X6R Firmware with batt low indicator LED V1.02

/* PYRO_momentary_charger version 1.0
 * Designed for use with X6R driver designed by pilotdog68, integrating original charger circuit.
 * Changelog
 *
 * 1.0 First stab at this based on MTN_momentary_temp version 1.0
 * 1.02 with Batt low indicator LED 1.02
 */

/*
 * NANJG 105C Diagram
 *                ---
 *              -|   |- VCC
 *       Switch -|   |- Voltage ADC
 *  CHARGER MON -|   |- PWM
 *          GND -|   |- ALT PWM
 *                ---
 *
 * FUSES
 *      I use these fuse settings
 *      Low:  0x75  (4.8MHz CPU without 8x divider, 9.4kHz phase-correct PWM or 18.75kHz fast-PWM)
 *      High: 0xff
 *
 *      For more details on these settings, visit http://github.com/JCapSolutions/blf-firmware/wiki/PWM-Frequency
 *
 * STARS
 *      Star 2 = Alt PWM output
 *      Star 3 = Charger on? input
 *      Star 4 = Switch input
 *
 * VOLTAGE
 *      Resistor values for voltage divider (reference BLF-VLD README for more info)
 *      Reference voltage can be anywhere from 1.0 to 1.2, so this cannot be all that accurate
 *
 *           VCC
 *            |
 *           Vd (~.25 v drop from protection diode)
 *            |
 *          1912 (R1 19,100 ohms)
 *            |
 *            |---- PB2 from MCU
 *            |
 *          4701 (R2 4,700 ohms)
 *            |
 *           GND
 *
 *      ADC = ((V_bat - V_diode) * R2   * 255) / ((R1    + R2  ) * V_ref)
 *      125 = ((3.0   - .25    ) * 4700 * 255) / ((19100 + 4700) * 1.1  )
 *      121 = ((2.9   - .25    ) * 4700 * 255) / ((19100 + 4700) * 1.1  )
 *
 *      Well 125 and 121 were too close, so it shut off right after lowering to low mode, so I went with
 *      130 and 120
 *
 *      To find out what value to use, plug in the target voltage (V) to this equation
 *          value = (V * 4700 * 255) / (23800 * 1.1)
 *
 */
#define F_CPU 4800000UL

// PWM Mode
#define PHASE 0b00000001
#define FAST  0b00000011

/*
 * =========================================================================
 * Settings to modify per driver
 */

//#define VOLTAGE_MON           // Comment out to disable - ramp down and eventual shutoff when battery is low
#define CHARGER_MON            // Comment out to disable - is charging cable connected
#define MODES           0,0,0,50,125,255        // Must be low to high, and must start with 0
#define ALT_MODES       0,3,32,0,0,0        // Must be low to high, and must start with 0, the defines the level for the secondary output. Comment out if no secondary output
#define MODE_PWM        0,PHASE,FAST,FAST,FAST,PHASE        // Define one per mode above. 0 tells the light to go to sleep
//#define TURBO             // Comment out to disable - full output with a step down after n number of seconds
                            // If turbo is enabled, it will be where 255 is listed in the modes above
//#define TURBO_TIMEOUT 5625 // How many WTD ticks before before dropping down (.016 sec each)
                            // 90  = 5625
                            // 120 = 7500

#define BATT_LOW        145 // When do we start ramping
#define BATT_CRIT       135 // When do we shut the light off
#define CHARGER_ON      190 // When we should lower the output
#define BATT_ADC_DELAY  188 // Delay in ticks between low-bat rampdowns (188 ~= 3s)
#define CHARGER_ADC_DELAY   5   // Delay in ticks before checking for charging cable (188 ~= 3s)
#define RED_INDICATORS
#define VOLTAGE_RED     145 // 25% Batt left

/*
 * =========================================================================
 */

#include <avr/pgmspace.h>
#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include <avr/wdt.h>
#include <avr/eeprom.h>
#include <avr/sleep.h>
//#include <avr/power.h>

#define SWITCH_PIN  PB3     // what pin the switch is connected to, which is Star 4
#define PWM_PIN     PB1
#define ALT_PWM_PIN PB0
#define RED_PIN     PB0
#define ADC_DIDR    ADC1D   // Digital input disable bit corresponding with PB2
#define ADC_PRSCL   0x06    // clk/64

#define PWM_LVL     OCR0B   // OCR0B is the output compare register for PB1
#define ALT_PWM_LVL OCR0A   // OCR0A is the output compare register for PB0

//#define DEBOUNCE_BOTH          // Comment out if you don't want to debounce the PRESS along with the RELEASE
                               // PRESS debounce is only needed in special cases where the switch can experience errant signals
#define DB_PRES_DUR 0b00000001 // time before we consider the switch pressed (after first realizing it was pressed)
#define DB_REL_DUR  0b00001111 // time before we consider the switch released
                               // each bit of 1 from the right equals 16ms, so 0x0f = 64ms

// Switch handling
#define LONG_PRESS_DUR   32 // How many WDT ticks until we consider a press a long press
                            // 32 is roughly .5 s
#define STROBE_DUR       70 // How many WDT ticks until we enter the hold-to-strobe mode

/*
 * The actual program
 * =========================================================================
 */

/*
 * global variables
 */
const uint8_t modes[]     = { MODES    };
#ifdef ALT_MODES
const uint8_t alt_modes[] = { ALT_MODES };
#endif
const uint8_t mode_pwm[] = { MODE_PWM };
volatile uint8_t mode_idx = 1;
volatile uint8_t press_duration = 0;
#ifdef VOLTAGE_MON
volatile uint8_t adc_channel = 1;   // MUX 01 corresponds with PB2, 02 for PB4. Will switch back and forth
#else
volatile uint8_t adc_channel = 2;   // MUX 01 corresponds with PB2, 02 for PB4. Will switch back and forth
#endif

// Debounce switch press value
#ifdef DEBOUNCE_BOTH
int is_pressed()
{
    static uint8_t pressed = 0;
    // Keep track of last switch values polled
    static uint8_t buffer = 0x00;
    // Shift over and tack on the latest value, 0 being low for pressed, 1 for pulled-up for released
    buffer = (buffer << 1) | ((PINB & (1 << SWITCH_PIN)) == 0);

    if (pressed) {
        // Need to look for a release indicator by seeing if the last switch status has been 0 for n number of polls
        pressed = (buffer & DB_REL_DUR);
    } else {
        // Need to look for pressed indicator by seeing if the last switch status was 1 for n number of polls
        pressed = ((buffer & DB_PRES_DUR) == DB_PRES_DUR);
    }

    return pressed;
}
#else
int is_pressed()
{
    // Keep track of last switch values polled
    static uint8_t buffer = 0x00;
    // Shift over and tack on the latest value, 0 being low for pressed, 1 for pulled-up for released
    buffer = (buffer << 1) | ((PINB & (1 << SWITCH_PIN)) == 0);

    return (buffer & DB_REL_DUR);
}
#endif

void next_mode() {
    if (++mode_idx >= sizeof(modes)) {
        // Wrap around
        mode_idx = 2;
    }
}

void prev_mode() {
    if (mode_idx == 0) {
        // Wrap around
        mode_idx = sizeof(modes) - 1;
    } else {
        --mode_idx;
    }
}

inline void PCINT_on() {
    // Enable pin change interrupts
    GIMSK |= (1 << PCIE);
}

inline void PCINT_off() {
    // Disable pin change interrupts
    GIMSK &= ~(1 << PCIE);
}

// Need an interrupt for when pin change is enabled to ONLY wake us from sleep.
// All logic of what to do when we wake up will be handled in the main loop.
EMPTY_INTERRUPT(PCINT0_vect);

inline void WDT_on() {
    // Setup watchdog timer to only interrupt, not reset, every 16ms.
    cli();                          // Disable interrupts
    wdt_reset();                    // Reset the WDT
    WDTCR |= (1<<WDCE) | (1<<WDE);  // Start timed sequence
    WDTCR = (1<<WDTIE);             // Enable interrupt every 16ms
    sei();                          // Enable interrupts
}

inline void WDT_off()
{
    cli();                          // Disable interrupts
    wdt_reset();                    // Reset the WDT
    MCUSR &= ~(1<<WDRF);            // Clear Watchdog reset flag
    WDTCR |= (1<<WDCE) | (1<<WDE);  // Start timed sequence
    WDTCR = 0x00;                   // Disable WDT
    sei();                          // Enable interrupts
}

void ADC_on() {
    ADMUX  = (1 << REFS0) | (1 << ADLAR) | adc_channel; // 1.1v reference, left-adjust, ADC1/PB2 or ADC2/PB3
    DIDR0 |= (1 << ADC_DIDR);                           // disable digital input on ADC pin to reduce power consumption
    ADCSRA = (1 << ADEN ) | (1 << ADSC ) | ADC_PRSCL;   // enable, start, prescale, Single Conversion mode
}

void ADC_off() {
    ADCSRA &= ~(1 << ADSC); //ADC off
}

void sleep_until_switch_press()
{
    // This routine takes up a lot of program memory :(
    // Turn the WDT off so it doesn't wake us from sleep
    // Will also ensure interrupts are on or we will never wake up
    WDT_off();
    // Need to reset press duration since a button release wasn't recorded
    press_duration = 0;
    // Enable a pin change interrupt to wake us up
    // However, we have to make sure the switch is released otherwise we will wake when the user releases the switch
    while (is_pressed()) {
        _delay_ms(16);
    }
    PCINT_on();
    // Enable sleep mode set to Power Down that will be triggered by the sleep_mode() command.
    //set_sleep_mode(SLEEP_MODE_PWR_DOWN);
    // Now go to sleep
    sleep_mode();
    // Hey, someone must have pressed the switch!!
    // Disable pin change interrupt because it's only used to wake us up
    PCINT_off();
    // Turn the WDT back on to check for switch presses
    WDT_on();
    // Go back to main program
}

// The watchdog timer is called every 16ms
ISR(WDT_vect) {

    //static uint8_t  press_duration = 0;  // Pressed or not pressed
    static uint16_t turbo_ticks = 0;
    static uint16_t batt_adc_ticks = BATT_ADC_DELAY;
    static uint16_t charger_adc_ticks = CHARGER_ADC_DELAY;
    static uint8_t  lowbatt_cnt = 0;
    static uint8_t  highest_mode_idx = 255;

    if (is_pressed()) {
        if (press_duration < 255) {
            press_duration++;
        }

        if (press_duration == LONG_PRESS_DUR) {
            // Long press
                prev_mode();
            highest_mode_idx = mode_idx;
        }
                //hold-to-strobe code
        #ifdef STROBE_DUR
        if (press_duration == STROBE_DUR) {
            while(is_pressed()){
                            //Exit loop once switch is let go
                PWM_LVL = 255;
                _delay_ms(50);
                PWM_LVL=0;
                _delay_ms(50);
                                //Can alter values to change strobe duration
            }
        mode_idx;
                //Return to the previous mode because we actually went back a
                //mode before entering strobe
        }
        #endif
        // Just always reset turbo timer whenever the button is pressed
        turbo_ticks = 0;
        // Same with the ramp down delay
        batt_adc_ticks = BATT_ADC_DELAY;
        charger_adc_ticks = CHARGER_ADC_DELAY;

    } else {

        // Not pressed
        if (press_duration > 0 && press_duration < LONG_PRESS_DUR) {
            // Short press
                next_mode();
            highest_mode_idx = mode_idx;
        } else {
            // Only do turbo check when switch isn't pressed
        #ifdef TURBO
            if (modes[mode_idx] == 255) {
                turbo_ticks++;
                if (turbo_ticks > TURBO_TIMEOUT) {
                    // Go to the previous mode
                    prev_mode();
                }
            }
        #endif
            // Only do voltage monitoring when the switch isn't pressed
            // See if conversion is done. We moved this up here because we want to stay on
            // the current ADC input until the conversion is done, and then switch to the new
            // input, start the monitoring
            if (batt_adc_ticks > 0) {
                --batt_adc_ticks;
            }
            if (charger_adc_ticks > 0) {
                --charger_adc_ticks;
            }
            if (ADCSRA & (1 << ADIF)) {
                if (adc_channel == 0x01) {

                    if (batt_adc_ticks == 0) {
                        // See if voltage is lower than what we were looking for
                        if (ADCH < ((mode_idx == 1) ? BATT_CRIT : BATT_LOW)) {
                            ++lowbatt_cnt;
                        } else {
                            lowbatt_cnt = 0;
                        }
                        #ifdef RED_INDICATORS
                    if (voltage < VOLTAGE_RED) {
                        // turn on red LED
                        DDRB = (1 << PWM_PIN) | (1 << RED_PIN);
                        PORTB |= (1 << RED_PIN);
                    }
#endif

                        // See if it's been low for a while
                        if (lowbatt_cnt >= 4) {
                            prev_mode();
                            highest_mode_idx = mode_idx;
                            lowbatt_cnt = 0;
                            // If we reach 0 here, main loop will go into sleep mode
                            // Restart the counter to when we step down again
                            batt_adc_ticks = BATT_ADC_DELAY;
                            charger_adc_ticks = CHARGER_ADC_DELAY;
                        }
                    }
                    // Switch ADC to charger monitoring
                    adc_channel = 0x02;
                    ADMUX = ((ADMUX & 0b11111100) | adc_channel);
                } else if (adc_channel == 0x02) {

                    if (charger_adc_ticks == 0) {
                        // See if charger is higher than the high threshold
                        if (ADCH > ((mode_idx == 1) ? 255 : CHARGER_ON)) {
                            mode_idx = 0;
                            charger_adc_ticks = CHARGER_ADC_DELAY;
                        } else {
                            mode_idx;
                            charger_adc_ticks = CHARGER_ADC_DELAY;
                        }
                    }
                    #ifdef VOLTAGE_MON
                    // Switch ADC to battery monitoring
                    adc_channel = 0x01;
                    ADMUX = ((ADMUX & 0b11111100) | adc_channel);
                    #endif;
                }
            }
            // Start conversion for next time through
            ADCSRA |= (1 << ADSC);
        }
        press_duration = 0;
    }
}

int main(void)
{
    // Set all ports to input, and turn pull-up resistors on for the inputs we are using
    DDRB = 0x00;
    PORTB = (1 << SWITCH_PIN);

    // Set the switch as an interrupt for when we turn pin change interrupts on
    PCMSK = (1 << SWITCH_PIN);

    // Set PWM pin to output
    #ifdef ALT_MODES
    DDRB = (1 << PWM_PIN) | (1 << ALT_PWM_PIN);
    #else
    DDRB = (1 << PWM_PIN);
    #endif

    // Set timer to do PWM for correct output pin and set prescaler timing
    //TCCR0A = 0x23; // phase corrected PWM is 0x21 for PB1, fast-PWM is 0x23
    TCCR0B = 0x01; // pre-scaler for timer (1 => 1, 2 => 8, 3 => 64...)

    // Turn features on or off as needed
    ADC_on();
    ACSR   |=  (1<<7); //AC off

    // Enable sleep mode set to Power Down that will be triggered by the sleep_mode() command.
    set_sleep_mode(SLEEP_MODE_PWR_DOWN);
    sleep_until_switch_press();

    uint8_t last_mode_idx = 0;

    while(1) {
        // We will never leave this loop.  The WDT will interrupt to check for switch presses and
        // will change the mode if needed.  If this loop detects that the mode has changed, run the
        // logic for that mode while continuing to check for a mode change.
        if (mode_idx != last_mode_idx) {
            // The WDT changed the mode.
            if (mode_idx > 0) {
                // No need to change the mode if we are just turning the light off
                // Check if the PWM mode is different
                if (mode_pwm[last_mode_idx] != mode_pwm[mode_idx]) {
                    #ifdef ALT_MODES
                    TCCR0A = mode_pwm[mode_idx] | 0b10100000;  // Use both outputs
                    #else
                    TCCR0A = mode_pwm[mode_idx] | 0b00100000;  // Only use the normal output
                    #endif
                }
            }
            PWM_LVL     = modes[mode_idx];
            #ifdef ALT_MODES
            ALT_PWM_LVL = alt_modes[mode_idx];
            #endif
            last_mode_idx = mode_idx;
            if (mode_pwm[mode_idx] == 0) {
                _delay_ms(1); // Need this here, maybe instructions for PWM output not getting executed before shutdown?
                // Go to sleep
                sleep_until_switch_press();
            }
        }
    }

    return 0; // Standard Return Code
}