' -------------------------------------------------------------------------
  INTERRUPT NOCODE
' -------------------------------------------------------------------------

ASM

SETB rb.1			'debug pin(inside interrupt)
MOV myrtcc, RTCC		'preserve for comparison later

CLR FSR

ISR_Start:

	'a rollover here rtcc would be zero, and myrtcc should be 4
	'if this was an edge, myrtcc would be much higher like 230 etc

	CJA myrtcc,#5,@processedge			'if myrtcc > 5 then processedge
	
	JNB seenedge,@goback				'if seenedge = 0 then goback	'are we idle?

	inc validhigh

	jb validhigh.2,@goidle				'if validhigh = 4 then goidle

	'the next 5 lines of code write a 0 to the fram

	CLRB SCK		'make sure clock is low to start with(should already be low, though)
	NOP

	CLRB SI			'put a zero on the port
	NOP

	SETB SCK		'raise clock notifying chip to read the data

	IJNZ lobyte, goback
	IJNZ hibyte, goback
	inc superhibyte

goback:
		
	CLRB rb.1			'for debugging

	MOV W, #156			'255-100 = 156
	RETIW

goidle:

	CLRB seenedge			'erase the edge we saw before
		
	CLR validhigh			'reset and start over
			
	CLRB RB.1			'for debugging

	MOV w,#188			'255-188=67
	RETIW

processedge:

	MODE $09			'clear pending edge
	MOV !RB,#0

	CLR RTCC			'sync to the edge!
			
	SETB seenedge			'we've now seen an edge!

	CLR validhigh

	'next five lines of code store a 1 in the fram

	CLRB SCK		'make sure clock is low to start with(should already be low, though)
	NOP

	SETB SI			'put a one on the port
	NOP

	SETB SCK		'raise clock notifying chip to read the data

	IJNZ lobyte, retfromedge
	IJNZ hibyte, retfromedge
	inc superhibyte

retfromedge:

	CLRB RB.1			'for debugging

	MOV W,#155			'WAS 188, 150 = 2.68, 160 =2.54, 170=2.26 perfect
	RETIW

ENDASM