#include "stm32g474xx.h"

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Enumerations
enum	PHAL_USART_Idx_t { USART1_IDX = 0 , USART2_IDX = 1 , USART3_IDX = 2 , NUM_USART }

Functions
bool	PHAL_USART_init (PHAL_USART_Idx_t periph_idx, uint32_t baud_rate, const uint32_t clock_rate)
	Initialize a USART peripheral for DMA-driven communication.

bool	PHAL_USART_tx (PHAL_USART_Idx_t periph_idx, uint8_t *data, uint16_t len)
	Start a transmission using DMA.

void	PHAL_USART_rx (PHAL_USART_Idx_t periph_idx, uint8_t *data, uint16_t len, bool cont)
	Start a reception using DMA of a specific length.

bool	PHAL_USART_txBusy (PHAL_USART_Idx_t periph_idx)
	Returns whether the USART peripheral is currently transmitting data.

uint16_t	PHAL_USART_rxCount (PHAL_USART_Idx_t periph_idx)
	Number of bytes received in the last completed frame.

bool	PHAL_USART_txBlocking (PHAL_USART_Idx_t periph_idx, uint8_t *data, uint16_t len)
	Transmit data, blocking until the transfer completes.

void	PHAL_USART_rxBlocking (PHAL_USART_Idx_t periph_idx, uint8_t *data, uint16_t len)
	Receive data, blocking until a one-shot reception completes.

void	PHAL_USART_rxCallback (PHAL_USART_Idx_t periph_idx, uint16_t len)
	Weak callback invoked when a full RX frame is received. Override in application code. Runs in ISR context, so keep it light.

Enumeration Type Documentation

◆ PHAL_USART_Idx_t

enum PHAL_USART_Idx_t

Enumerator
USART1_IDX
USART2_IDX
USART3_IDX
NUM_USART

Function Documentation

◆ PHAL_USART_init()

bool PHAL_USART_init	(	PHAL_USART_Idx_t	periph_idx,
		uint32_t	baud_rate,
		const uint32_t	clock_rate )

Initialize a USART peripheral for DMA-driven communication.

Enables the peripheral clock and applies a fixed frame format:

8 data bits, no parity, 1 stop bit (8N1)
16x oversampling
no hardware flow control Derives the baud-rate divisor from clock_rate, enables the IDLE-line interrupt (RX frame completion) and the TX DMA transfer-complete interrupt, then initializes the TX and RX DMA channels.

Call once per USART before any tx/rx. The USART GPIO pins must already be configured by the caller.

Parameters

periph_idx	Which USART peripheral to initialize
baud_rate	Desired baud rate
clock_rate	Frequency (Hz) of the bus clock feeding this USART (APBx)

Returns: true on success, false if DMA init failed

Parameters

periph_idx	Which USART peripheral to initialize
baud_rate	Desired baud rate
clock_rate	Frequency (Hz) of the bus clock feeding this USART (APB1/APB2)

Returns: true on success, false if DMA init failed

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◆ PHAL_USART_rx()

void PHAL_USART_rx	(	PHAL_USART_Idx_t	periph_idx,
		uint8_t *	data,
		uint16_t	len,
		bool	cont )

Start a reception using DMA of a specific length.

Parameters

periph_idx	Which USART peripheral to receive on
data	The address to put the received data
len	Maximum number of bytes (the buffer size). A frame shorter than this still completes on the IDLE line; the actual count is reported to PHAL_USART_rxCallback. uint16_t because that is the DMA's transfer counter width.
cont	Enable continuous RX using the IDLE-line interrupt. When set, call this function once and the HAL keeps receiving frames of the same maximum length, invoking PHAL_USART_rxCallback after each.

Start a reception using DMA of a specific length.

Parameters

periph_idx	Which USART peripheral to receive on
data	Buffer to receive into
len	Maximum number of bytes to receive (buffer size)
cont	Enable continuous RX. When set, call this once and the HAL keeps receiving frames of the same maximum length, invoking PHAL_USART_rxCallback after each.

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◆ PHAL_USART_rxBlocking()

void PHAL_USART_rxBlocking	(	PHAL_USART_Idx_t	periph_idx,
		uint8_t *	data,
		uint16_t	len )

Receive data, blocking until a one-shot reception completes.

Starts a one-shot DMA reception (see PHAL_USART_rx) and busy-waits until the IDLE-line ISR signals the frame is complete. Call PHAL_USART_rxCount() afterwards for the byte count. Do not call from an ISR.

Parameters

periph_idx	Which USART peripheral to receive on
data	Buffer to receive into
len	Maximum number of bytes to receive
periph_idx	Which USART peripheral to receive on
data	Buffer to receive into
len	Number of bytes to receive

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◆ PHAL_USART_rxCallback()

void PHAL_USART_rxCallback	(	PHAL_USART_Idx_t	periph_idx,
		uint16_t	len )

extern

Weak callback invoked when a full RX frame is received. Override in application code. Runs in ISR context, so keep it light.

Parameters

periph_idx	Which USART peripheral received the frame
len	Number of bytes in this frame. Bytes past this offset in the buffer are stale and must not be decoded.

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◆ PHAL_USART_rxCount()

uint16_t PHAL_USART_rxCount ( PHAL_USART_Idx_t periph_idx )

Number of bytes received in the last completed frame.

The IDLE line ends a frame whenever the sender stops, which may be short of the length passed to PHAL_USART_rx. Anything past this count in the buffer is leftover from an earlier frame.

Parameters

periph_idx Which USART peripheral to query

Returns: byte count, valid once PHAL_USART_rxCallback has fired (or PHAL_USART_rxBlocking has returned)

Parameters

periph_idx Which USART peripheral to query

Returns: byte count, valid once PHAL_USART_rxCallback has fired

◆ PHAL_USART_tx()

bool PHAL_USART_tx	(	PHAL_USART_Idx_t	periph_idx,
		uint8_t *	data,
		uint16_t	len )

Start a transmission using DMA.

Fails rather than truncating a transfer already in flight - poll PHAL_USART_txBusy() (or use PHAL_USART_txBlocking) before calling again.

Parameters

periph_idx	Which USART peripheral to transmit on
data	The address of the data to send
len	Number of bytes.

Returns: true if every DMA reconfiguration step succeeded, false if a transmission is already in flight or a step failed

Start a transmission using DMA.

Parameters

periph_idx	Which USART peripheral to transmit on
data	Buffer to send
len	Number of bytes to send

Returns: true if every DMA reconfiguration step succeeded, false if a transmission is already in flight or a step failed

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◆ PHAL_USART_txBlocking()

bool PHAL_USART_txBlocking	(	PHAL_USART_Idx_t	periph_idx,
		uint8_t *	data,
		uint16_t	len )

Transmit data, blocking until the transfer completes.

Starts a DMA transmission (see PHAL_USART_tx) and busy-waits until the USART reports the frame fully shifted out. Do not call from an ISR.

Parameters

periph_idx	Which USART peripheral to transmit on
data	Buffer to send
len	Number of bytes to send

Returns: true if the transfer completed, false if it failed to start

Parameters

periph_idx	Which USART peripheral to transmit on
data	Buffer to send
len	Number of bytes to send

Returns: true if the transfer completed, false if it failed to start

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◆ PHAL_USART_txBusy()

bool PHAL_USART_txBusy ( PHAL_USART_Idx_t periph_idx )

Returns whether the USART peripheral is currently transmitting data.

Tracks the USART's own transmission-complete flag, so it stays true until the last bit has left the wire - not merely until the DMA has finished writing to the data register.

Parameters

periph_idx Which USART peripheral to check

Returns: true if the peripheral is currently sending a message, false otherwise

Returns whether the USART peripheral is currently transmitting data.

Parameters

periph_idx Which USART peripheral to check

Returns: true if a transmission is in flight, false otherwise

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Enumerations

Functions

Enumeration Type Documentation

◆ PHAL_USART_Idx_t

Function Documentation

◆ PHAL_USART_init()

◆ PHAL_USART_rx()

◆ PHAL_USART_rxBlocking()

◆ PHAL_USART_rxCallback()

◆ PHAL_USART_rxCount()

◆ PHAL_USART_tx()

◆ PHAL_USART_txBlocking()

◆ PHAL_USART_txBusy()