zh_pcf8574/README.md

ESP32 ESP-IDF component for PCF8574 8-bit I/O expander

Features

1. I2C communication via esp-idf i2c_master driver.
2. Configurable GPIO direction for each pin (P0-P7).
3. Interrupt handling with GPIO level detection.
4. Event-based architecture using esp_event framework.
5. Statistics tracking for debugging and monitoring.

Note

Enable the following settings in menuconfig:

GPIO_CTRL_FUNC_IN_IRAM
I2C_ISR_IRAM_SAFE
I2C_MASTER_ISR_HANDLER_IN_IRAM

Using

In an existing project, run the following command to install the components:

cd ../your_project/components
git clone https://github.com/aZholtikov/zh_pcf8574

In the application, add the component:

#include "zh_pcf8574.h"

Example

#include "zh_pcf8574.h"

#define I2C_PORT (I2C_NUM_MAX - 1)

zh_pcf8574_handle_t *pcf8574_handle = NULL;

void zh_pcf8574_event_handler(void *arg, esp_event_base_t event_base, int32_t event_id, void *event_data);

void print_gpio_status(const char *message, uint8_t reg)
{
    printf("%s", message);
    for (uint8_t i = 0; i < 8; ++i)
    {
        printf("%c", (reg & 0x80) ? '1' : '0');
        reg <<= 1;
    }
    printf(".\n");
}

void app_main(void)
{
    esp_log_level_set("zh_pcf8574", ESP_LOG_ERROR);
    esp_log_level_set("zh_vector", ESP_LOG_ERROR);
    i2c_master_bus_config_t i2c_bus_config = {
        .clk_source = I2C_CLK_SRC_DEFAULT,
        .i2c_port = I2C_PORT,
        .scl_io_num = GPIO_NUM_22,
        .sda_io_num = GPIO_NUM_21,
        .glitch_ignore_cnt = 7,
        .flags.enable_internal_pullup = true,
    };
    i2c_master_bus_handle_t i2c_bus_handle = NULL;
    i2c_new_master_bus(&i2c_bus_config, &i2c_bus_handle);
    esp_event_loop_create_default();
    esp_event_handler_instance_register(ZH_PCF8574, ESP_EVENT_ANY_ID, &zh_pcf8574_event_handler, NULL, NULL);
    zh_pcf8574_init_config_t config = ZH_PCF8574_INIT_CONFIG_DEFAULT();
    config.i2c_handle = i2c_bus_handle;
    config.i2c_address = 0x38;
    config.p0_gpio_work_mode = ZH_PCF8574_GPIO_INPUT;
    config.interrupt_gpio = GPIO_NUM_14;
    zh_pcf8574_init(&config, &pcf8574_handle);
    uint8_t reg = 0;
    zh_pcf8574_read(&pcf8574_handle, &reg);
    print_gpio_status("GPIO status: ", reg);
    printf("Set P7 to 1, P1 to 1 and P0 to 0.\n");
    zh_pcf8574_write(&pcf8574_handle, 0b10000010);
    zh_pcf8574_read(&pcf8574_handle, &reg);
    print_gpio_status("GPIO status: ", reg);
    printf("Sets P0 to 0.\n");
    zh_pcf8574_write_gpio(&pcf8574_handle, ZH_PCF8574_GPIO_NUM_P0, ZH_PCF8574_GPIO_LOW);
    bool gpio = 0;
    zh_pcf8574_read_gpio(&pcf8574_handle, ZH_PCF8574_GPIO_NUM_P0, &gpio);
    printf("P0 status: %d.\n", gpio);
    printf("Set P4 to 1.\n");
    zh_pcf8574_write_gpio(&pcf8574_handle, ZH_PCF8574_GPIO_NUM_P4, ZH_PCF8574_GPIO_HIGH);
    zh_pcf8574_read_gpio(&pcf8574_handle, ZH_PCF8574_GPIO_NUM_P4, &gpio);
    printf("P4 status: %d.\n", gpio);
    zh_pcf8574_read(&pcf8574_handle, &reg);
    print_gpio_status("GPIO status: ", reg);
    printf("Reset all GPIO.\n");
    zh_pcf8574_reset(&pcf8574_handle);
    zh_pcf8574_read(&pcf8574_handle, &reg);
    print_gpio_status("GPIO status: ", reg);
    for (;;)
    {
        const zh_pcf8574_stats_t *stats = zh_pcf8574_get_stats();
        printf("Number of i2c driver error: %ld.\n", stats->i2c_driver_error);
        printf("Number of event post error: %ld.\n", stats->event_post_error);
        printf("Number of vector error: %ld.\n", stats->vector_error);
        printf("Number of queue overflow error: %ld.\n", stats->queue_overflow_error);
        printf("Minimum free stack size: %ld.\n", stats->min_stack_size);
        vTaskDelay(60000 / portTICK_PERIOD_MS);
    }
}

void zh_pcf8574_event_handler(void *arg, esp_event_base_t event_base, int32_t event_id, void *event_data)
{
    zh_pcf8574_event_on_isr_t *event = event_data;
    printf("Interrupt happened on device address 0x%02X on GPIO number %d at level %d at time %lld.\n", event->i2c_address, event->gpio_number, event->gpio_level, event->interrupt_time);
}