WAITPEQ and WAITPNE with PASM

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Introduction #

WAITPEQ and WAITPNE are two complimentary commands that pause execution in a cog until I/O pin(s) meet designated state(s).

WAITPEQ (WAIT until Pins EQual) pauses the cog until pin/s match,

WAITPNE (WAIT until Pins Not Equal) pauses the cog until pin/s no longer match.

Examples #

Using WAITPxx with a single pin:


        spin
        
            
        
     
WAITPEQ mypin,mypin   'wait for it to be high
WAITPNE mypin,mypin   'wait for it to be low
mypin long |<12       'P12 (pin 12)

How to wait for either of 2 pins to be low:


        spin
        
            
        
     
WAITPNE mytwopins,mytwopins   'wait for either one (or both) to be low 
mytwopins long |<12 | |<13    'the two pins ORed

How to wait for 2 pins where one is low and one is high:


        spin
        
            
        
     
WAITPEQ mypinstate,mytwopins  'wait for a match 
mytwopins  long |<12 | |<13   'the two pins ORed
mypinstate long |<12          'pin 12 needs be high and pin 13 needs to be low

How to wait for 2 pins where either one is high:


        spin
        
            
        
     
WAITPNE myzero,mytwopins    'wait for either one to be high 
mytwopins long |<12 | |<13  'the two pins ORed
myzero    long 0            'zero long for WAITPNE state comparison