rot_module.c

PIC_Hi-Tech_C_Mike_Pearces_I2C_routines Microchi PIC_Hi-Tech C_I2C_for_EEPROM_24LC01B Code

#define ROT1      RB7
#define ROT0      RB6
#define ROT1_IN  TRISB7=1
#define ROT0_IN  TRISB6=1
#define ROT_S0 0
#define ROT_S1 1
#define ROT_S2 2
#define ROT_S3 3

volatile unsigned char state,last_state,rotcount,last_rotcount;
volatile unsigned char rotdir,rot_min,rot_max;

void update_rotary_state(void){
  state = 0;
  if (ROT0) state = state | 0x01;  //set LSb
  if (ROT1) bitset(state,1);
  switch(state) {
  case ROT_S0:
    if (last_state == ROT_S1) {
      rotcount++; rotdir = 1; last_state = state;
    }else if (last_state == ROT_S2) {
      rotcount--;rotdir = 0; last_state = state;
    }break;
  case ROT_S1:
    if (last_state == ROT_S3) {
      rotcount++;rotdir=1; last_state = state;
    }
    else if (last_state == ROT_S0) {
      rotcount--; rotdir=0; last_state = state;
    }break;
  case ROT_S2:
    if (last_state == ROT_S0) {
      rotcount++; rotdir=1;last_state = state;
    }
    else if (last_state == ROT_S3) {
      rotcount--;rotdir=0;last_state = state;
    }break;
  case ROT_S3:
    if (last_state == ROT_S2) {
      rotcount++; rotdir=1;last_state = state;
    }
    else if (last_state == ROT_S1) {
      rotcount--; rotdir=0;last_state = state;
    }break;
  }
  if (rotdir){
    // incremented
    if (rotcount == (rot_max+1)) rotcount = rot_min;
  } else {
    //decremented
    if (!rot_min && (rotcount > rot_max)) rotcount = rot_max;
    else if (rotcount == (rot_min-1)) rotcount = rot_max;
  }
}