ESP32 ESP-IDF component for PCF8574 8-bit I/O expander
Features
- I2C communication via the ESP-IDF I2C master driver.
- Configurable GPIO direction for each pin P0 through P7.
- Interrupt handling with GPIO level detection and event notification.
- Event-based architecture using the esp_event framework.
- Statistics tracking for debugging and monitoring.
- Multiple device instances on a single I2C bus.
Attention
- Requires ESP-IDF v5.0 or later with the I2C master driver.
- Interrupt handling runs in task context and is not IRAM-safe.
- A single interrupt GPIO pin is shared by all initialized devices.
- The internal task is deleted only when the last device instance is deinitialized.
Using
In an existing project, run the following command to install the component:
cd ../your_project/components
git clone https://github.com/aZholtikov/zh_pcf8574
In the application, add the component:
#include "zh_pcf8574.h"
Examples
Basic Example
#include "zh_pcf8574.h"
#define I2C_PORT (I2C_NUM_MAX - 1)
zh_pcf8574_handle_t *pcf8574_handle = NULL;
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);
zh_pcf8574_init_config_t config = ZH_PCF8574_INIT_CONFIG_DEFAULT();
config.i2c_handle = i2c_bus_handle;
config.i2c_address = 0x38;
esp_err_t ret = zh_pcf8574_init(&config, &pcf8574_handle);
if (ret != ESP_OK)
{
printf("PCF8574 initialization error: %s\n", esp_err_to_name(ret));
return;
}
uint8_t reg = 0;
ret = zh_pcf8574_read(&pcf8574_handle, ®);
if (ret == ESP_OK)
{
printf("GPIO status: 0x%02X\n", reg);
}
ret = zh_pcf8574_write(&pcf8574_handle, 0b10000010);
if (ret == ESP_OK)
{
printf("Write OK\n");
}
ret = zh_pcf8574_read(&pcf8574_handle, ®);
if (ret == ESP_OK)
{
printf("GPIO status after write: 0x%02X\n", reg);
}
ret = zh_pcf8574_deinit(&pcf8574_handle);
if (ret == ESP_OK)
{
printf("Deinit OK\n");
}
}
GPIO Example
#include "zh_pcf8574.h"
#define I2C_PORT (I2C_NUM_MAX - 1)
zh_pcf8574_handle_t *pcf8574_handle = NULL;
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);
zh_pcf8574_init_config_t config = ZH_PCF8574_INIT_CONFIG_DEFAULT();
config.i2c_handle = i2c_bus_handle;
config.i2c_address = 0x38;
esp_err_t ret = zh_pcf8574_init(&config, &pcf8574_handle);
if (ret != ESP_OK)
{
printf("PCF8574 initialization error: %s\n", esp_err_to_name(ret));
return;
}
ret = zh_pcf8574_write_gpio(&pcf8574_handle, ZH_PCF8574_GPIO_NUM_P4, ZH_PCF8574_GPIO_HIGH);
if (ret == ESP_OK)
{
printf("P4 set high\n");
}
bool status = false;
ret = zh_pcf8574_read_gpio(&pcf8574_handle, ZH_PCF8574_GPIO_NUM_P4, &status);
if (ret == ESP_OK)
{
printf("P4 status: %d\n", status);
}
ret = zh_pcf8574_write_gpio(&pcf8574_handle, ZH_PCF8574_GPIO_NUM_P4, ZH_PCF8574_GPIO_LOW);
if (ret == ESP_OK)
{
printf("P4 set low\n");
}
ret = zh_pcf8574_read_gpio(&pcf8574_handle, ZH_PCF8574_GPIO_NUM_P4, &status);
if (ret == ESP_OK)
{
printf("P4 status: %d\n", status);
}
zh_pcf8574_deinit(&pcf8574_handle);
}
Reset Example
#include "zh_pcf8574.h"
#define I2C_PORT (I2C_NUM_MAX - 1)
zh_pcf8574_handle_t *pcf8574_handle = NULL;
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);
zh_pcf8574_init_config_t config = ZH_PCF8574_INIT_CONFIG_DEFAULT();
config.i2c_handle = i2c_bus_handle;
config.i2c_address = 0x38;
esp_err_t ret = zh_pcf8574_init(&config, &pcf8574_handle);
if (ret != ESP_OK)
{
printf("PCF8574 initialization error: %s\n", esp_err_to_name(ret));
return;
}
zh_pcf8574_write(&pcf8574_handle, 0xFF);
uint8_t reg = 0;
ret = zh_pcf8574_read(&pcf8574_handle, ®);
if (ret == ESP_OK)
{
printf("GPIO before reset: 0x%02X\n", reg);
}
ret = zh_pcf8574_reset(&pcf8574_handle);
if (ret == ESP_OK)
{
printf("Reset OK\n");
}
ret = zh_pcf8574_read(&pcf8574_handle, ®);
if (ret == ESP_OK)
{
printf("GPIO after reset: 0x%02X\n", reg);
}
zh_pcf8574_deinit(&pcf8574_handle);
}
Interrupt 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)
{
zh_pcf8574_event_on_isr_t *event = event_data;
printf("Interrupt on address 0x%02X pin P%d level %d time %lld\n",
event->i2c_address, event->gpio_number, event->gpio_level, event->interrupt_time);
}
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;
esp_err_t ret = zh_pcf8574_init(&config, &pcf8574_handle);
if (ret != ESP_OK)
{
printf("PCF8574 initialization error: %s\n", esp_err_to_name(ret));
return;
}
for (;;)
{
vTaskDelay(1000 / portTICK_PERIOD_MS);
}
}
Stats Example
#include "zh_pcf8574.h"
#define I2C_PORT (I2C_NUM_MAX - 1)
zh_pcf8574_handle_t *pcf8574_handle = NULL;
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);
zh_pcf8574_init_config_t config = ZH_PCF8574_INIT_CONFIG_DEFAULT();
config.i2c_handle = i2c_bus_handle;
config.i2c_address = 0x38;
esp_err_t ret = zh_pcf8574_init(&config, &pcf8574_handle);
if (ret != ESP_OK)
{
printf("PCF8574 initialization error: %s\n", esp_err_to_name(ret));
return;
}
uint8_t reg = 0;
zh_pcf8574_read(&pcf8574_handle, ®);
zh_pcf8574_write(&pcf8574_handle, 0xAA);
zh_pcf8574_read(&pcf8574_handle, ®);
const zh_pcf8574_stats_t *stats = zh_pcf8574_get_stats();
printf("I2C driver errors: %ld\n", stats->i2c_driver_error);
printf("Event post errors: %ld\n", stats->event_post_error);
printf("Vector errors: %ld\n", stats->vector_error);
printf("Queue overflow errors: %ld\n", stats->queue_overflow_error);
printf("Min free stack size: %ld\n", stats->min_stack_size);
zh_pcf8574_reset_stats();
stats = zh_pcf8574_get_stats();
printf("After reset I2C driver errors: %ld\n", stats->i2c_driver_error);
zh_pcf8574_deinit(&pcf8574_handle);
}