unleashed-firmware/lib/digital_signal/digital_signal.c

#include "digital_signal.h"

#include <furi.h>
#include <furi_hal.h>
#include <furi_hal_resources.h>
#include <math.h>

#include <stm32wbxx_ll_dma.h>
#include <stm32wbxx_ll_tim.h>

/* must be on bank B */
#define DEBUG_OUTPUT gpio_ext_pb3

struct ReloadBuffer {
    uint32_t* buffer; /* DMA ringbuffer */
    uint32_t size; /* maximum entry count of the ring buffer */
    uint32_t write_pos; /* current buffer write index */
    uint32_t read_pos; /* current buffer read index */
    bool dma_active;
};

struct DigitalSequence {
    uint8_t signals_size;
    bool bake;
    uint32_t sequence_used;
    uint32_t sequence_size;
    DigitalSignal** signals;
    uint8_t* sequence;
    const GpioPin* gpio;
    uint32_t send_time;
    bool send_time_active;
    LL_DMA_InitTypeDef dma_config_gpio;
    LL_DMA_InitTypeDef dma_config_timer;
    uint32_t* gpio_buff;
    struct ReloadBuffer* dma_buffer;
};

struct DigitalSignalInternals {
    uint64_t factor;
    uint32_t reload_reg_entries;
    uint32_t reload_reg_remainder;
    uint32_t gpio_buff[2];
    const GpioPin* gpio;
    LL_DMA_InitTypeDef dma_config_gpio;
    LL_DMA_InitTypeDef dma_config_timer;
};

#define TAG "DigitalSignal"

#define F_TIM (64000000.0)
#define T_TIM 1562 /* 15.625 ns *100 */
#define T_TIM_DIV2 781 /* 15.625 ns / 2 *100 */

/* maximum entry count of the sequence dma ring buffer */
#define SEQUENCE_DMA_RINGBUFFER_SIZE 32
/* maximum number of DigitalSignals in a sequence */
#define SEQUENCE_SIGNALS_SIZE 32
/*
 * if sequence size runs out from the initial value passed to digital_sequence_alloc
 * the size will be increased by this amount and reallocated
 */
#define SEQUENCE_SIZE_REALLOCATE_INCREMENT 256

DigitalSignal* digital_signal_alloc(uint32_t max_edges_cnt) {
    DigitalSignal* signal = malloc(sizeof(DigitalSignal));
    signal->start_level = true;
    signal->edges_max_cnt = max_edges_cnt;
    signal->edge_timings = malloc(signal->edges_max_cnt * sizeof(uint32_t));
    signal->edge_cnt = 0;
    signal->reload_reg_buff = malloc(signal->edges_max_cnt * sizeof(uint32_t));

    signal->internals = malloc(sizeof(DigitalSignalInternals));
    DigitalSignalInternals* internals = signal->internals;

    internals->factor = 1024 * 1024;

    internals->dma_config_gpio.Direction = LL_DMA_DIRECTION_MEMORY_TO_PERIPH;
    internals->dma_config_gpio.Mode = LL_DMA_MODE_CIRCULAR;
    internals->dma_config_gpio.PeriphOrM2MSrcIncMode = LL_DMA_PERIPH_NOINCREMENT;
    internals->dma_config_gpio.MemoryOrM2MDstIncMode = LL_DMA_MEMORY_INCREMENT;
    internals->dma_config_gpio.PeriphOrM2MSrcDataSize = LL_DMA_PDATAALIGN_WORD;
    internals->dma_config_gpio.MemoryOrM2MDstDataSize = LL_DMA_MDATAALIGN_WORD;
    internals->dma_config_gpio.NbData = 2;
    internals->dma_config_gpio.PeriphRequest = LL_DMAMUX_REQ_TIM2_UP;
    internals->dma_config_gpio.Priority = LL_DMA_PRIORITY_VERYHIGH;

    internals->dma_config_timer.PeriphOrM2MSrcAddress = (uint32_t) & (TIM2->ARR);
    internals->dma_config_timer.Direction = LL_DMA_DIRECTION_MEMORY_TO_PERIPH;
    internals->dma_config_timer.Mode = LL_DMA_MODE_NORMAL;
    internals->dma_config_timer.PeriphOrM2MSrcIncMode = LL_DMA_PERIPH_NOINCREMENT;
    internals->dma_config_timer.MemoryOrM2MDstIncMode = LL_DMA_MEMORY_INCREMENT;
    internals->dma_config_timer.PeriphOrM2MSrcDataSize = LL_DMA_PDATAALIGN_WORD;
    internals->dma_config_timer.MemoryOrM2MDstDataSize = LL_DMA_MDATAALIGN_WORD;
    internals->dma_config_timer.PeriphRequest = LL_DMAMUX_REQ_TIM2_UP;
    internals->dma_config_timer.Priority = LL_DMA_PRIORITY_HIGH;

    return signal;
}

void digital_signal_free(DigitalSignal* signal) {
    furi_assert(signal);

    free(signal->edge_timings);
    free(signal->reload_reg_buff);
    free(signal->internals);
    free(signal);
}

bool digital_signal_append(DigitalSignal* signal_a, DigitalSignal* signal_b) {
    furi_assert(signal_a);
    furi_assert(signal_b);

    if(signal_a->edges_max_cnt < signal_a->edge_cnt + signal_b->edge_cnt) {
        return false;
    }
    /* in case there are no edges in our target signal, the signal to append makes the rules */
    if(!signal_a->edge_cnt) {
        signal_a->start_level = signal_b->start_level;
    }
    bool end_level = signal_a->start_level;
    if(signal_a->edge_cnt) {
        end_level = signal_a->start_level ^ !(signal_a->edge_cnt % 2);
    }
    uint8_t start_copy = 0;
    if(end_level == signal_b->start_level) {
        if(signal_a->edge_cnt) {
            signal_a->edge_timings[signal_a->edge_cnt - 1] += signal_b->edge_timings[0];
            start_copy += 1;
        } else {
            signal_a->edge_timings[signal_a->edge_cnt] += signal_b->edge_timings[0];
        }
    }

    for(size_t i = 0; i < signal_b->edge_cnt - start_copy; i++) {
        signal_a->edge_timings[signal_a->edge_cnt + i] = signal_b->edge_timings[start_copy + i];
    }
    signal_a->edge_cnt += signal_b->edge_cnt - start_copy;

    return true;
}

bool digital_signal_get_start_level(DigitalSignal* signal) {
    furi_assert(signal);

    return signal->start_level;
}

uint32_t digital_signal_get_edges_cnt(DigitalSignal* signal) {
    furi_assert(signal);

    return signal->edge_cnt;
}

void digital_signal_add(DigitalSignal* signal, uint32_t ticks) {
    furi_assert(signal);
    furi_assert(signal->edge_cnt < signal->edges_max_cnt);

    signal->edge_timings[signal->edge_cnt++] = ticks;
}

void digital_signal_add_pulse(DigitalSignal* signal, uint32_t ticks, bool level) {
    furi_assert(signal);
    furi_assert(signal->edge_cnt < signal->edges_max_cnt);

    /* virgin signal? add it as the only level */
    if(signal->edge_cnt == 0) {
        signal->start_level = level;
        signal->edge_timings[signal->edge_cnt++] = ticks;
    } else {
        bool end_level = signal->start_level ^ !(signal->edge_cnt % 2);

        if(level != end_level) {
            signal->edge_timings[signal->edge_cnt++] = ticks;
        } else {
            signal->edge_timings[signal->edge_cnt - 1] += ticks;
        }
    }
}

uint32_t digital_signal_get_edge(DigitalSignal* signal, uint32_t edge_num) {
    furi_assert(signal);
    furi_assert(edge_num < signal->edge_cnt);

    return signal->edge_timings[edge_num];
}

void digital_signal_prepare_arr(DigitalSignal* signal) {
    furi_assert(signal);

    DigitalSignalInternals* internals = signal->internals;

    /* set up signal polarities */
    if(internals->gpio) {
        uint32_t bit_set = internals->gpio->pin;
        uint32_t bit_reset = internals->gpio->pin << 16;

#ifdef DEBUG_OUTPUT
        bit_set |= DEBUG_OUTPUT.pin;
        bit_reset |= DEBUG_OUTPUT.pin << 16;
#endif

        if(signal->start_level) {
            internals->gpio_buff[0] = bit_set;
            internals->gpio_buff[1] = bit_reset;
        } else {
            internals->gpio_buff[0] = bit_reset;
            internals->gpio_buff[1] = bit_set;
        }
    }

    /* set up edge timings */
    internals->reload_reg_entries = 0;

    for(size_t pos = 0; pos < signal->edge_cnt; pos++) {
        uint32_t pulse_duration = signal->edge_timings[pos] + internals->reload_reg_remainder;
        if(pulse_duration < 10 || pulse_duration > 10000000) {
            /*FURI_LOG_D(
                TAG,
                "[prepare] pulse_duration out of range: %lu = %lu * %llu",
                pulse_duration,
                signal->edge_timings[pos],
                internals->factor);*/
            pulse_duration = 100;
        }
        uint32_t pulse_ticks = (pulse_duration + T_TIM_DIV2) / T_TIM;
        internals->reload_reg_remainder = pulse_duration - (pulse_ticks * T_TIM);

        if(pulse_ticks > 1) {
            signal->reload_reg_buff[internals->reload_reg_entries++] = pulse_ticks - 1;
        }
    }
}

static void digital_signal_stop_dma() {
    LL_DMA_DisableChannel(DMA1, LL_DMA_CHANNEL_1);
    LL_DMA_DisableChannel(DMA1, LL_DMA_CHANNEL_2);
    LL_DMA_ClearFlag_TC1(DMA1);
    LL_DMA_ClearFlag_TC2(DMA1);
}

static void digital_signal_stop_timer() {
    LL_TIM_DisableCounter(TIM2);
    LL_TIM_DisableUpdateEvent(TIM2);
    LL_TIM_DisableDMAReq_UPDATE(TIM2);

    furi_hal_bus_disable(FuriHalBusTIM2);
}

static void digital_signal_setup_timer() {
    furi_hal_bus_enable(FuriHalBusTIM2);

    LL_TIM_SetCounterMode(TIM2, LL_TIM_COUNTERMODE_UP);
    LL_TIM_SetClockDivision(TIM2, LL_TIM_CLOCKDIVISION_DIV1);
    LL_TIM_SetPrescaler(TIM2, 0);
    LL_TIM_SetAutoReload(TIM2, 0xFFFFFFFF);
    LL_TIM_SetCounter(TIM2, 0);
}

static void digital_signal_start_timer() {
    LL_TIM_EnableCounter(TIM2);
    LL_TIM_EnableUpdateEvent(TIM2);
    LL_TIM_EnableDMAReq_UPDATE(TIM2);
    LL_TIM_GenerateEvent_UPDATE(TIM2);
}

static bool digital_signal_setup_dma(DigitalSignal* signal) {
    furi_assert(signal);
    DigitalSignalInternals* internals = signal->internals;

    if(!signal->internals->reload_reg_entries) {
        return false;
    }
    digital_signal_stop_dma();

    internals->dma_config_gpio.MemoryOrM2MDstAddress = (uint32_t)internals->gpio_buff;
    internals->dma_config_gpio.PeriphOrM2MSrcAddress = (uint32_t) & (internals->gpio->port->BSRR);
    internals->dma_config_timer.MemoryOrM2MDstAddress = (uint32_t)signal->reload_reg_buff;
    internals->dma_config_timer.NbData = signal->internals->reload_reg_entries;

    /* set up DMA channel 1 and 2 for GPIO and timer copy operations */
    LL_DMA_Init(DMA1, LL_DMA_CHANNEL_1, &internals->dma_config_gpio);
    LL_DMA_Init(DMA1, LL_DMA_CHANNEL_2, &internals->dma_config_timer);

    /* enable both DMA channels */
    LL_DMA_EnableChannel(DMA1, LL_DMA_CHANNEL_1);
    LL_DMA_EnableChannel(DMA1, LL_DMA_CHANNEL_2);

    return true;
}

void digital_signal_send(DigitalSignal* signal, const GpioPin* gpio) {
    furi_assert(signal);

    if(!signal->edge_cnt) {
        return;
    }

    /* Configure gpio as output */
    signal->internals->gpio = gpio;
    furi_hal_gpio_init(
        signal->internals->gpio, GpioModeOutputPushPull, GpioPullNo, GpioSpeedVeryHigh);

    digital_signal_prepare_arr(signal);

    digital_signal_setup_dma(signal);
    digital_signal_setup_timer();
    digital_signal_start_timer();

    while(!LL_DMA_IsActiveFlag_TC2(DMA1)) {
    }

    digital_signal_stop_timer();
    digital_signal_stop_dma();
}

static void digital_sequence_alloc_signals(DigitalSequence* sequence, uint32_t size) {
    sequence->signals_size = size;
    sequence->signals = malloc(sequence->signals_size * sizeof(DigitalSignal*));
}

static void digital_sequence_alloc_sequence(DigitalSequence* sequence, uint32_t size) {
    sequence->sequence_used = 0;
    sequence->sequence_size = size;
    sequence->sequence = malloc(sequence->sequence_size);
    sequence->send_time = 0;
    sequence->send_time_active = false;
}

DigitalSequence* digital_sequence_alloc(uint32_t size, const GpioPin* gpio) {
    furi_assert(gpio);

    DigitalSequence* sequence = malloc(sizeof(DigitalSequence));

    sequence->gpio = gpio;
    sequence->bake = false;

    sequence->dma_buffer = malloc(sizeof(struct ReloadBuffer));
    sequence->dma_buffer->size = SEQUENCE_DMA_RINGBUFFER_SIZE;
    sequence->dma_buffer->buffer = malloc(sequence->dma_buffer->size * sizeof(uint32_t));

    sequence->dma_config_gpio.Direction = LL_DMA_DIRECTION_MEMORY_TO_PERIPH;
    sequence->dma_config_gpio.Mode = LL_DMA_MODE_CIRCULAR;
    sequence->dma_config_gpio.PeriphOrM2MSrcIncMode = LL_DMA_PERIPH_NOINCREMENT;
    sequence->dma_config_gpio.MemoryOrM2MDstIncMode = LL_DMA_MEMORY_INCREMENT;
    sequence->dma_config_gpio.PeriphOrM2MSrcDataSize = LL_DMA_PDATAALIGN_WORD;
    sequence->dma_config_gpio.MemoryOrM2MDstDataSize = LL_DMA_MDATAALIGN_WORD;
    sequence->dma_config_gpio.NbData = 2;
    sequence->dma_config_gpio.PeriphRequest = LL_DMAMUX_REQ_TIM2_UP;
    sequence->dma_config_gpio.Priority = LL_DMA_PRIORITY_VERYHIGH;

    sequence->dma_config_timer.Direction = LL_DMA_DIRECTION_MEMORY_TO_PERIPH;
    sequence->dma_config_timer.Mode = LL_DMA_MODE_CIRCULAR;
    sequence->dma_config_timer.PeriphOrM2MSrcIncMode = LL_DMA_PERIPH_NOINCREMENT;
    sequence->dma_config_timer.MemoryOrM2MDstIncMode = LL_DMA_MEMORY_INCREMENT;
    sequence->dma_config_timer.PeriphOrM2MSrcDataSize = LL_DMA_PDATAALIGN_WORD;
    sequence->dma_config_timer.MemoryOrM2MDstDataSize = LL_DMA_MDATAALIGN_WORD;
    sequence->dma_config_timer.PeriphOrM2MSrcAddress = (uint32_t) & (TIM2->ARR);
    sequence->dma_config_timer.MemoryOrM2MDstAddress = (uint32_t)sequence->dma_buffer->buffer;
    sequence->dma_config_timer.NbData = sequence->dma_buffer->size;
    sequence->dma_config_timer.PeriphRequest = LL_DMAMUX_REQ_TIM2_UP;
    sequence->dma_config_timer.Priority = LL_DMA_PRIORITY_HIGH;

    digital_sequence_alloc_signals(sequence, SEQUENCE_SIGNALS_SIZE);
    digital_sequence_alloc_sequence(sequence, size);

    return sequence;
}

void digital_sequence_free(DigitalSequence* sequence) {
    furi_assert(sequence);

    free(sequence->signals);
    free(sequence->sequence);
    free(sequence->dma_buffer->buffer);
    free(sequence->dma_buffer);
    free(sequence);
}

void digital_sequence_set_signal(
    DigitalSequence* sequence,
    uint8_t signal_index,
    DigitalSignal* signal) {
    furi_assert(sequence);
    furi_assert(signal);
    furi_assert(signal_index < sequence->signals_size);

    sequence->signals[signal_index] = signal;
    signal->internals->gpio = sequence->gpio;
    signal->internals->reload_reg_remainder = 0;

    digital_signal_prepare_arr(signal);
}

void digital_sequence_set_sendtime(DigitalSequence* sequence, uint32_t send_time) {
    furi_assert(sequence);

    sequence->send_time = send_time;
    sequence->send_time_active = true;
}

void digital_sequence_add(DigitalSequence* sequence, uint8_t signal_index) {
    furi_assert(sequence);
    furi_assert(signal_index < sequence->signals_size);

    if(sequence->sequence_used >= sequence->sequence_size) {
        sequence->sequence_size += SEQUENCE_SIZE_REALLOCATE_INCREMENT;
        sequence->sequence = realloc(sequence->sequence, sequence->sequence_size); //-V701
        furi_assert(sequence->sequence);
    }

    sequence->sequence[sequence->sequence_used++] = signal_index;
}

static bool digital_sequence_setup_dma(DigitalSequence* sequence) {
    furi_assert(sequence);

    digital_signal_stop_dma();

    sequence->dma_config_gpio.MemoryOrM2MDstAddress = (uint32_t)sequence->gpio_buff;
    sequence->dma_config_gpio.PeriphOrM2MSrcAddress = (uint32_t) & (sequence->gpio->port->BSRR);

    /* set up DMA channel 1 and 2 for GPIO and timer copy operations */
    LL_DMA_Init(DMA1, LL_DMA_CHANNEL_1, &sequence->dma_config_gpio);
    LL_DMA_Init(DMA1, LL_DMA_CHANNEL_2, &sequence->dma_config_timer);

    /* enable both DMA channels */
    LL_DMA_EnableChannel(DMA1, LL_DMA_CHANNEL_1);
    LL_DMA_EnableChannel(DMA1, LL_DMA_CHANNEL_2);

    return true;
}

static DigitalSignal* digital_sequence_bake(DigitalSequence* sequence) {
    furi_assert(sequence);

    uint32_t edges = 0;

    for(uint32_t pos = 0; pos < sequence->sequence_used; pos++) {
        uint8_t signal_index = sequence->sequence[pos];
        DigitalSignal* sig = sequence->signals[signal_index];

        edges += sig->edge_cnt;
    }

    DigitalSignal* ret = digital_signal_alloc(edges);

    for(uint32_t pos = 0; pos < sequence->sequence_used; pos++) {
        uint8_t signal_index = sequence->sequence[pos];
        DigitalSignal* sig = sequence->signals[signal_index];

        digital_signal_append(ret, sig);
    }

    return ret;
}

static void digital_sequence_update_pos(DigitalSequence* sequence) {
    struct ReloadBuffer* dma_buffer = sequence->dma_buffer;

    dma_buffer->read_pos = dma_buffer->size - LL_DMA_GetDataLength(DMA1, LL_DMA_CHANNEL_2);
}

static const uint32_t wait_ms = 10;
static const uint32_t wait_ticks = wait_ms * 1000 * 64;

static void digital_sequence_finish(DigitalSequence* sequence) {
    struct ReloadBuffer* dma_buffer = sequence->dma_buffer;

    if(dma_buffer->dma_active) {
        uint32_t prev_timer = DWT->CYCCNT;
        uint32_t end_pos = (dma_buffer->write_pos + 1) % dma_buffer->size;
        do {
            uint32_t last_pos = dma_buffer->read_pos;

            digital_sequence_update_pos(sequence);

            /* we are finished, when the DMA transferred the 0xFFFFFFFF-timer which is the current write_pos */
            if(dma_buffer->read_pos == end_pos) {
                break;
            }

            if(last_pos != dma_buffer->read_pos) { //-V547
                prev_timer = DWT->CYCCNT;
            }
            if(DWT->CYCCNT - prev_timer > wait_ticks) {
                /*FURI_LOG_D(
                    TAG,
                    "[SEQ] hung %lu ms in finish (ARR 0x%08lx, read %lu, write %lu)",
                    wait_ms,
                    TIM2->ARR,
                    dma_buffer->read_pos,
                    dma_buffer->write_pos);*/
                break;
            }
        } while(1);
    }

    digital_signal_stop_timer();
    digital_signal_stop_dma();
}

static void digital_sequence_queue_pulse(DigitalSequence* sequence, uint32_t length) {
    struct ReloadBuffer* dma_buffer = sequence->dma_buffer;

    if(dma_buffer->dma_active) {
        uint32_t prev_timer = DWT->CYCCNT;
        uint32_t end_pos = (dma_buffer->write_pos + 1) % dma_buffer->size;
        do {
            uint32_t last_pos = dma_buffer->read_pos;
            digital_sequence_update_pos(sequence);

            if(dma_buffer->read_pos != end_pos) {
                break;
            }

            if(last_pos != dma_buffer->read_pos) { //-V547
                prev_timer = DWT->CYCCNT;
            }
            if(DWT->CYCCNT - prev_timer > wait_ticks) {
                /*FURI_LOG_D(
                    TAG,
                    "[SEQ] hung %lu ms in queue (ARR 0x%08lx, read %lu, write %lu)",
                    wait_ms,
                    TIM2->ARR,
                    dma_buffer->read_pos,
                    dma_buffer->write_pos);*/
                break;
            }
        } while(1);
    }

    dma_buffer->buffer[dma_buffer->write_pos] = length;
    dma_buffer->write_pos = (dma_buffer->write_pos + 1) % dma_buffer->size;
    dma_buffer->buffer[dma_buffer->write_pos] = 0xFFFFFFFF;
}

bool digital_sequence_send(DigitalSequence* sequence) {
    furi_assert(sequence);

    struct ReloadBuffer* dma_buffer = sequence->dma_buffer;

    furi_hal_gpio_init(sequence->gpio, GpioModeOutputPushPull, GpioPullNo, GpioSpeedVeryHigh);
#ifdef DEBUG_OUTPUT
    furi_hal_gpio_init(&DEBUG_OUTPUT, GpioModeOutputPushPull, GpioPullNo, GpioSpeedVeryHigh);
#endif

    if(sequence->bake) {
        DigitalSignal* sig = digital_sequence_bake(sequence);

        digital_signal_send(sig, sequence->gpio);
        digital_signal_free(sig);
        return true;
    }

    int32_t remainder = 0;
    bool traded_first = false;

    FURI_CRITICAL_ENTER();

    dma_buffer->dma_active = false;
    dma_buffer->buffer[0] = 0xFFFFFFFF;
    dma_buffer->read_pos = 0;
    dma_buffer->write_pos = 0;

    for(uint32_t seq_pos = 0; seq_pos < sequence->sequence_used; seq_pos++) {
        uint8_t signal_index = sequence->sequence[seq_pos];
        DigitalSignal* sig = sequence->signals[signal_index];
        bool last_signal = ((seq_pos + 1) == sequence->sequence_used);

        /* all signals are prepared and we can re-use the GPIO buffer from the fist signal */
        if(seq_pos == 0) {
            sequence->gpio_buff = sig->internals->gpio_buff;
        }

        for(uint32_t pulse_pos = 0; pulse_pos < sig->internals->reload_reg_entries; pulse_pos++) {
            if(traded_first) {
                traded_first = false;
                continue;
            }
            uint32_t pulse_length = 0;
            bool last_pulse = ((pulse_pos + 1) == sig->internals->reload_reg_entries);

            pulse_length = sig->reload_reg_buff[pulse_pos];

            /* when we are too late more than half a tick, make the first edge temporarily longer */
            if(remainder >= T_TIM_DIV2) {
                remainder -= T_TIM;
                pulse_length += 1;
            }
            remainder += sig->internals->reload_reg_remainder;

            /* last pulse in that signal and have a next signal? */
            if(last_pulse) {
                if((seq_pos + 1) < sequence->sequence_used) {
                    DigitalSignal* sig_next = sequence->signals[sequence->sequence[seq_pos + 1]];

                    /* when a signal ends with the same level as the next signal begins, let the fist signal generate the whole pulse */
                    /* beware, we do not want the level after the last edge, but the last level before that edge */
                    bool end_level = sig->start_level ^ ((sig->edge_cnt % 2) == 0);

                    /* take from the next, add it to the current if they have the same level */
                    if(end_level == sig_next->start_level) {
                        pulse_length += sig_next->reload_reg_buff[0];
                        traded_first = true;
                    }
                }
            }

            digital_sequence_queue_pulse(sequence, pulse_length);

            /* start transmission when buffer was filled enough */
            bool start_send = sequence->dma_buffer->write_pos >= (sequence->dma_buffer->size - 4);

            /* or it was the last pulse */
            if(last_pulse && last_signal) {
                start_send = true;
            }

            /* start transmission */
            if(start_send && !dma_buffer->dma_active) {
                digital_sequence_setup_dma(sequence);
                digital_signal_setup_timer();

                /* if the send time is specified, wait till the core timer passed beyond that time */
                if(sequence->send_time_active) {
                    sequence->send_time_active = false;
                    while(sequence->send_time - DWT->CYCCNT < 0x80000000) {
                    }
                }
                digital_signal_start_timer();
                dma_buffer->dma_active = true;
            }
        }
    }

    /* wait until last dma transaction was finished */
    digital_sequence_finish(sequence);
    FURI_CRITICAL_EXIT();

    return true;
}

void digital_sequence_clear(DigitalSequence* sequence) {
    furi_assert(sequence);

    sequence->sequence_used = 0;
}

void digital_sequence_timebase_correction(DigitalSequence* sequence, float factor) {
    for(uint32_t sig_pos = 0; sig_pos < sequence->signals_size; sig_pos++) {
        DigitalSignal* signal = sequence->signals[sig_pos];

        if(signal) {
            signal->internals->factor = (uint32_t)(1024 * 1024 * factor);
            digital_signal_prepare_arr(signal);
        }
    }
}