay(unsigned int ms){
   }
   //Using TimerA might be cleaner.
 }
+
+
+/* To better satisfy the somewhat odd timing requirements for
+   dsPIC33F/PIC24H ICSP programming, and for better control of GoodFET
+   timing more generally, here are a few delay routines that use Timer A.
+
+   Note that I wrote these referring only to the MSP430x2xx family
+   manual. Beware on MSP430x1xx chips. Further note that, assuming
+   some minor errors will be made, I try to err on the side of
+   delaying slightly longer than requested. */
+void prep_timer()
+{
+	BCSCTL2 = 0x00; /* In particular, use DCOCLK as SMCLK source with
+					   divider 1. Hence, Timer A ticks with system
+					   clock at 16 MHz. */
+
+	TACTL = 0x0204; /* Driven by SMCLK; disable Timer A interrupts;
+					   reset timer in case it was previously in use */
+}
+
+//! Delay for specified number of milliseconds (given 16 MHz clock)
+void delay_ms( unsigned int ms )
+{
+	// 16000 ticks = 1 ms
+	TACTL |= 0x20; // Start timer!
+	while (ms--) {
+		while (TAR < 16000)
+			asm( "nop" );
+		TACTL = 0x0224;
+	}
+	TACTL = 0x0204; // Reset Timer A, till next time
+}
+
+//! Delay for specified number of microseconds (given 16 MHz clock)
+void delay_us( unsigned int us )
+{
+	// 16 ticks = 1 us
+	TACTL |= 0x20; // Start timer!
+	while (us--) {
+		while (TAR < 16)
+			asm( "nop" );
+		TACTL = 0x0224;
+	}
+	TACTL = 0x0204; // Reset Timer A, till next time
+}
+
+//! Delay for specified number of clock ticks (16 MHz clock implies 62.5 ns per tick).
+void delay_ticks( unsigned int num_ticks )
+{
+	TACTL |= 0x20; // Start timer
+	while (TAR < num_ticks)
+		asm( "nop" );
+	TACTL = 0x0204; // Reset Timer A, till next time
+}