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 PORTD4 - PORTD7 are acceptable!
3. The input GPIO's are always pullup to the power supply.

Dependencies

1. zh_avr_free_rtos
2. zh_avr_vector
3. zh_avr_common
4. zh_avr_i2c

Using

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

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:

#include "zh_avr_pcf8574.h"

Examples

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

#include "avr/io.h"
#include "stdio.h"
#include "zh_avr_pcf8574.h"

#define BAUD_RATE 9600
#define BAUD_PRESCALE (F_CPU / 16 / BAUD_RATE - 1)

int usart(char byte, FILE *stream)
{
    while ((UCSR0A & (1 << UDRE0)) == 0)
    {
    }
    UDR0 = byte;
    return 0;
}
FILE uart = FDEV_SETUP_STREAM(usart, NULL, _FDEV_SETUP_WRITE);

zh_avr_pcf8574_handle_t pcf8574_handle = {0};

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 pcf8574_example_task(void *pvParameters)
{
    zh_avr_i2c_master_init(false);
    zh_avr_pcf8574_init_config_t pcf8574_init_config = ZH_AVR_PCF8574_INIT_CONFIG_DEFAULT();
    pcf8574_init_config.i2c_address = 0x38;
    pcf8574_init_config.p0_gpio_work_mode = true; // Required only for input GPIO.
    pcf8574_init_config.interrupt_gpio = PORTD4;  // Required only if used input GPIO interrupts.
    zh_avr_pcf8574_init(&pcf8574_init_config, &pcf8574_handle);
    uint8_t reg = 0;
    zh_avr_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_avr_pcf8574_write(&pcf8574_handle, 0b10000010); // GPIO P0 will not be changed because it is operating in input mode.
    zh_avr_pcf8574_read(&pcf8574_handle, &reg);
    print_gpio_status("GPIO status: ", reg);
    printf("Sets P0 to 0.\n");
    zh_avr_pcf8574_write_gpio(&pcf8574_handle, 0, false); // GPIO P0 will not be changed because it is operating in input mode.
    bool gpio = 0;
    zh_avr_pcf8574_read_gpio(&pcf8574_handle, 0, &gpio);
    printf("P0 status: %d.\n", gpio);
    printf("Set P1 to 0.\n");
    zh_avr_pcf8574_write_gpio(&pcf8574_handle, 1, false);
    zh_avr_pcf8574_read_gpio(&pcf8574_handle, 1, &gpio);
    printf("P1 status: %d.\n", gpio);
    zh_avr_pcf8574_read(&pcf8574_handle, &reg);
    print_gpio_status("GPIO status: ", reg);
    printf("Reset all GPIO.\n");
    zh_avr_pcf8574_reset(&pcf8574_handle);
    zh_avr_pcf8574_read(&pcf8574_handle, &reg);
    print_gpio_status("GPIO status: ", reg);
    printf("Task Remaining Stack Size %d.\n", uxTaskGetStackHighWaterMark(NULL));
    vTaskDelete(NULL);
}
int main(void)
{
    UBRR0H = (BAUD_PRESCALE >> 8);
    UBRR0L = BAUD_PRESCALE;
    UCSR0B = (1 << RXEN0) | (1 << TXEN0);
    UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
    stdout = &uart;
    xTaskCreate(pcf8574_example_task, "pcf8574 example task", 124, NULL, tskIDLE_PRIORITY, NULL);
    vTaskStartScheduler();
    return 0;
}

void zh_avr_pcf8574_event_handler(zh_avr_pcf8574_event_on_isr_t *event) // Required only if used input GPIO interrupts.
{
    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);
    printf("Interrupt Task Remaining Stack Size %d.\n", uxTaskGetStackHighWaterMark(NULL));
}

ISR(PCINT2_vect) // Required only if used input GPIO interrupts.
{
    zh_avr_pcf8574_isr_handler();
}