c1351.c File Reference

C1350 and C1351 implementation. More...

#include <inttypes.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <stdio.h>
#include "ioconfig.h"
#include "c1351.h"
#include "ps2.h"

Include dependency graph for c1351.c:

Functions
void	potmouse_init ()
	Init all C1351-related I/O and interrupts, but don't start yet.
void	potmouse_start (uint8_t m)
	Set mode and start working.
void	potmouse_movt (int16_t dx, int16_t dy, uint8_t button)
	Report movement from PS2 mouse.
void	potmouse_zero (uint16_t zero)
	Define zero-point in time (normally 320us).
	ISR (INT1_vect)
	ISR (TIMER1_OVF_vect)

---

Detailed Description

C1350 and C1351 implementation.

Everything that emulates C1351 (proportional) and C1350 (Joystick) mice. Every movement of a real mouse is signalled with potmouse_movt(). In proportional (analog) mode, INT1 interrupt senses SID measurement cycle start and loads timer OCR1A/OCR1B values with accordance to reported counter values.

In Joystick mode, pulses are generated on UP/DOWN/LEFT/RIGHT joystick lines every time a movement is reported.

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Function Documentation

ISR

(

TIMER1_OVF_vect

)

TIMER1 Overflow vector

Ends joystick emulator pulse.

                     {
    JOYDDR  &= ~(_BV(JOYFIRE) | _BV(JOYUP) | _BV(JOYDOWN) | _BV(JOYLEFT) | _BV(JOYRIGHT));
    POTDDR  &= ~_BV(POTX);
    TIMSK &= ~_BV(TOIE1);
}

ISR

(

INT1_vect

)

SID measuring cycle detected.

1. SID pulls POTX low
2. SID waits 256 cycles us
3. SID releases POTX
4. 0 to 255 cycles until the cap is charged

This handler stops the Timer1, clears OC1A/OC1B outputs, loads the timer with values precalculated in potmouse_movt() and starts the timer.

OC1A/OC1B (YPOT/XPOT) lines will go up by hardware. Normal SID cycle is 512us. Timer will overflow not before 65535us. Next cycle will begin before that so there's no need to stop the timer. Output compare match interrupts are thus not used.

               {
    // SID started to measure the pots, uuu

    // disable INT1 until the measurement cycle is complete
    // stop the timer
    TCCR1B = 0;
    
    // clear OC1A/OC1B:
    // 1. set output compare to clear OC1A/OC1B ("10" in table 37 on page 97)
    TCCR1A = _BV(COM1A1) | _BV(COM1B1);
    // 2. force output compare to make it happen
    TCCR1A |= _BV(FOC1A) | _BV(FOC1B);

    // Set OC1A/OC1B on Compare Match (Set output to high level) 
    // WGM13:0 = 00, normal mode: count from BOTTOM to MAX
    TCCR1A = _BV(COM1A1) | _BV(COM1A0) | _BV(COM1B1) | _BV(COM1B0);

    // load the timer 
    TCNT1 = 0;
    
    // init the output compare values 
    OCR1A = ocr1a_load;
    OCR1B = ocr1b_load;
    
    // start timer with prescaler clk/8 (1 count = 1us)
    TCCR1B = _BV(CS11);  
}

void potmouse_init

(

)

Init all C1351-related I/O and interrupts, but don't start yet.

                     {
    // Joystick outputs, all to Z and no pullup
    JOYPORT &= ~(_BV(JOYFIRE) | _BV(JOYUP) | _BV(JOYDOWN) | _BV(JOYLEFT) | _BV(JOYRIGHT)); 
    JOYDDR  &= ~(_BV(JOYFIRE) | _BV(JOYUP) | _BV(JOYDOWN) | _BV(JOYLEFT) | _BV(JOYRIGHT));
    
    // SID sensing port
    SENSEDDR  &= ~_BV(POTSENSE); // SENSE is input
    SENSEPORT &= ~_BV(POTSENSE); // pullup off, hi-biased by OC1B

    // SID POTX/POTY port
    POTPORT &= ~(_BV(POTX) | _BV(POTY));
    POTDDR  &= ~(_BV(POTX) | _BV(POTY));

    // prepare INT1
    GICR &= ~_BV(INT1);                     // disable INT1
    MCUCR &= ~(_BV(ISC11)|_BV(ISC10));  
    MCUCR |= _BV(ISC11);                    // ISC11:ISC10 == 10, @negedge   
    
    mode = POTMOUSE_C1351;
}

void potmouse_movt	(	int16_t	dx,
		int16_t	dy,
		uint8_t	button
	)

Report movement from PS2 mouse.

                                                           {
    uint16_t a, b;
    
    switch (mode) {
        case POTMOUSE_C1351:
            potmouse_xcounter = (potmouse_xcounter + dx) & 077; // modulo 64
            potmouse_ycounter = (potmouse_ycounter + dy) & 077;
        
            (button & 001) ? (JOYDDR |= _BV(JOYFIRE)) : (JOYDDR &= ~_BV(JOYFIRE));
            (button & 002) ? (JOYDDR |= _BV(JOYUP))   : (JOYDDR &= ~_BV(JOYUP));
            (button & 004) ? (JOYDDR |= _BV(JOYDOWN)) : (JOYDDR &= ~_BV(JOYDOWN));
            
            // scale should be 2x here, but for this particular chip, 66 counts work better where
            // 64 counds should be. so 66/64=100/96 and times two
            a = ocr_zero + potmouse_ycounter*200/96;
            b = ocr_zero + potmouse_xcounter*200/96;
            
            ocr1a_load = a;
            ocr1b_load = b;
            break;
        case POTMOUSE_JOYSTICK:
            JOYDDR  &= ~(_BV(JOYFIRE) | _BV(JOYUP) | _BV(JOYDOWN) | _BV(JOYLEFT) | _BV(JOYRIGHT));

            (dx < 0) ? (JOYDDR |= _BV(JOYLEFT)) : (JOYDDR &= ~_BV(JOYLEFT));
            (dx > 0) ? (JOYDDR |= _BV(JOYRIGHT)): (JOYDDR &= ~_BV(JOYRIGHT));
            (dy < 0) ? (JOYDDR |= _BV(JOYDOWN)) : (JOYDDR &= ~_BV(JOYDOWN));
            (dy > 0) ? (JOYDDR |= _BV(JOYUP))   : (JOYDDR &= ~_BV(JOYUP));
            (button & 001) ? (JOYDDR |= _BV(JOYFIRE)) : (JOYDDR &= ~_BV(JOYFIRE));
            (button & 002) ? (POTDDR |= _BV(POTX)) : (POTDDR &= ~_BV(POTX));
  
            TCNT1 = 65535-256;
            TCCR1A = 0;
            TCCR1B = _BV(CS12)|_BV(CS10);
            TIFR |= _BV(TOV1);
            TIMSK |= _BV(TOIE1);
            break;
    }
}

void potmouse_start

(

uint8_t

mode

)

Set mode and start working.

Parameters:

mode

see _potmode

                               {
    mode = m;
    switch (mode) {
        case POTMOUSE_C1351:
            // Initialize Timer1 and use OC1A/OC1B to output values
            // don't count yet    
            TCCR1B = 0; 
            
            // POTX/Y normally controlled by output compare unit
            // initially should be pulled up to provide high bias on SENSE pin
            POTDDR  |= _BV(POTX) | _BV(POTY);   // enable POTX/POTY as outputs
            POTPORT |= _BV(POTX) | _BV(POTY);   // output "1" on both
            
            GIFR |= _BV(INTF1);                     // clear INT1 flag
            GICR |= _BV(INT1);                      // enable INT1
            break;
        case POTMOUSE_JOYSTICK:
            // Joystick emulation
            // close directional pins for ~20ms while there is movement
            TCCR1B = 0;
            TCCR1A = 0;
            
            break;
    }
}

void potmouse_zero

(

uint16_t

zero

)

Define zero-point in time (normally 320us).

                                  {
    ocr_zero = zero;
}