132 lines
4.3 KiB
Markdown
132 lines
4.3 KiB
Markdown
# FreeRTOS based AVR library for PCF8574(A) 8-bit I/O expander
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## Features
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1. Support of 16 expanders on one bus.
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2. Support of output and input GPIO's work mode.
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3. Support of interrupts from input GPIO's.
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## Note
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1. Enable interrupt support only if input GPIO's are used.
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2. All the INT GPIO's on the extenders must be connected to the one GPIO on AVR. Only PORTD4 - PORTD7 are acceptable!
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3. The input GPIO's are always pullup to the power supply.
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## Dependencies
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1. [zh_avr_free_rtos](http://git.zh.com.ru/avr_libraries/zh_avr_free_rtos)
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2. [zh_avr_vector](http://git.zh.com.ru/avr_libraries/zh_avr_vector)
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3. [zh_avr_common](http://git.zh.com.ru/avr_libraries/zh_avr_common)
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4. [zh_avr_i2c](http://git.zh.com.ru/avr_libraries/zh_avr_i2c)
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## Using
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In an existing project, run the following command to install the components:
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```text
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cd ../your_project/lib
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git clone http://git.zh.com.ru/avr_libraries/zh_avr_free_rtos
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git clone http://git.zh.com.ru/avr_libraries/zh_avr_vector
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git clone http://git.zh.com.ru/avr_libraries/zh_avr_i2c
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git clone http://git.zh.com.ru/avr_libraries/zh_avr_common
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git clone http://git.zh.com.ru/avr_libraries/zh_avr_pcf8574
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```
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In the application, add the component:
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```c
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#include "zh_avr_pcf8574.h"
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```
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## Examples
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One expander on bus. All GPIO's as output (except P0 - input). Interrupt is enable:
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```c
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#include "avr/io.h"
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#include "stdio.h"
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#include "zh_avr_pcf8574.h"
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#define BAUD_RATE 9600
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#define BAUD_PRESCALE (F_CPU / 16 / BAUD_RATE - 1)
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int usart(char byte, FILE *stream)
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{
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while ((UCSR0A & (1 << UDRE0)) == 0)
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{
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}
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UDR0 = byte;
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return 0;
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}
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FILE uart = FDEV_SETUP_STREAM(usart, NULL, _FDEV_SETUP_WRITE);
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zh_avr_pcf8574_handle_t pcf8574_handle = {0};
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void print_gpio_status(const char *message, uint8_t reg)
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{
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printf("%s", message);
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for (uint8_t i = 0; i < 8; ++i)
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{
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printf("%c", (reg & 0x80) ? '1' : '0');
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reg <<= 1;
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}
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printf(".\n");
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}
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void pcf8574_example_task(void *pvParameters)
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{
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zh_avr_i2c_master_init(false);
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zh_avr_pcf8574_init_config_t pcf8574_init_config = ZH_AVR_PCF8574_INIT_CONFIG_DEFAULT();
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pcf8574_init_config.i2c_address = 0x38;
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pcf8574_init_config.p0_gpio_work_mode = true; // Required only for input GPIO.
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pcf8574_init_config.interrupt_gpio = PORTD4; // Required only if used input GPIO interrupts.
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zh_avr_pcf8574_init(&pcf8574_init_config, &pcf8574_handle);
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uint8_t reg = 0;
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zh_avr_pcf8574_read(&pcf8574_handle, ®);
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print_gpio_status("GPIO status: ", reg);
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printf("Set P7 to 1, P1 to 1 and P0 to 0.\n");
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zh_avr_pcf8574_write(&pcf8574_handle, 0b10000010); // GPIO P0 will not be changed because it is operating in input mode.
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zh_avr_pcf8574_read(&pcf8574_handle, ®);
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print_gpio_status("GPIO status: ", reg);
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printf("Sets P0 to 0.\n");
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zh_avr_pcf8574_write_gpio(&pcf8574_handle, 0, false); // GPIO P0 will not be changed because it is operating in input mode.
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bool gpio = 0;
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zh_avr_pcf8574_read_gpio(&pcf8574_handle, 0, &gpio);
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printf("P0 status: %d.\n", gpio);
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printf("Set P1 to 0.\n");
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zh_avr_pcf8574_write_gpio(&pcf8574_handle, 1, false);
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zh_avr_pcf8574_read_gpio(&pcf8574_handle, 1, &gpio);
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printf("P1 status: %d.\n", gpio);
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zh_avr_pcf8574_read(&pcf8574_handle, ®);
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print_gpio_status("GPIO status: ", reg);
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printf("Reset all GPIO.\n");
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zh_avr_pcf8574_reset(&pcf8574_handle);
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zh_avr_pcf8574_read(&pcf8574_handle, ®);
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print_gpio_status("GPIO status: ", reg);
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printf("Task Remaining Stack Size %d.\n", uxTaskGetStackHighWaterMark(NULL));
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vTaskDelete(NULL);
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}
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int main(void)
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{
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UBRR0H = (BAUD_PRESCALE >> 8);
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UBRR0L = BAUD_PRESCALE;
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UCSR0B = (1 << RXEN0) | (1 << TXEN0);
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UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
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stdout = &uart;
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xTaskCreate(pcf8574_example_task, "pcf8574 example task", 124, NULL, tskIDLE_PRIORITY, NULL);
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vTaskStartScheduler();
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return 0;
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}
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void zh_avr_pcf8574_event_handler(zh_avr_pcf8574_event_on_isr_t *event) // Do not delete! Leave blank if interrupts are not used.
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{
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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);
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printf("Interrupt Task Remaining Stack Size %d.\n", uxTaskGetStackHighWaterMark(NULL));
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}
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ISR(PCINT2_vect) // Required only if used input GPIO interrupts.
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{
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zh_avr_pcf8574_isr_handler();
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}
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```
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