UART

group UART Driver

Generic UART driver implementation for Chimera-SDK.

UART Parity Modes

Defines available parity options for UART.

UART_PARITY_NONE: No parity.

UART_PARITY_EVEN: Even parity.

UART_PARITY_ODD: Odd parity.

Default UART Configurations

Defines default UART settings, which can be overridden at compile-time.

UART_DEFAULT_BAUD_RATE: Default baud rate (bps).

UART_DEFAULT_DATA_BITS: Default number of data bits.

UART_DEFAULT_PARITY: Default parity mode.

UART_DEFAULT_STOP_BITS: Default number of stop bits.

UART_CLK_FREQ_HZ: Default clock frequency in Hz.

UART_BASE_ADDR: Default base address for UART.

Functions

void _uart_init(void): Initializes the UART interface. This function sets up the UART hardware with the specified configuration.

void _uart_deinit(void): De-initializes the UART interface. This function releases any resources held by the UART driver.

int uart_putc(char c, FILE *file)

Puts a character to the UART.

Parameters:

c – Character to send.
file – Pointer to the FILE structure (unused).

Returns:

The character written as an unsigned char cast to an int or EOF on error.

Variables

const uart_config_t default_uart_cfg

Default UART configuration settings.

This global configuration structure defines default parameters for UART communication, which can be overridden by the user.

Default Configuration:

uart_config_t default_cfg = {
    .baud_rate   = UART_DEFAULT_BAUD_RATE,
    .clk_freq_hz = UART_CLK_FREQ_HZ,
    .data_bits   = UART_DEFAULT_DATA_BITS,
    .parity      = UART_DEFAULT_PARITY,
    .stop_bits   = UART_DEFAULT_STOP_BITS
};

const chi_interface_api_t default_uart_api

UART HAL API structure.

This structure defines function pointers for UART operations, allowing for modular driver implementations.

chi_interface_api_t uart_api = {
    .open  = uart_open,
    .close = uart_close,
    .read  = uart_read,
    .write = uart_write,
    .flush = uart_flush
};

chi_interface_t default_uart_inst

struct uart_config_t

#include <uart.h>

UART configuration structure.

This structure holds the configuration settings for UART initialization.

Public Members

uint32_t baud_rate: Baud rate in bits per second.

uint32_t clk_freq_hz: Clock frequency in Hz.

uint8_t data_bits: Number of data bits (typically 8).

uint8_t parity: Parity setting (None, Even, Odd).

uint8_t stop_bits: Number of stop bits (1 or 2).

APB UART Driver

The APB UART driver implementation for Chimera-SDK. This driver provides initialization, read, and write functions for an APB-based UART peripheral.

group UART APB Driver

APB UART driver implementation for Chimera-SDK.

APB UART register definitions for Chimera-SDK.

This file provides the implementation of UART initialization, read, and write functions for an APB-based UART peripheral. It includes blocking read and write operations along with basic configuration.

This file defines register offsets and fields for an APB-based UART peripheral. It is used in conjunction with the UART driver to configure and interact with the hardware.

UART Register Offsets

Defines the register offsets for the APB UART peripheral.

UART_RBR_REG_OFFSET: Receiver Buffer Register (RBR) Offset.

UART_THR_REG_OFFSET: Transmitter Holding Register (THR) Offset.

UART_INTR_ENABLE_REG_OFFSET: Interrupt Enable Register (IER) Offset.

UART_INTR_IDENT_REG_OFFSET: Interrupt Identification Register (IIR) Offset.

UART_FIFO_CONTROL_REG_OFFSET: FIFO Control Register (FCR) Offset.

UART_LINE_CONTROL_REG_OFFSET: Line Control Register (LCR) Offset.

UART_MODEM_CONTROL_REG_OFFSET: Modem Control Register (MCR) Offset.

UART_LINE_STATUS_REG_OFFSET: Line Status Register (LSR) Offset.

UART_MODEM_STATUS_REG_OFFSET: Modem Status Register (MSR) Offset.

UART_DLAB_LSB_REG_OFFSET: Divisor Latch LSB Register (DLAB_LSB) Offset.

UART_DLAB_MSB_REG_OFFSET: Divisor Latch MSB Register (DLAB_MSB) Offset.

UART Line Status Register (LSR) Bit Definitions

Defines the bit positions for the Line Status Register (LSR).

UART_LINE_STATUS_DATA_READY_BIT: Data Ready (DR) bit. Set when data is available in RBR.

UART_LINE_STATUS_THR_EMPTY_BIT: Transmitter Holding Register (THR) empty bit.

UART_LINE_STATUS_TMIT_EMPTY_BIT: Transmitter empty bit. Set when both THR and shift register are empty.

Functions

static inline int rx_ready(uint32_t base)

Checks if data is available to read from the UART receiver.

Parameters:: base – Base address of the UART peripheral.
Returns:: 1 if data is ready, 0 otherwise.

static inline int tx_ready(uint32_t base)

Checks if the transmitter is ready to accept new data.

Parameters:: base – Base address of the UART peripheral.
Returns:: 1 if the transmitter is ready, 0 otherwise.

static inline int tx_empty(uint32_t base)

Checks if the transmitter is completely empty.

Parameters:: base – Base address of the UART peripheral.
Returns:: 1 if the transmitter is empty, 0 otherwise.

int uart_apb_flush(const chi_interface_t *iface)

Flushes the UART transmitter, ensuring all data is sent.

Parameters:: iface – UART interface instance.
Returns:: 0 on success, -1 on failure.

int uart_apb_open(const chi_interface_t *iface)

Opens and initializes the UART interface.

Parameters:: iface – UART interface instance.
Returns:: 0 on success, -1 on failure.

int uart_apb_close(const chi_interface_t *iface)

Closes the UART interface.

Parameters:: iface – UART interface instance.
Returns:: 0 on success, -1 on failure.

ssize_t uart_apb_read(const chi_interface_t *iface, void *buffer, uint32_t size, chi_interface_callback_t cb)

Reads data from the UART receiver (blocking mode).

Parameters:

iface – UART interface instance.
buffer – Buffer to store received data.
size – Number of bytes to read.
cb – Optional callback function (set to NULL if not needed).

Returns:

Number of bytes read on success, -1 on failure.

ssize_t uart_apb_write(const chi_interface_t *iface, const void *buffer, uint32_t size, chi_interface_callback_t cb)

Writes data to the UART transmitter (blocking mode).

Parameters:

iface – UART interface instance.
buffer – Data to send.
size – Number of bytes to write.
cb – Optional callback function (set to NULL if not needed).

Returns:

Number of bytes written on success, -1 on failure.