/* Shaft.c */

/* Utility functions for monitoring the shaft encoders */

/* Functions for reading left and right "velocities" using PA7s pulse counter */
/* and an interrupt routine (in speed.icb) to catch pulses on PA0 */

void init_velocity() /* Enable PA7 pulse counting and PA0 interrupt */
{ poke(0x1026,0b01010000); /* PACTL PA7 input, trigger on rising edge */
poke(0x1027,0); /* PACNT init to 0 */
left_clicks = 0; /* Global referenced by interrupt routine */
bit_clear(0x1021,0b10); /* TCTL2 Assign values to the two lowest order bits */
bit_set( 0x1021,0b01); /* of tctl2 without changing any other bits */
bit_set(0x1022,0b01); /* TMSK1 enable IC3 interrupts */
}

int get_left_clicks() /* Get the number of clicks and reset to 0 */
{ int clks = left_clicks; /* If called at regular intervals this funciton returns */
left_clicks = 0; /* the the left velocity in units of clicks per interval */
return clks; }

int get_right_clicks() /* Same as above for right Shaft encoder */
{ int clks = peek(0x1027); /* PACNT is only an 8-bit register -- be sure to */
poke(0x1027,0); /* call it often enough so that it dosen't overflow */
return clks; }