# FreeRTOS based AVR library for PCF8574(A) 8-bit I/O expander

## Features

1. Support of 16 expanders on one bus.
2. Support of output and input GPIO's work mode.
3. Support of interrupts from input GPIO's.

## Note

1. Enable interrupt support only if input GPIO's are used.
2. All the INT GPIO's on the extenders must be connected to the one GPIO on AVR. Only PORTD3 - PORTD7 are acceptable!
3. The input GPIO's are always pullup to the power supply.

## Dependencies

1. [zh_avr_free_rtos](http://git.zh.com.ru/avr_libraries/zh_avr_free_rtos)
2. [zh_avr_vector](http://git.zh.com.ru/avr_libraries/zh_avr_vector)
3. [zh_avr_common](http://git.zh.com.ru/avr_libraries/zh_avr_common)
4. [zh_avr_i2c](http://git.zh.com.ru/avr_libraries/zh_avr_i2c)

## Using

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

```text
cd ../your_project/lib
git clone http://git.zh.com.ru/avr_libraries/zh_avr_free_rtos
git clone http://git.zh.com.ru/avr_libraries/zh_avr_vector
git clone http://git.zh.com.ru/avr_libraries/zh_avr_i2c
git clone http://git.zh.com.ru/avr_libraries/zh_avr_common
git clone http://git.zh.com.ru/avr_libraries/zh_avr_pcf8574
```

In the application, add the component:

```c
#include "zh_avr_pcf8574.h"
```

## Examples

One expander on bus. All GPIO's as output (except P0 - input). Interrupt is enable:

```c
#include "zh_avr_pcf8574.h"

#define I2C_PORT (I2C_NUM_MAX - 1)

#ifndef CONFIG_IDF_TARGET_ESP8266
i2c_master_bus_handle_t i2c_bus_handle = NULL;
#endif

zh_pcf8574_handle_t pcf8574_handle = {0};

void zh_pcf8574_event_handler(void *arg, esp_event_base_t event_base, int32_t event_id, void *event_data); // Required only if used input GPIO interrupts.

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_NONE); // For ESP8266 first enable "Component config -> Log output -> Enable log set level" via menuconfig.
    esp_log_level_set("zh_vector", ESP_LOG_NONE);  // For ESP8266 first enable "Component config -> Log output -> Enable log set level" via menuconfig.
#ifdef CONFIG_IDF_TARGET_ESP8266
    i2c_config_t i2c_config = {
        .mode = I2C_MODE_MASTER,
        .sda_io_num = GPIO_NUM_4, // In accordance with used chip.
        .sda_pullup_en = GPIO_PULLUP_ENABLE,
        .scl_io_num = GPIO_NUM_5, // In accordance with used chip.
        .scl_pullup_en = GPIO_PULLUP_ENABLE,
    };
    i2c_driver_install(I2C_PORT, i2c_config.mode);
    i2c_param_config(I2C_PORT, &i2c_config);
#else
    i2c_master_bus_config_t i2c_bus_config = {
        .clk_source = I2C_CLK_SRC_DEFAULT,
        .i2c_port = I2C_PORT,
        .scl_io_num = GPIO_NUM_22, // In accordance with used chip.
        .sda_io_num = GPIO_NUM_21, // In accordance with used chip.
        .glitch_ignore_cnt = 7,
        .flags.enable_internal_pullup = true,
    };
    i2c_new_master_bus(&i2c_bus_config, &i2c_bus_handle);
#endif
    esp_event_loop_create_default(); // Required only if used input GPIO interrupts.
#ifdef CONFIG_IDF_TARGET_ESP8266
    esp_event_handler_register(ZH_PCF8574, ESP_EVENT_ANY_ID, &zh_pcf8574_event_handler, NULL); // Required only if used input GPIO interrupts.
#else
    esp_event_handler_instance_register(ZH_PCF8574, ESP_EVENT_ANY_ID, &zh_pcf8574_event_handler, NULL, NULL); // Required only if used input GPIO interrupts.
#endif
    zh_pcf8574_init_config_t pcf8574_init_config = ZH_PCF8574_INIT_CONFIG_DEFAULT();
#ifdef CONFIG_IDF_TARGET_ESP8266
    pcf8574_init_config.i2c_port = I2C_PORT;
#else
    pcf8574_init_config.i2c_handle = i2c_bus_handle;
#endif
    pcf8574_init_config.i2c_address = 0x38;
    pcf8574_init_config.p0_gpio_work_mode = true;     // Required only for input GPIO.
    pcf8574_init_config.interrupt_gpio = GPIO_NUM_14; // Required only if used input GPIO interrupts.
    zh_pcf8574_init(&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); // GPIO P0 will not be changed because it is operating in input mode.
    zh_pcf8574_read(&pcf8574_handle, &reg);
    print_gpio_status("GPIO status: ", reg);
    printf("Sets P0 to 0.\n");
    zh_pcf8574_write_gpio(&pcf8574_handle, 0, false); // GPIO P0 will not be changed because it is operating in input mode.
    bool gpio = 0;
    zh_pcf8574_read_gpio(&pcf8574_handle, 0, &gpio);
    printf("P0 status: %d.\n", gpio);
    printf("Set P1 to 0.\n");
    zh_pcf8574_write_gpio(&pcf8574_handle, 1, false);
    zh_pcf8574_read_gpio(&pcf8574_handle, 1, &gpio);
    printf("P1 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);
}

void zh_pcf8574_event_handler(void *arg, esp_event_base_t event_base, int32_t event_id, void *event_data) // Required only if used input GPIO interrupts.
{
    zh_pcf8574_event_on_isr_t *event = event_data;
    printf("Interrupt happened on device address 0x%02X on GPIO number %d at level %d.\n", event->i2c_address, event->gpio_number, event->gpio_level);
}
```