8bit PWM w. n SRs

/*
 * pwm8.c
 *
 *  Created on: 10.03.2019
 *      Author: harry
 */

#include "avr/io.h"
#include <avr/interrupt.h>
#include "pwm8.h"

#define LED_NUM     8               // must be a multiple of 8
#define SR_NUM      (LED_NUM / 8)

#define DEBUG

#define LATCH_PIN   PB1     // STCP
#define OE_PIN      PB2     // OE
#define MOSI_PIN    PB3     // Din
#define CLK_PIN     PB5     // SHCP

#define PORT_DIR    DDRB
#define LED_PORT    PORTB

#define LATCH()     LED_PORT |= (1 << LATCH_PIN),LED_PORT &= ~(1 << LATCH_PIN)

#ifdef DEBUG
#define TRIGGER_PIN PD2     // Debug-pin for triggering
#define TRIGGER_DIR DDRD
#define TRIGGER_PORT    PORTD
#define TRIGGER()   TRIGGER_PORT ^= (1 << TRIGGER_PIN) //,PULSE_PORT &= ~(1 << TRIGGER_PIN)
#endif

#define TIM_BSY()   tim_bsy = TRUE
#define TIM_RDY()   tim_bsy = FALSE
#define SPI_BSY()   spi_bsy = TRUE
#define SPI_RDY()   spi_bsy = FALSE

/*
 * timingg-setting
 */
#define DEADTIME    24

static volatile uint8_t pwm_buf[SR_NUM][8];

static volatile uint8_t tim_bsy = FALSE;
static volatile uint8_t spi_bsy = FALSE;
static volatile uint8_t bit_cnt = 0;
static volatile uint8_t sr_cnt;
static volatile uint8_t dummy;

/*
 * Public Functions
 */
void pwm8Init(void)
{
    // Initialize GPIOs
    PORT_DIR |= ((1 << LATCH_PIN) | (1 << OE_PIN)
             | (1 << MOSI_PIN) | (1 << CLK_PIN));   // define Outputs
    LED_PORT &= ~((1 << LATCH_PIN) | (1 << OE_PIN));    // Reset Latch and OE

#ifdef DEBUG
    TRIGGER_DIR |= (1 << TRIGGER_PIN);
#endif

    // Initialize SPI
    SPCR = (1 << SPIE) | (1 << SPE) | (1 << MSTR);  // enable SPI
    dummy = SPSR;   // clear pending interrupts
    dummy = SPDR;

    // Initialize Timer
    TCCR1A = (1 << COM1B1) | (1 << WGM11);
    TCCR1B = (1 << WGM12) | (1 << WGM13)
            | (1 << CS11);      // fast PWM-Mode
    TCNT1 = 0;
    GTCCR = ((1 << PSRSYNC) | (1 << TSM) | (1 << PSRASY));  // disable & synchronize prescaler

    TIFR1 = (1 << OCF1B);   // clear any pending interrupt
    TIMSK1 = (1 << ICIE1);  // enable OC0A interrupt
    sei();

    // Start first SPI-transfer
    sr_cnt = 0;
    SPDR = pwm_buf[sr_cnt][bit_cnt];
    SPI_BSY();
}

/*
 * Set LED Nr. lednr
 * to PWM-Value pwm_val
 */
void pwm8SetLED(uint8_t lednr, uint8_t pwm_val)
{
uint8_t pwm_mask, led_mask;
uint8_t sr, ln;

    sr = lednr >> 3;
    ln = lednr & 0b000001111;
    pwm_mask = 1;
    led_mask = 1 << ln;
    for (uint8_t i = 0; i < 8; i++)
    {
        if ((pwm_val & pwm_mask) == 0)
        {
            pwm_buf[sr][i] = pwm_buf[sr][i] | led_mask;
        }
        else
        {
            pwm_buf[sr][i] = pwm_buf[sr][i] & ~led_mask;
        }
        pwm_mask <<= 1;
    }
}

/*
 * Private Functions
 */

    // stat next Cycle
static void pwm8KickCycle(void)
{

    LATCH();    // enable new data
#ifdef DEBUG
    if (bit_cnt == 0)
        TRIGGER();
#endif

    // setup one-pulse-timer
    ICR1 = (1 << bit_cnt) + DEADTIME;
    OCR1B = DEADTIME;

    TCNT1 = 0;
    GTCCR = 0;              // enable Prescaler and start Timer
    TIM_BSY();              // timer running

    bit_cnt = (bit_cnt +1) & 0b00000111; // advance to next cycle
    SPDR = pwm_buf[0][bit_cnt]; // send next pattern in advance
    SPI_BSY();              // SPI running
}

/*
 * Interrupts
 *
 */
    // SPI-Interrupt
ISR( SPI_STC_vect )
{
    dummy = SPDR;
    if (++sr_cnt == SR_NUM)
    {
        SPI_RDY();
        sr_cnt = 0;
        if (tim_bsy == FALSE)
            pwm8KickCycle();        // in this special case, where the
                                    // SPI-transfer takes longer than the timer-cycle
    }
    else
    {
        SPDR = pwm_buf[sr_cnt][bit_cnt];
    }
}

     // Timer Interrupt
ISR( TIMER1_CAPT_vect )
{
    GTCCR = (1<<TSM) | (1<<PSRASY) | (1<<PSRSYNC); // halt all timers
    TIM_RDY();
    if (spi_bsy == FALSE)
        pwm8KickCycle();
}