by David Kott
struct RotaryEncoderStruct { int unused:4; // RB[0:3] int A:1; // RB4 int B:1; // RB5 int unused2:2; // RB6-7 }; struct RotaryEncoderStruct RotaryEncoder; #pragma BYTE PORTB = 0x06 #pragma BYTE RotaryEncoder = 0x06 // Place structure right over PORTB at location 0x06 USHORT g_usEncoderCount = 0; #pragma INT_RB void PortBInterrupt (void) { static BYTE OldPortB; BYTE byTemp; static struct RotaryEncoderStruct OldEncoder; if (OldPortB != (byTemp=(PORTB & 0x30))) { OldPortB = byTemp; if (RotaryEncoder.A == OldEncoder.A) { if (RotaryEncoder.B == RotaryEncoder.A) --g_usEncoderCount; else ++g_usEncoderCount; } else { OldEncoder.A = RotaryEncoder.A; if (RotaryEncoder.B == RotaryEncoder.A) ++g_usEncoderCount; else --g_usEncoderCount; } } // Handle more PORTB stuff here, like a button, or something. }
Questions:
How many machine cycles does this take to run (worst case)? This sets the maximum rotational speed of encoder that can be tracked (tempered by the processor clock speed and the encoder resolution in lines/rev, obviously)+
Comments:
file: /Techref/microchip/language/c/io/qenc-dk.htm, 2KB, , updated: 2019/10/19 12:20, local time: 2024/8/22 02:54,
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