esp8266-clock/main/tm1637.c

/*
 * SPDX-FileCopyrightText: 2022 Helmut Pozimski <helmut@pozimski.eu>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 */

#include <stdint.h>
#include <driver/gpio.h>

#include "tm1637.h"

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

#define DATA_COMMAND 0x40
#define DISPLAY_ON_COMMAND 0x88
#define DISPLAY_OFF_COMMAND 0x80
#define ADDRESS_COMMAND 0xC0

static void delay() {
    vTaskDelay(1 / portTICK_PERIOD_MS);
}

esp_err_t tm1637_init(tm1637_config *config, uint8_t clk_pin, uint8_t dio_pin, bool show_colon, uint8_t brightness) {
    gpio_config_t io_conf;
    esp_err_t ret;
    io_conf.intr_type = GPIO_INTR_DISABLE;
    io_conf.mode = GPIO_MODE_OUTPUT;
    io_conf.pin_bit_mask = ((1ULL << clk_pin)) | ((1ULL << dio_pin));
    io_conf.pull_down_en = 0;
    io_conf.pull_up_en = 0;
    ret = gpio_config(&io_conf);
    config->clk_pin = clk_pin;
    config->dio_pin = dio_pin;
    config->show_colon = show_colon;
    config->brightness = brightness;
    gpio_set_level(dio_pin, 1);
    gpio_set_level(clk_pin, 1);
    delay();
    return ret;
}

static void start_transfer(tm1637_config *config) {
    gpio_set_level(config->dio_pin, 0);
    delay();
}

static void stop_transfer(tm1637_config *config) {
    gpio_set_level(config->dio_pin, 0);
    delay();
    gpio_set_level(config->clk_pin, 1);
    delay();
    gpio_set_level(config->dio_pin, 1);
    delay();
}

static void write_byte(tm1637_config *config, uint8_t byte) {
    uint8_t data = byte;

    for (uint8_t i = 0; i < 8; i++) {
        gpio_set_level(config->clk_pin, 0);
        delay();
        gpio_set_level(config->dio_pin, data & 0x01);
        delay();
        gpio_set_level(config->clk_pin, 1);
        delay();
        data = data >> 1;
    }

    gpio_set_level(config->clk_pin, 0);
    delay();
    gpio_set_level(config->dio_pin, 1);
    delay();
    gpio_set_level(config->clk_pin, 1);

    delay();

    gpio_set_direction(config->dio_pin, GPIO_MODE_INPUT);

    delay();

    int result = -1;

    while (result != 0) {
        result = gpio_get_level(config->dio_pin);
    }

    delay();
    gpio_set_level(config->clk_pin, 0);
    delay();
    gpio_set_direction(config->dio_pin, GPIO_MODE_OUTPUT);
    delay();
}

void tm1637_set_segment(tm1637_config *config, uint8_t value, uint8_t segment, bool enable_display) {
    uint16_t write_value = NUMERALS[value];
    if (config->show_colon) {
        write_value |= 0x80;
    }
    start_transfer(config);
    write_byte(config, DATA_COMMAND);
    stop_transfer(config);

    start_transfer(config);
    write_byte(config, ADDRESS_COMMAND | segment);

    write_byte(config, write_value);
    stop_transfer(config);

    start_transfer(config);
    if (enable_display) {
        write_byte(config, DISPLAY_ON_COMMAND | (config->brightness & 0x07));
    } else {
        write_byte(config, DISPLAY_OFF_COMMAND | (config->brightness & 0x07));
    }
    stop_transfer(config);
}