From: ceb <ceb>
Date: Wed, 13 Oct 2004 01:30:04 +0000 (+0000)
Subject: Clare's first PIC program.
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=8bb858f4ee3ba66aba6413148be69007b2decc13;p=trains.git

Clare's first PIC program.
Observe the flashing LEDs! (hopefully)
---

diff --git a/cebpic/.cvsignore b/cebpic/.cvsignore
new file mode 100644
index 0000000..b9fbbeb
--- /dev/null
+++ b/cebpic/.cvsignore
@@ -0,0 +1,3 @@
+*.hex
+*.cod
+*.lst
diff --git a/cebpic/Makefile b/cebpic/Makefile
new file mode 100644
index 0000000..1e482f4
--- /dev/null
+++ b/cebpic/Makefile
@@ -0,0 +1,8 @@
+TARGETS=	led-flash.hex
+
+include ../pic.make
+
+clean:		pic-clean
+
+%-full.hex:	%.o config.o
+		$(LINK)
diff --git a/cebpic/led-flash.asm b/cebpic/led-flash.asm
new file mode 100644
index 0000000..ac85f3d
--- /dev/null
+++ b/cebpic/led-flash.asm
@@ -0,0 +1,53 @@
+; pin 21 (per-pic-led, RD2/PSP2/C1IN) states: high H = green, low L = red, float Z = black
+
+        include         /usr/share/gputils/header/p18f458.inc
+
+	code
+start
+; pin initial config
+	bcf	TRISE,4,0	; turn off PSPMODE (Data Sheet p100/101)
+; timer initial config
+	bcf	T0CON,0,0	; p107 Timer0 -> 16bit mode	
+	bcf	T0CON,5,0	; timer0 use internal clock
+	bcf	T0CON,3,0	; use prescaler
+	bsf	T0CON,2,0	; }	
+	bsf	T0CON,1,0	; } prescale value 1:256
+	bsf	T0CON,0,0	; }
+; actually do stuff
+	call 	green
+	call 	waiting
+	call 	black
+	call 	waiting
+	call 	red
+	call 	waiting
+	call 	black
+	call 	waiting
+	goto	start
+
+
+green
+	bcf	TRISD,2,0	; make pin RD2 an output (DS100)
+	bsf	LATD,2,0	; set pin RD2 H (green)
+	return
+
+black
+	bsf	TRISD,2,0	; make pin RD2 an input (i.e. set Z, black) (DS100)
+	return
+
+red
+	bcf	TRISD,2,0	; make pin RD2 an output (DS100)
+	bcf	LATD,2,0	; set pin RD2 L (red)
+	return
+
+waiting
+	bcf	INTCON,2,0	; clear timer0 interrupt bit (p109)
+	clrf	TMR0H,0		; p107 set high bit of timer0 to 0 (buffered, 
+				; so only actually set when write to tmr0l occurs)
+	clrf	TMR0L,0		; set low bit o timer0 - timer now set to 0000h
+loop
+	btfss	INTCON,2,0	; check whethr tiomer0 interrupt has been set -
+				; skip next instruction if so
+	bra	loop
+	return
+
+	end