/**
 * @file ds1809_device.c
 * @brief DS1809 pulse-based control helper.
 */

#include "ds1809_device.h"

#include "main.h"

#define DS1809_POSITION_COUNT 64u
#define DS1809_CPU_PULSE_WIDTH_MS 2u
#define DS1809_CPU_INTER_PULSE_HIGH_MS 2u
#define DS1809_CONTROL_PORT_READY_DELAY_MS 10u

static void ds1809_drive_idle_high(void)
{
    HAL_GPIO_WritePin(DS1809_UC_GPIO_Port, DS1809_UC_Pin, GPIO_PIN_SET);
    HAL_GPIO_WritePin(DS1809_DC_GPIO_Port, DS1809_DC_Pin, GPIO_PIN_SET);
}

static void ds1809_pulse_direction(uint8_t increment,
                                   uint8_t decrement,
                                   uint16_t count,
                                   uint16_t low_time_ms,
                                   uint16_t high_time_ms)
{
    uint16_t pulse_index;

    if ((count == 0u) || ((increment == 0u) && (decrement == 0u)))
    {
        ds1809_drive_idle_high();
        return;
    }

    ds1809_drive_idle_high();

    for (pulse_index = 0u; pulse_index < count; ++pulse_index)
    {
        if (increment != 0u)
        {
            HAL_GPIO_WritePin(DS1809_UC_GPIO_Port, DS1809_UC_Pin, GPIO_PIN_RESET);
        }
        if (decrement != 0u)
        {
            HAL_GPIO_WritePin(DS1809_DC_GPIO_Port, DS1809_DC_Pin, GPIO_PIN_RESET);
        }

        HAL_Delay(low_time_ms);
        ds1809_drive_idle_high();
        HAL_Delay(high_time_ms);
    }
}

void ds1809_pulse(uint8_t increment, uint8_t decrement, uint16_t count, uint16_t pulse_ms)
{
    if (pulse_ms < DS1809_CPU_PULSE_WIDTH_MS)
    {
        pulse_ms = DS1809_CPU_PULSE_WIDTH_MS;
    }

    ds1809_pulse_direction(increment, decrement, count, pulse_ms, pulse_ms);
}

void ds1809_apply_position_from_min(uint8_t position_from_min)
{
    /*
     * DS1809 CPU-driven timing requirements from the local datasheet:
     * - a pulse must stay low for longer than 1 ms to count as a step;
     * - repetitive pulses need at least 1 ms of high time between steps;
     * - the control inputs are locked out for at least 10 ms after power-up.
     *
     * Use 2 ms low/high timing for margin, always drive to the RL end first,
     * then walk back up to the requested absolute position.
     */
    if (position_from_min >= DS1809_POSITION_COUNT)
    {
        position_from_min = (uint8_t)(DS1809_POSITION_COUNT - 1u);
    }

    HAL_Delay(DS1809_CONTROL_PORT_READY_DELAY_MS);
    ds1809_pulse_direction(0u, 1u, DS1809_POSITION_COUNT, DS1809_CPU_PULSE_WIDTH_MS, DS1809_CPU_INTER_PULSE_HIGH_MS);
    ds1809_pulse_direction(1u, 0u, position_from_min, DS1809_CPU_PULSE_WIDTH_MS, DS1809_CPU_INTER_PULSE_HIGH_MS);
}