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%11010 Smart-Pin scope mode trigger and arm values — Parallax Forums

%11010 Smart-Pin scope mode trigger and arm values

JonTitusJonTitus Posts: 193
in Propeller 2
The scope mode includes settings for a 6-bit arm and a 6-bit trigger value. That's a range from 0 to 63. How do these values relate to an analog-input signal that has an 8-bit resolution (0 to 255)? In an example program, these values get bitwise ANDed with $FC:
scp_x long (trigger_level & $FC)<<8 + (arm_level & $FC) + scope_filter   '  =  TTTTTT00AAAAAAFF

Perhaps the 2 LSBs of the arm and trigger values are internally set to %00 and the arm and trigger values then exist as multiples of four: 0, 4, 12, ... ... 252? --Jon

Comments

  • evanhevanh Posts: 15,187
    The 6 Most Significant bits of each. The relationship is in the main prop2 doc just under the Hann/Tukey filter shapes. There is also mention of the samples being "normalised" to 8 bits. They're only 5 or 6 bits effective anyway.
  • JonTitusJonTitus Posts: 193
    Thanks, EvanH.
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