# AT32F403A/407 MCU Documentation Repository

## Introduction

This project provides comprehensive technical documentation and firmware driver resources for the Artery AT32F403A/407 ARM Cortex-M4 microcontroller series, designed as a primary reference source for Context7 and embedded systems development. The repository includes 26 detailed peripheral documentation files covering all major subsystems (CAN, Flash, PWC, ADC, I2C, SPI, TMR, USART, USB, GPIO, DMA, EMAC, and more), a complete firmware library v2.2.1 with peripheral drivers and CMSIS support, and an intelligent taxonomy system with 5 YAML files for semantic search. Each peripheral guide provides complete API references, initialization code examples, GPIO pin mappings, best practices, and troubleshooting guidance, making this a comprehensive resource for firmware development and Context7 AI integration.

The repository serves as both a critical reference for production firmware development and a Context7-optimized knowledge source with structured metadata and searchable content. With 26 peripheral documentation files totaling over 25,000 lines of technical content, complete peripheral driver implementations (26 headers + 25 source files), CMSIS ARM Cortex-M4 core support, and 5 YAML taxonomy files for intelligent search, developers have immediate access to working code examples and comprehensive API documentation. The markdown format ensures GitHub-native rendering with interactive tables, code syntax highlighting, cross-references, and full-text search across all technical documentation. For device errata and silicon limitations, users should download the official ES0002 errata sheet from Artery Technology's website, which documents 41 known issues with detailed workarounds for critical areas like Flash operations, CAN communication, and power management.

## API Reference and Code Examples

### CAN Controller Initialization

Initialize CAN controller with proper baudrate configuration and filter setup

```c
#include "at32f403a_407_can.h"

void can_configuration(void)
{
    can_base_type can_base_struct;
    can_baudrate_type can_baudrate_struct;
    can_filter_init_type can_filter_init_struct;

    // Enable CAN1 and GPIO clocks
    crm_periph_clock_enable(CRM_CAN1_PERIPH_CLOCK, TRUE);
    crm_periph_clock_enable(CRM_GPIOA_PERIPH_CLOCK, TRUE);

    // Configure GPIO pins (PA11=RX, PA12=TX)
    gpio_init_type gpio_init_struct;
    gpio_default_para_init(&gpio_init_struct);
    gpio_init_struct.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
    gpio_init_struct.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
    gpio_init_struct.gpio_mode = GPIO_MODE_MUX;
    gpio_init_struct.gpio_pins = GPIO_PINS_11 | GPIO_PINS_12;
    gpio_init_struct.gpio_pull = GPIO_PULL_NONE;
    gpio_init(GPIOA, &gpio_init_struct);

    // CAN base configuration
    can_default_para_init(&can_base_struct);
    can_base_struct.mode_selection = CAN_MODE_COMMUNICATE;
    can_base_struct.ttc_enable = FALSE;
    can_base_struct.aebo_enable = TRUE;
    can_base_struct.aed_enable = TRUE;
    can_base_struct.prsf_enable = FALSE;
    can_base_struct.mdrsel_selection = CAN_DISCARDING_FIRST_RECEIVED;
    can_base_struct.mmssr_enable = TRUE;
    can_base_init(CAN1, &can_base_struct);

    // Baudrate configuration for 500 kbps (assuming APB1 = 120 MHz)
    can_baudrate_struct.baudrate_div = 20;
    can_baudrate_struct.rsaw_size = CAN_RSAW_3TQ;
    can_baudrate_struct.bts1_size = CAN_BTS1_8TQ;
    can_baudrate_struct.bts2_size = CAN_BTS2_3TQ;
    can_baudrate_set(CAN1, &can_baudrate_struct);

    // Configure filter to accept all messages
    can_filter_init_struct.filter_activate_enable = TRUE;
    can_filter_init_struct.filter_mode = CAN_FILTER_MODE_ID_MASK;
    can_filter_init_struct.filter_fifo = CAN_FILTER_FIFO0;
    can_filter_init_struct.filter_number = 0;
    can_filter_init_struct.filter_bit = CAN_FILTER_32BIT;
    can_filter_init_struct.filter_id_high = 0x0000;
    can_filter_init_struct.filter_id_low = 0x0000;
    can_filter_init_struct.filter_mask_high = 0x0000;
    can_filter_init_struct.filter_mask_low = 0x0000;
    can_filter_init(CAN1, &can_filter_init_struct);
}
```

### CAN Message Transmission

Transmit CAN message with standard 11-bit identifier

```c
void can_transmit_message(uint32_t std_id, uint8_t *data, uint8_t length)
{
    can_tx_message_type tx_message;

    tx_message.standard_id = std_id;
    tx_message.extended_id = 0;
    tx_message.id_type = CAN_ID_STANDARD;
    tx_message.frame_type = CAN_TFT_DATA;
    tx_message.dlc = length;

    for(uint8_t i = 0; i < length; i++)
    {
        tx_message.data[i] = data[i];
    }

    can_message_transmit(CAN1, &tx_message);
}
```

### CAN Message Reception with Interrupt

Configure CAN reception interrupt and handler

```c
void can_nvic_configuration(void)
{
    nvic_irq_enable(CAN1_RX0_IRQn, 0, 0);
    can_interrupt_enable(CAN1, CAN_RF0MIEN_INT, TRUE);
}

void CAN1_RX0_IRQHandler(void)
{
    can_rx_message_type rx_message;

    if(can_flag_get(CAN1, CAN_RF0MN_FLAG) != RESET)
    {
        can_message_receive(CAN1, CAN_RX_FIFO0, &rx_message);

        // Process received message
        if(rx_message.frame_type == CAN_TFT_DATA)
        {
            process_can_data(rx_message.standard_id,
                           rx_message.data,
                           rx_message.dlc);
        }
    }
}
```

### Flash Memory Programming

Program flash memory with proper unlock/lock sequence

```c
#include "at32f403a_407_flash.h"

flash_status_type flash_write_data(uint32_t address, uint32_t *data, uint32_t length)
{
    flash_status_type status = FLASH_OPERATE_DONE;
    uint32_t i;

    // Unlock flash
    flash_unlock();

    // Write data word by word
    for(i = 0; i < length; i++)
    {
        status = flash_word_program(address + (i * 4), data[i]);
        if(status != FLASH_OPERATE_DONE)
        {
            break;
        }
    }

    // Lock flash
    flash_lock();

    return status;
}
```

### Flash Sector Erase

Erase a flash sector before programming

```c
flash_status_type flash_erase_sector(uint32_t sector_address)
{
    flash_status_type status;

    // Unlock flash
    flash_unlock();

    // Erase sector
    status = flash_sector_erase(sector_address);

    // Wait for operation to complete
    status = flash_operation_wait_for(ERASE_TIMEOUT);

    // Lock flash
    flash_lock();

    return status;
}
```

### ADC Single Channel Conversion

Initialize ADC for single channel conversion

```c
#include "at32f403a_407_adc.h"

void adc_single_channel_init(void)
{
    adc_base_config_type adc_base_struct;

    // Enable ADC and GPIO clocks
    crm_periph_clock_enable(CRM_ADC1_PERIPH_CLOCK, TRUE);
    crm_periph_clock_enable(CRM_GPIOA_PERIPH_CLOCK, TRUE);

    // Configure ADC clock (max 14 MHz for 12-bit mode)
    crm_adc_clock_div_set(CRM_ADC_DIV_6);

    // Configure GPIO pin as analog input (PA0)
    gpio_init_type gpio_init_struct;
    gpio_default_para_init(&gpio_init_struct);
    gpio_init_struct.gpio_pins = GPIO_PINS_0;
    gpio_init_struct.gpio_mode = GPIO_MODE_ANALOG;
    gpio_init(GPIOA, &gpio_init_struct);

    // ADC base configuration
    adc_base_default_para_init(&adc_base_struct);
    adc_base_struct.sequence_mode = FALSE;
    adc_base_struct.repeat_mode = FALSE;
    adc_base_struct.data_align = ADC_RIGHT_ALIGNMENT;
    adc_base_struct.ordinary_channel_length = 1;
    adc_base_config(ADC1, &adc_base_struct);

    // Configure channel
    adc_ordinary_channel_set(ADC1, ADC_CHANNEL_0, 1, ADC_SAMPLETIME_239_5);

    // Enable ADC
    adc_enable(ADC1, TRUE);

    // Calibrate ADC
    adc_calibration_init(ADC1);
    while(adc_calibration_init_status_get(ADC1));
    adc_calibration_start(ADC1);
    while(adc_calibration_status_get(ADC1));
}

uint16_t adc_read_channel(void)
{
    // Start conversion
    adc_ordinary_software_trigger_enable(ADC1, TRUE);

    // Wait for conversion to complete
    while(adc_flag_get(ADC1, ADC_OCCE_FLAG) == RESET);

    // Return conversion result
    return adc_ordinary_conversion_data_get(ADC1);
}
```

### ADC DMA Mode Configuration

Configure ADC with DMA for continuous conversion

```c
void adc_dma_mode_init(uint16_t *adc_buffer, uint32_t buffer_size)
{
    adc_base_config_type adc_base_struct;
    dma_init_type dma_init_struct;

    // Enable clocks
    crm_periph_clock_enable(CRM_DMA1_PERIPH_CLOCK, TRUE);
    crm_periph_clock_enable(CRM_ADC1_PERIPH_CLOCK, TRUE);

    // Configure DMA
    dma_reset(DMA1_CHANNEL1);
    dma_default_para_init(&dma_init_struct);
    dma_init_struct.buffer_size = buffer_size;
    dma_init_struct.direction = DMA_DIR_PERIPHERAL_TO_MEMORY;
    dma_init_struct.memory_base_addr = (uint32_t)adc_buffer;
    dma_init_struct.memory_data_width = DMA_MEMORY_DATA_WIDTH_HALFWORD;
    dma_init_struct.memory_inc_enable = TRUE;
    dma_init_struct.peripheral_base_addr = (uint32_t)&(ADC1->odt);
    dma_init_struct.peripheral_data_width = DMA_PERIPHERAL_DATA_WIDTH_HALFWORD;
    dma_init_struct.peripheral_inc_enable = FALSE;
    dma_init_struct.priority = DMA_PRIORITY_HIGH;
    dma_init_struct.loop_mode_enable = TRUE;
    dma_init(DMA1_CHANNEL1, &dma_init_struct);
    dma_channel_enable(DMA1_CHANNEL1, TRUE);

    // Configure ADC
    adc_base_default_para_init(&adc_base_struct);
    adc_base_struct.sequence_mode = FALSE;
    adc_base_struct.repeat_mode = TRUE;
    adc_base_struct.data_align = ADC_RIGHT_ALIGNMENT;
    adc_base_struct.ordinary_channel_length = 1;
    adc_base_config(ADC1, &adc_base_struct);

    adc_ordinary_channel_set(ADC1, ADC_CHANNEL_0, 1, ADC_SAMPLETIME_239_5);
    adc_dma_mode_enable(ADC1, TRUE);
    adc_enable(ADC1, TRUE);

    // Calibrate
    adc_calibration_init(ADC1);
    while(adc_calibration_init_status_get(ADC1));
    adc_calibration_start(ADC1);
    while(adc_calibration_status_get(ADC1));

    // Start conversion
    adc_ordinary_software_trigger_enable(ADC1, TRUE);
}
```

### I2C Master Transmit

Send data via I2C as master device

```c
#include "at32f403a_407_i2c.h"

void i2c_master_init(void)
{
    i2c_init_type i2c_init_struct;
    gpio_init_type gpio_init_struct;

    // Enable clocks
    crm_periph_clock_enable(CRM_I2C1_PERIPH_CLOCK, TRUE);
    crm_periph_clock_enable(CRM_GPIOB_PERIPH_CLOCK, TRUE);

    // Configure GPIO (PB6=SCL, PB7=SDA)
    gpio_default_para_init(&gpio_init_struct);
    gpio_init_struct.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
    gpio_init_struct.gpio_out_type = GPIO_OUTPUT_OPEN_DRAIN;
    gpio_init_struct.gpio_mode = GPIO_MODE_MUX;
    gpio_init_struct.gpio_pins = GPIO_PINS_6 | GPIO_PINS_7;
    gpio_init_struct.gpio_pull = GPIO_PULL_UP;
    gpio_init(GPIOB, &gpio_init_struct);

    // I2C configuration
    i2c_init_struct.i2c_mode = I2C_MODE_I2CMODE;
    i2c_init_struct.speed = I2C_SPEED_FAST;
    i2c_init_struct.duty_cycle = I2C_DUTYCYCLE_2;
    i2c_init_struct.own_address1 = 0x00;
    i2c_init_struct.ack_enable = I2C_ACK_ENABLE;
    i2c_init_struct.address_mode = I2C_ADDRESS_MODE_7BIT;
    i2c_init(I2C1, &i2c_init_struct);

    i2c_enable(I2C1, TRUE);
}

void i2c_master_transmit(uint8_t slave_addr, uint8_t *data, uint16_t length)
{
    uint16_t i;

    // Generate start condition
    i2c_start_generate(I2C1, TRUE);
    while(!i2c_flag_get(I2C1, I2C_STARTF_FLAG));

    // Send slave address
    i2c_7bit_address_send(I2C1, slave_addr, I2C_DIRECTION_TRANSMIT);
    while(!i2c_flag_get(I2C1, I2C_ADDRF_FLAG));
    i2c_flag_clear(I2C1, I2C_ADDRF_FLAG);

    // Transmit data
    for(i = 0; i < length; i++)
    {
        i2c_data_send(I2C1, data[i]);
        while(!i2c_flag_get(I2C1, I2C_TDBE_FLAG));
    }

    // Generate stop condition
    i2c_stop_generate(I2C1, TRUE);
}
```

### SPI Master Configuration

Initialize SPI as master device

```c
#include "at32f403a_407_spi.h"

void spi_master_init(void)
{
    spi_init_type spi_init_struct;
    gpio_init_type gpio_init_struct;

    // Enable clocks
    crm_periph_clock_enable(CRM_SPI1_PERIPH_CLOCK, TRUE);
    crm_periph_clock_enable(CRM_GPIOA_PERIPH_CLOCK, TRUE);

    // Configure GPIO (PA5=SCK, PA6=MISO, PA7=MOSI)
    gpio_default_para_init(&gpio_init_struct);
    gpio_init_struct.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
    gpio_init_struct.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
    gpio_init_struct.gpio_mode = GPIO_MODE_MUX;
    gpio_init_struct.gpio_pins = GPIO_PINS_5 | GPIO_PINS_7;
    gpio_init_struct.gpio_pull = GPIO_PULL_NONE;
    gpio_init(GPIOA, &gpio_init_struct);

    gpio_init_struct.gpio_pins = GPIO_PINS_6;
    gpio_init(GPIOA, &gpio_init_struct);

    // SPI configuration
    spi_default_para_init(&spi_init_struct);
    spi_init_struct.transmission_mode = SPI_TRANSMIT_FULL_DUPLEX;
    spi_init_struct.master_slave_mode = SPI_MODE_MASTER;
    spi_init_struct.mclk_freq_division = SPI_MCLK_DIV_8;
    spi_init_struct.first_bit_transmission = SPI_FIRST_BIT_MSB;
    spi_init_struct.frame_bit_num = SPI_FRAME_8BIT;
    spi_init_struct.clock_polarity = SPI_CLOCK_POLARITY_LOW;
    spi_init_struct.clock_phase = SPI_CLOCK_PHASE_1EDGE;
    spi_init_struct.cs_mode_selection = SPI_CS_SOFTWARE_MODE;

    spi_init(SPI1, &spi_init_struct);
    spi_enable(SPI1, TRUE);
}

uint8_t spi_transfer_byte(uint8_t data)
{
    // Wait until transmit buffer is empty
    while(spi_i2s_flag_get(SPI1, SPI_I2S_TDBE_FLAG) == RESET);
    spi_i2s_data_transmit(SPI1, data);

    // Wait until receive buffer is not empty
    while(spi_i2s_flag_get(SPI1, SPI_I2S_RDBF_FLAG) == RESET);
    return spi_i2s_data_receive(SPI1);
}
```

### USART Configuration and Communication

Initialize USART for serial communication

```c
#include "at32f403a_407_usart.h"

void usart_init_config(void)
{
    gpio_init_type gpio_init_struct;

    // Enable clocks
    crm_periph_clock_enable(CRM_USART1_PERIPH_CLOCK, TRUE);
    crm_periph_clock_enable(CRM_GPIOA_PERIPH_CLOCK, TRUE);

    // Configure GPIO (PA9=TX, PA10=RX)
    gpio_default_para_init(&gpio_init_struct);
    gpio_init_struct.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
    gpio_init_struct.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
    gpio_init_struct.gpio_mode = GPIO_MODE_MUX;
    gpio_init_struct.gpio_pins = GPIO_PINS_9;
    gpio_init_struct.gpio_pull = GPIO_PULL_NONE;
    gpio_init(GPIOA, &gpio_init_struct);

    gpio_init_struct.gpio_pins = GPIO_PINS_10;
    gpio_init(GPIOA, &gpio_init_struct);

    // USART configuration
    usart_init(USART1, 115200, USART_DATA_8BITS, USART_STOP_1_BIT);
    usart_transmitter_enable(USART1, TRUE);
    usart_receiver_enable(USART1, TRUE);
    usart_enable(USART1, TRUE);
}

void usart_send_byte(uint8_t data)
{
    while(usart_flag_get(USART1, USART_TDBE_FLAG) == RESET);
    usart_data_transmit(USART1, data);
}

uint8_t usart_receive_byte(void)
{
    while(usart_flag_get(USART1, USART_RDBF_FLAG) == RESET);
    return usart_data_receive(USART1);
}

void usart_send_string(char *str)
{
    while(*str)
    {
        usart_send_byte(*str++);
    }
}
```

### Timer PWM Generation

Configure timer for PWM output

```c
#include "at32f403a_407_tmr.h"

void tmr_pwm_init(void)
{
    tmr_output_config_type tmr_output_struct;
    gpio_init_type gpio_init_struct;

    // Enable clocks
    crm_periph_clock_enable(CRM_TMR2_PERIPH_CLOCK, TRUE);
    crm_periph_clock_enable(CRM_GPIOA_PERIPH_CLOCK, TRUE);

    // Configure GPIO (PA0=TMR2_CH1)
    gpio_default_para_init(&gpio_init_struct);
    gpio_init_struct.gpio_pins = GPIO_PINS_0;
    gpio_init_struct.gpio_mode = GPIO_MODE_MUX;
    gpio_init_struct.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
    gpio_init_struct.gpio_pull = GPIO_PULL_NONE;
    gpio_init_struct.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
    gpio_init(GPIOA, &gpio_init_struct);

    // Timer base configuration (1 kHz PWM)
    tmr_base_init(TMR2, 999, 119);  // Period=1000, Prescaler=120
    tmr_cnt_dir_set(TMR2, TMR_COUNT_UP);

    // PWM mode configuration
    tmr_output_default_para_init(&tmr_output_struct);
    tmr_output_struct.oc_mode = TMR_OUTPUT_CONTROL_PWM_MODE_A;
    tmr_output_struct.oc_output_state = TRUE;
    tmr_output_struct.oc_polarity = TMR_OUTPUT_ACTIVE_HIGH;
    tmr_output_struct.oc_idle_state = FALSE;
    tmr_output_channel_config(TMR2, TMR_SELECT_CHANNEL_1, &tmr_output_struct);

    // Set duty cycle (50%)
    tmr_channel_value_set(TMR2, TMR_SELECT_CHANNEL_1, 500);

    // Enable timer
    tmr_output_channel_buffer_enable(TMR2, TMR_SELECT_CHANNEL_1, TRUE);
    tmr_counter_enable(TMR2, TRUE);
}

void tmr_set_duty_cycle(uint16_t duty)
{
    tmr_channel_value_set(TMR2, TMR_SELECT_CHANNEL_1, duty);
}
```

### DMA Memory to Peripheral Transfer

Configure DMA for memory to peripheral transfer

```c
#include "at32f403a_407_dma.h"

void dma_config_mem_to_periph(uint32_t *src_buffer, uint32_t periph_addr, uint32_t length)
{
    dma_init_type dma_init_struct;

    // Enable DMA clock
    crm_periph_clock_enable(CRM_DMA1_PERIPH_CLOCK, TRUE);

    // Reset DMA channel
    dma_reset(DMA1_CHANNEL1);

    // Configure DMA
    dma_default_para_init(&dma_init_struct);
    dma_init_struct.buffer_size = length;
    dma_init_struct.direction = DMA_DIR_MEMORY_TO_PERIPHERAL;
    dma_init_struct.memory_base_addr = (uint32_t)src_buffer;
    dma_init_struct.memory_data_width = DMA_MEMORY_DATA_WIDTH_WORD;
    dma_init_struct.memory_inc_enable = TRUE;
    dma_init_struct.peripheral_base_addr = periph_addr;
    dma_init_struct.peripheral_data_width = DMA_PERIPHERAL_DATA_WIDTH_WORD;
    dma_init_struct.peripheral_inc_enable = FALSE;
    dma_init_struct.priority = DMA_PRIORITY_MEDIUM;
    dma_init_struct.loop_mode_enable = FALSE;

    dma_init(DMA1_CHANNEL1, &dma_init_struct);

    // Enable DMA channel
    dma_channel_enable(DMA1_CHANNEL1, TRUE);
}
```

### GPIO Configuration

Configure GPIO pins for various modes

```c
#include "at32f403a_407_gpio.h"
#include "at32f403a_407_crm.h"

void gpio_output_init(void)
{
    gpio_init_type gpio_init_struct;

    // Enable GPIO clock
    crm_periph_clock_enable(CRM_GPIOC_PERIPH_CLOCK, TRUE);

    // Configure PC13 as output (LED pin)
    gpio_default_para_init(&gpio_init_struct);
    gpio_init_struct.gpio_pins = GPIO_PINS_13;
    gpio_init_struct.gpio_mode = GPIO_MODE_OUTPUT;
    gpio_init_struct.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
    gpio_init_struct.gpio_pull = GPIO_PULL_NONE;
    gpio_init_struct.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
    gpio_init(GPIOC, &gpio_init_struct);
}

void gpio_input_init(void)
{
    gpio_init_type gpio_init_struct;

    // Enable GPIO clock
    crm_periph_clock_enable(CRM_GPIOA_PERIPH_CLOCK, TRUE);

    // Configure PA0 as input with pull-down (button pin)
    gpio_default_para_init(&gpio_init_struct);
    gpio_init_struct.gpio_pins = GPIO_PINS_0;
    gpio_init_struct.gpio_mode = GPIO_MODE_INPUT;
    gpio_init_struct.gpio_pull = GPIO_PULL_DOWN;
    gpio_init(GPIOA, &gpio_init_struct);
}

void gpio_toggle_led(void)
{
    gpio_bits_write(GPIOC, GPIO_PINS_13,
                   !gpio_output_data_bit_read(GPIOC, GPIO_PINS_13));
}

uint8_t gpio_read_button(void)
{
    return gpio_input_data_bit_read(GPIOA, GPIO_PINS_0);
}
```

### External Interrupt Configuration

Configure external interrupt on GPIO pin

```c
#include "at32f403a_407_exint.h"

void exint_config(void)
{
    exint_init_type exint_init_struct;
    gpio_init_type gpio_init_struct;

    // Enable clocks
    crm_periph_clock_enable(CRM_GPIOA_PERIPH_CLOCK, TRUE);
    crm_periph_clock_enable(CRM_IOMUX_PERIPH_CLOCK, TRUE);

    // Configure PA0 as input
    gpio_default_para_init(&gpio_init_struct);
    gpio_init_struct.gpio_pins = GPIO_PINS_0;
    gpio_init_struct.gpio_mode = GPIO_MODE_INPUT;
    gpio_init_struct.gpio_pull = GPIO_PULL_DOWN;
    gpio_init(GPIOA, &gpio_init_struct);

    // Connect EXINT line to GPIO pin
    gpio_exint_line_config(GPIO_PORT_SOURCE_GPIOA, GPIO_PINS_SOURCE0);

    // Configure EXINT
    exint_default_para_init(&exint_init_struct);
    exint_init_struct.line_enable = TRUE;
    exint_init_struct.line_mode = EXINT_LINE_INTERRUPUT;
    exint_init_struct.line_select = EXINT_LINE_0;
    exint_init_struct.line_polarity = EXINT_TRIGGER_RISING_EDGE;
    exint_init(&exint_init_struct);

    // Enable NVIC
    nvic_irq_enable(EXINT0_IRQn, 0, 0);
}

void EXINT0_IRQHandler(void)
{
    if(exint_flag_get(EXINT_LINE_0) != RESET)
    {
        // Handle interrupt
        handle_button_press();

        // Clear flag
        exint_flag_clear(EXINT_LINE_0);
    }
}
```

### RTC Configuration

Initialize Real-Time Clock

```c
#include "at32f403a_407_rtc.h"
#include "at32f403a_407_pwc.h"
#include "at32f403a_407_bpr.h"

void rtc_config(void)
{
    // Enable PWC and BPR clocks
    crm_periph_clock_enable(CRM_PWC_PERIPH_CLOCK, TRUE);
    crm_periph_clock_enable(CRM_BPR_PERIPH_CLOCK, TRUE);

    // Enable access to backup domain
    pwc_battery_powered_domain_access(TRUE);

    // Reset backup domain
    crm_battery_powered_domain_reset(TRUE);
    crm_battery_powered_domain_reset(FALSE);

    // Enable LEXT (32.768 kHz external crystal)
    crm_clock_source_enable(CRM_CLOCK_SOURCE_LEXT, TRUE);
    while(crm_flag_get(CRM_LEXT_STABLE_FLAG) == RESET);

    // Select LEXT as RTC clock source
    crm_rtc_clock_select(CRM_RTC_CLOCK_LEXT);
    crm_rtc_clock_enable(TRUE);

    // Wait for RTC registers synchronization
    rtc_wait_for_synchro();

    // Wait for RTC register access
    rtc_wait_config_finish();

    // Set RTC divider (32768 - 1)
    rtc_divider_set(32767);

    // Wait for configuration to finish
    rtc_wait_config_finish();
}

void rtc_set_time(uint32_t timestamp)
{
    rtc_wait_config_finish();
    rtc_counter_set(timestamp);
    rtc_wait_config_finish();
}

uint32_t rtc_get_time(void)
{
    return rtc_counter_get();
}
```

### Watchdog Timer Configuration

Configure independent watchdog timer

```c
#include "at32f403a_407_wdt.h"

void wdt_init(uint16_t timeout_ms)
{
    // Enable write access to WDT registers
    wdt_enable();
    wdt_register_write_enable(TRUE);

    // Configure divider and reload value
    // LICK = 40 kHz, timeout = (4 * 2^div * reload) / 40000
    wdt_divider_set(WDT_CLK_DIV_32);  // 32 divider
    wdt_reload_value_set((timeout_ms * 40) / 128);  // Calculate reload value

    // Reload counter
    wdt_counter_reload();

    // Disable write access
    wdt_register_write_enable(FALSE);
}

void wdt_feed(void)
{
    wdt_counter_reload();
}
```

### Power Management - Sleep Mode

Enter sleep mode with wake-up configuration

```c
#include "at32f403a_407_pwc.h"

void enter_sleep_mode(void)
{
    // Configure wake-up sources (e.g., EXINT, RTC)
    // ... (configure interrupts as needed)

    // Enter sleep mode using WFI instruction
    pwc_sleep_mode_enter(PWC_SLEEP_ENTER_WFI);

    // CPU wakes up here when interrupt occurs
}

void enter_deepsleep_mode(void)
{
    // Save power by disabling unnecessary peripherals
    // ... (disable unused clocks)

    // Configure voltage regulator
    pwc_voltage_regulate_set(PWC_REGULATOR_LOW_POWER);

    // Enter deepsleep mode
    pwc_deep_sleep_mode_enter(PWC_DEEP_SLEEP_ENTER_WFI);

    // CPU wakes up here and restores clocks
}
```

### USB Device Configuration

Initialize USB device peripheral

```c
#include "at32f403a_407_usb.h"

void usb_device_init(void)
{
    // Enable USB clock
    crm_periph_clock_enable(CRM_USB_PERIPH_CLOCK, TRUE);
    crm_usb_clock_div_set(CRM_USB_DIV_2_5);  // 120MHz / 2.5 = 48MHz

    // Enable USB interrupts
    nvic_irq_enable(OTGFS1_IRQn, 0, 0);

    // Initialize USB peripheral
    usb_global_init();

    // Configure device mode
    usb_device_init();
}
```

## Integration and Usage Summary

This comprehensive MCU documentation repository enables developers to successfully deploy AT32F403A/407 microcontrollers in production systems through multiple integrated resources: (1) 26 detailed peripheral documentation files covering all major subsystems with complete API references, code examples, and best practices, (2) complete firmware library v2.2.1 with 26 peripheral driver headers and 25 implementation files providing production-ready driver code, (3) CMSIS ARM Cortex-M4 core support for standard embedded development workflows, (4) intelligent taxonomy system with 5 YAML files enabling Context7 semantic search for natural language queries, and (5) comprehensive technical content totaling over 25,000 lines of documentation. Primary use cases include firmware development with documented API references, peripheral initialization using provided code examples, driver integration leveraging the firmware library, Context7 AI integration for intelligent MCU queries, and hardware debugging with detailed peripheral behavior documentation.

Integration patterns follow a multi-layered approach: developers start by exploring the peripheral documentation files in the docs/ folder to understand initialization sequences and API usage patterns, then leverage the firmware library drivers (at32f403a_407_*.h/c files) for production-grade peripheral implementations, and finally use the taxonomy system for semantic search of specific functionality. The repository provides detailed peripheral guides for critical subsystems including CAN (Controller Area Network with dual controllers, 14 filters, and 1 Mbps support), Flash (dual-bank architecture with SPIM external flash and security library protection), ADC (3x 12-bit ADCs with DMA support and 2 MSPS sampling), USART (5 controllers with DMA, LIN, IrDA, and SmartCard support), TMR (10 timers with advanced PWM, encoder, and input capture), I2C (2 controllers with 400 kHz Fast Mode and SMBus support), SPI (4 controllers up to 60 Mbps), USB (USB 2.0 Full Speed device/host/OTG), DMA (12 channels with flexible request routing), and GPIO (up to 144 I/O pins with alternate function mapping). Context7 users benefit from YAML-structured metadata enabling intelligent queries like "show me SPI DMA initialization code" or "how to configure CAN filters" with direct navigation to relevant documentation and code examples. For device errata and silicon limitations, developers should download the official ES0002 errata sheet from Artery Technology's website, which documents 41 known issues with detailed workarounds for critical areas affecting Flash operations, CAN communication, and power management functionality.