In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Matthias09 wrote:

Hey guys, 

I am just about writing a program to read an encoder. To not miss a step I count both on falling and rising edges of Channel A, whenever Channel B is high. Therefore I switch the edge detection mode of Wakeup Byte WKED_B after every counted step from rising to falling and vise versa. 

Now I encountered the problem, that when WKED_B = %00000000 it counts only the rising edge of Channel A (which sits on Bit 0), like it should. However, when I set the WKED_B = %11111111 it detects BOTH rising and falling edges, rather than only falling ones. 

How come and what to do? :)

Here is my interrupt routine. Don't bother about the index channel part. That works fine.

[code]
'Channel A Interrupt
 IF int_storage <> %0001 THEN Index_Channel	'count only, if A alone fires (other possible combinations: 0010: index fires, 0011: index + A fires)
	
	IF signal_B = 0 THEN ISR_Exit		'count only, if B is high
	toggle led1

		IF edge = 0 THEN edge_0		'check the current edge detection mode,

			angle = angle + 1 	        'increment   
 			WKED_B  = %11111111 	'alter edge detection to falling edge on A
			edge = 0		                'change edge detection mode variable to 0 for next interrupt
			toggle led3
			GOTO ISR_Exit		        'all done, leave
		
		edge_0:
			angle = angle - 1 	        'decrement   
 			WKED_B  = %00000000 	'alter edge detection to rising edge on A
			edge = 1		                'change edge detection mode variable to 1 for next interrupt
			toggle led4
			GOTO ISR_Exit		         'all done, leave
			
 'Index Channel Interrupt
 Index_Channel:					'if index fires (no mater if A also fires), then reset angle to 90 deg.
	WKEN_B  = %11111100			'enable channel A interrupt (actually only has to be done after the first fire (as A is initally disabled). 
						                'but to a routine would slow the process, which is not good.
	angle = 90				                'reset angle
	Toggle Led2				
[/code]

This is what I do at startup:

[code]
 PROGRAM Start

 Start:

 WKPND_B = %00000000 				'clear pending register
 WKED_B  = %00000000 				'rising edge detect on the whole B Byte.
 WKEN_B  = %11111101 				'but only enable Bit 1 for interrupt for startup. All other Bits (except 0) can be used as I/Os without creating an interrupt
 edge = 1					                'first edge detection mode is rising edge (I define: rising edge = 1, falling edge = 0)
[/code]

Thank you very much!

Matthias

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