Receiver Transmitter (USART)
The Universal Synchronous Asynchronous Receiver Transceiver (USART) provides one full duplex universal synchronous asynchronous serial link. Data frame format is widely programmable (data length, parity, number of stop bits) to support a maximum of standards. The receiver implements parity error, framing error and overrun error detection. The receiver time-out enables handling variable-length frames and the transmitter timeguard facilitates communications with slow remote devices. Multidrop communications are also supported through address bit handling in reception and transmission. The driver supports the following modes: RS232, RS485, SPI, IrDA, ISO7816, MODEM, Hardware handshaking and LIN.
Macros | |
#define | HIGH_FRQ_SAMPLE_DIV 16 |
#define | ISO7816_T_0 0 |
#define | ISO7816_T_1 1 |
#define | LOW_FRQ_SAMPLE_DIV 8 |
#define | MAX_CD_VALUE US_BRGR_CD_Msk |
#define | MAX_TRAN_GUARD_TIME US_TTGR_TG_Msk |
#define | MIN_CD_VALUE 0x01 |
#define | MIN_CD_VALUE_SPI 0x04 |
#define | US_WPMR_WPKEY_PASSWD US_WPMR_WPKEY(0x555341U) |
#define | USART_PARITY_ERROR 5 |
Functions | |
void | usart_disable_interrupt (Usart *p_usart, uint32_t ul_sources) |
Disable USART interrupts. More... | |
void | usart_disable_rx (Usart *p_usart) |
Disable USART receiver. More... | |
void | usart_disable_tx (Usart *p_usart) |
Disable USART transmitter. More... | |
void | usart_disable_writeprotect (Usart *p_usart) |
Disable write protect of USART registers. More... | |
void | usart_drive_RTS_pin_high (Usart *p_usart) |
Drive the pin RTS to 1. More... | |
void | usart_drive_RTS_pin_low (Usart *p_usart) |
Drive the pin RTS to 0. More... | |
void | usart_enable_interrupt (Usart *p_usart, uint32_t ul_sources) |
Enable USART interrupts. More... | |
void | usart_enable_rx (Usart *p_usart) |
Enable USART receiver. More... | |
void | usart_enable_tx (Usart *p_usart) |
Enable USART transmitter. More... | |
void | usart_enable_writeprotect (Usart *p_usart) |
Enable write protect of USART registers. More... | |
uint32_t | usart_get_interrupt_mask (Usart *p_usart) |
Read USART interrupt mask. More... | |
uint32_t | usart_get_status (Usart *p_usart) |
Get current status. More... | |
uint32_t | usart_get_writeprotect_status (Usart *p_usart) |
Get write protect status. More... | |
uint32_t | usart_getchar (Usart *p_usart, uint32_t *c) |
Read from USART Receive Holding Register. More... | |
uint32_t | usart_init_hw_handshaking (Usart *p_usart, const sam_usart_opt_t *p_usart_opt, uint32_t ul_mck) |
Configure USART to work in hardware handshaking mode. More... | |
uint32_t | usart_init_rs232 (Usart *p_usart, const sam_usart_opt_t *p_usart_opt, uint32_t ul_mck) |
Configure USART to work in RS232 mode. More... | |
uint32_t | usart_init_rs485 (Usart *p_usart, const sam_usart_opt_t *p_usart_opt, uint32_t ul_mck) |
Configure USART to work in RS485 mode. More... | |
uint32_t | usart_init_spi_master (Usart *p_usart, const usart_spi_opt_t *p_usart_opt, uint32_t ul_mck) |
Configure USART to work in SPI mode and act as a master. More... | |
uint32_t | usart_init_spi_slave (Usart *p_usart, const usart_spi_opt_t *p_usart_opt) |
Configure USART to work in SPI mode and act as a slave. More... | |
uint32_t | usart_init_sync_master (Usart *p_usart, const sam_usart_opt_t *p_usart_opt, uint32_t ul_mck) |
Configure USART to work in SYNC mode and act as a master. More... | |
uint32_t | usart_init_sync_slave (Usart *p_usart, const sam_usart_opt_t *p_usart_opt) |
Configure USART to work in SYNC mode and act as a slave. More... | |
uint32_t | usart_is_rx_ready (Usart *p_usart) |
Check if the received data are ready. More... | |
uint32_t | usart_is_tx_empty (Usart *p_usart) |
Check if Transmit Holding Register is empty. More... | |
uint32_t | usart_is_tx_ready (Usart *p_usart) |
Check if Transmit is Ready. More... | |
uint32_t | usart_putchar (Usart *p_usart, uint32_t c) |
Write to USART Transmit Holding Register. More... | |
uint32_t | usart_read (Usart *p_usart, uint32_t *c) |
Read from USART Receive Holding Register. More... | |
void | usart_reset (Usart *p_usart) |
Reset the USART and disable TX and RX. More... | |
void | usart_reset_rx (Usart *p_usart) |
Immediately stop and disable USART receiver. More... | |
void | usart_reset_status (Usart *p_usart) |
Reset status bits (PARE, OVER, MANERR, UNRE and PXBRK in US_CSR). More... | |
void | usart_reset_tx (Usart *p_usart) |
Immediately stop and disable USART transmitter. More... | |
void | usart_restart_rx_timeout (Usart *p_usart) |
Restart the receive timeout. More... | |
uint32_t | usart_send_address (Usart *p_usart, uint32_t ul_addr) |
In Multidrop mode only, the next character written to the US_THR is sent with the address bit set. More... | |
uint32_t | usart_set_async_baudrate (Usart *p_usart, uint32_t baudrate, uint32_t ul_mck) |
Calculate a clock divider(CD) and a fractional part (FP) for the USART asynchronous modes to generate a baudrate as close as possible to the baudrate set point. More... | |
void | usart_set_rx_timeout (Usart *p_usart, uint32_t timeout) |
Configure the receive timeout register. More... | |
static uint32_t | usart_set_spi_master_baudrate (Usart *p_usart, uint32_t baudrate, uint32_t ul_mck) |
Calculate a clock divider (CD) for the USART SPI master mode to generate a baud rate as close as possible to the baud rate set point. More... | |
static void | usart_set_spi_slave_baudrate (Usart *p_usart) |
Select the SCK pin as the source of baudrate for the USART SPI slave mode. More... | |
static uint32_t | usart_set_sync_master_baudrate (Usart *p_usart, uint32_t baudrate, uint32_t ul_mck) |
Calculate a clock divider for the USART synchronous master modes to generate a baudrate as close as possible to the baudrate set point. More... | |
static void | usart_set_sync_slave_baudrate (Usart *p_usart) |
Select the SCK pin as the source of baud rate for the USART synchronous slave modes. More... | |
void | usart_set_tx_timeguard (Usart *p_usart, uint32_t timeguard) |
Configure the transmit timeguard register. More... | |
void | usart_spi_force_chip_select (Usart *p_usart) |
Drive the slave select line NSS (RTS pin) to 0 in SPI master mode. More... | |
void | usart_spi_release_chip_select (Usart *p_usart) |
Drive the slave select line NSS (RTS pin) to 1 in SPI master mode. More... | |
void | usart_start_rx_timeout (Usart *p_usart) |
Start waiting for a character before clocking the timeout count. More... | |
void | usart_start_tx_break (Usart *p_usart) |
Start transmission of a break. More... | |
void | usart_stop_tx_break (Usart *p_usart) |
Stop transmission of a break. More... | |
uint32_t | usart_write (Usart *p_usart, uint32_t c) |
Write to USART Transmit Holding Register. More... | |
void | usart_write_line (Usart *p_usart, const char *string) |
Write one-line string through USART. More... | |
#define HIGH_FRQ_SAMPLE_DIV 16 |
Referenced by usart_set_async_baudrate().
#define ISO7816_T_0 0 |
#define ISO7816_T_1 1 |
#define LOW_FRQ_SAMPLE_DIV 8 |
Referenced by usart_set_async_baudrate().
#define MAX_CD_VALUE US_BRGR_CD_Msk |
Referenced by usart_set_async_baudrate(), usart_set_spi_master_baudrate(), and usart_set_sync_master_baudrate().
#define MAX_TRAN_GUARD_TIME US_TTGR_TG_Msk |
#define MIN_CD_VALUE 0x01 |
#define MIN_CD_VALUE_SPI 0x04 |
#define US_WPMR_WPKEY_PASSWD US_WPMR_WPKEY(0x555341U) |
Referenced by usart_disable_writeprotect(), and usart_enable_writeprotect().
#define USART_PARITY_ERROR 5 |
void usart_disable_interrupt | ( | Usart * | p_usart, |
uint32_t | ul_sources | ||
) |
Disable USART interrupts.
p_usart | Pointer to a USART peripheral. |
ul_sources | Interrupt sources bit map. |
Referenced by configure_usart(), and USART0_Handler().
void usart_disable_rx | ( | Usart * | p_usart | ) |
Disable USART receiver.
p_usart | Pointer to a USART instance. |
void usart_disable_tx | ( | Usart * | p_usart | ) |
Disable USART transmitter.
p_usart | Pointer to a USART instance. |
void usart_disable_writeprotect | ( | Usart * | p_usart | ) |
Disable write protect of USART registers.
p_usart | Pointer to a USART instance. |
References US_WPMR_WPKEY_PASSWD.
Referenced by usart_reset().
void usart_drive_RTS_pin_high | ( | Usart * | p_usart | ) |
void usart_drive_RTS_pin_low | ( | Usart * | p_usart | ) |
Drive the pin RTS to 0.
p_usart | Pointer to a USART instance. |
void usart_enable_interrupt | ( | Usart * | p_usart, |
uint32_t | ul_sources | ||
) |
Enable USART interrupts.
p_usart | Pointer to a USART peripheral. |
ul_sources | Interrupt sources bit map. |
Referenced by main(), and transmit_mode_sync().
void usart_enable_rx | ( | Usart * | p_usart | ) |
Enable USART receiver.
p_usart | Pointer to a USART instance. |
Referenced by configure_usart(), and usart_serial_init().
void usart_enable_tx | ( | Usart * | p_usart | ) |
Enable USART transmitter.
p_usart | Pointer to a USART instance. |
Referenced by configure_usart(), and usart_serial_init().
void usart_enable_writeprotect | ( | Usart * | p_usart | ) |
Enable write protect of USART registers.
p_usart | Pointer to a USART instance. |
References US_WPMR_WPKEY_PASSWD.
uint32_t usart_get_interrupt_mask | ( | Usart * | p_usart | ) |
Read USART interrupt mask.
p_usart | Pointer to a USART peripheral. |
uint32_t usart_get_status | ( | Usart * | p_usart | ) |
Get current status.
p_usart | Pointer to a USART instance. |
Referenced by USART0_Handler().
uint32_t usart_get_writeprotect_status | ( | Usart * | p_usart | ) |
Get write protect status.
p_usart | Pointer to a USART instance. |
uint32_t usart_getchar | ( | Usart * | p_usart, |
uint32_t * | c | ||
) |
Read from USART Receive Holding Register.
Before reading user should check if rx is ready.
p_usart | Pointer to a USART instance. |
c | Pointer where the one-byte received data will be stored. |
0 | Data has been received. |
1 | on failure. |
uint32_t usart_init_hw_handshaking | ( | Usart * | p_usart, |
const sam_usart_opt_t * | p_usart_opt, | ||
uint32_t | ul_mck | ||
) |
Configure USART to work in hardware handshaking mode.
p_usart | Pointer to a USART instance. |
p_usart_opt | Pointer to sam_usart_opt_t instance. |
ul_mck | USART module input clock frequency. |
0 | on success. |
1 | on failure. |
References usart_init_rs232().
uint32_t usart_init_rs232 | ( | Usart * | p_usart, |
const sam_usart_opt_t * | p_usart_opt, | ||
uint32_t | ul_mck | ||
) |
Configure USART to work in RS232 mode.
p_usart | Pointer to a USART instance. |
p_usart_opt | Pointer to sam_usart_opt_t instance. |
ul_mck | USART module input clock frequency. |
0 | on success. |
1 | on failure. |
References sam_usart_opt_t::baudrate, sam_usart_opt_t::channel_mode, sam_usart_opt_t::char_length, sam_usart_opt_t::parity_type, sam_usart_opt_t::stop_bits, usart_reset(), and usart_set_async_baudrate().
Referenced by usart_init_hw_handshaking(), usart_init_rs485(), and usart_serial_init().
uint32_t usart_init_rs485 | ( | Usart * | p_usart, |
const sam_usart_opt_t * | p_usart_opt, | ||
uint32_t | ul_mck | ||
) |
Configure USART to work in RS485 mode.
p_usart | Pointer to a USART instance. |
p_usart_opt | Pointer to sam_usart_opt_t instance. |
ul_mck | USART module input clock frequency. |
0 | on success. |
1 | on failure. |
References usart_init_rs232().
uint32_t usart_init_spi_master | ( | Usart * | p_usart, |
const usart_spi_opt_t * | p_usart_opt, | ||
uint32_t | ul_mck | ||
) |
Configure USART to work in SPI mode and act as a master.
p_usart | Pointer to a USART instance. |
p_usart_opt | Pointer to sam_usart_opt_t instance. |
ul_mck | USART module input clock frequency. |
0 | on success. |
1 | on failure. |
References usart_spi_opt_t::baudrate, usart_spi_opt_t::channel_mode, usart_spi_opt_t::char_length, usart_spi_opt_t::spi_mode, SPI_MODE_0, SPI_MODE_1, SPI_MODE_2, SPI_MODE_3, usart_reset(), and usart_set_spi_master_baudrate().
uint32_t usart_init_spi_slave | ( | Usart * | p_usart, |
const usart_spi_opt_t * | p_usart_opt | ||
) |
Configure USART to work in SPI mode and act as a slave.
p_usart | Pointer to a USART instance. |
p_usart_opt | Pointer to sam_usart_opt_t instance. |
0 | on success. |
1 | on failure. |
References usart_spi_opt_t::channel_mode, usart_spi_opt_t::char_length, usart_spi_opt_t::spi_mode, SPI_MODE_0, SPI_MODE_1, SPI_MODE_2, SPI_MODE_3, usart_reset(), and usart_set_spi_slave_baudrate().
uint32_t usart_init_sync_master | ( | Usart * | p_usart, |
const sam_usart_opt_t * | p_usart_opt, | ||
uint32_t | ul_mck | ||
) |
Configure USART to work in SYNC mode and act as a master.
p_usart | Pointer to a USART instance. |
p_usart_opt | Pointer to sam_usart_opt_t instance. |
ul_mck | USART module input clock frequency. |
0 | on success. |
1 | on failure. |
References sam_usart_opt_t::baudrate, sam_usart_opt_t::channel_mode, sam_usart_opt_t::char_length, sam_usart_opt_t::parity_type, sam_usart_opt_t::stop_bits, usart_reset(), and usart_set_sync_master_baudrate().
Referenced by configure_usart().
uint32_t usart_init_sync_slave | ( | Usart * | p_usart, |
const sam_usart_opt_t * | p_usart_opt | ||
) |
Configure USART to work in SYNC mode and act as a slave.
p_usart | Pointer to a USART instance. |
p_usart_opt | Pointer to sam_usart_opt_t instance. |
0 | on success. |
1 | on failure. |
References sam_usart_opt_t::channel_mode, sam_usart_opt_t::char_length, sam_usart_opt_t::parity_type, sam_usart_opt_t::stop_bits, usart_reset(), and usart_set_sync_slave_baudrate().
Referenced by configure_usart().
uint32_t usart_is_rx_ready | ( | Usart * | p_usart | ) |
Check if the received data are ready.
Check if Data have been received and loaded into USART_RHR.
p_usart | Pointer to a USART instance. |
1 | Some data has been received. |
0 | No data has been received. |
Referenced by usart_serial_is_rx_ready().
uint32_t usart_is_tx_empty | ( | Usart * | p_usart | ) |
Check if Transmit Holding Register is empty.
Check if the last data written in USART_THR have been loaded in TSR and the last data loaded in TSR have been transmitted.
p_usart | Pointer to a USART instance. |
1 | Transmitter is empty. |
0 | Transmitter is not empty. |
Referenced by transmit_mode_sync().
uint32_t usart_is_tx_ready | ( | Usart * | p_usart | ) |
Check if Transmit is Ready.
Check if data have been loaded in USART_THR and are waiting to be loaded into the Transmit Shift Register (TSR).
p_usart | Pointer to a USART instance. |
1 | No data is in the Transmit Holding Register. |
0 | There is data in the Transmit Holding Register. |
uint32_t usart_putchar | ( | Usart * | p_usart, |
uint32_t | c | ||
) |
Write to USART Transmit Holding Register.
p_usart | Pointer to a USART instance. |
c | Data to be sent. |
0 | on success. |
1 | on failure. |
Referenced by usart_write_line().
uint32_t usart_read | ( | Usart * | p_usart, |
uint32_t * | c | ||
) |
Read from USART Receive Holding Register.
p_usart | Pointer to a USART instance. |
c | Pointer where the one-byte received data will be stored. |
0 | on success. |
1 | if no data is available or errors. |
Referenced by USART0_Handler(), and usart_serial_getchar().
void usart_reset | ( | Usart * | p_usart | ) |
Reset the USART and disable TX and RX.
p_usart | Pointer to a USART instance. |
References usart_disable_writeprotect(), usart_drive_DTR_pin_high(), usart_drive_RTS_pin_high(), usart_reset_rx(), usart_reset_status(), and usart_reset_tx().
Referenced by usart_init_rs232(), usart_init_spi_master(), usart_init_spi_slave(), usart_init_sync_master(), and usart_init_sync_slave().
void usart_reset_rx | ( | Usart * | p_usart | ) |
Immediately stop and disable USART receiver.
p_usart | Pointer to a USART instance. |
Referenced by usart_reset().
void usart_reset_status | ( | Usart * | p_usart | ) |
Reset status bits (PARE, OVER, MANERR, UNRE and PXBRK in US_CSR).
p_usart | Pointer to a USART instance. |
Referenced by usart_reset().
void usart_reset_tx | ( | Usart * | p_usart | ) |
Immediately stop and disable USART transmitter.
p_usart | Pointer to a USART instance. |
Referenced by usart_reset().
void usart_restart_rx_timeout | ( | Usart * | p_usart | ) |
Restart the receive timeout.
p_usart | Pointer to a USART instance. |
uint32_t usart_send_address | ( | Usart * | p_usart, |
uint32_t | ul_addr | ||
) |
In Multidrop mode only, the next character written to the US_THR is sent with the address bit set.
p_usart | Pointer to a USART instance. |
ul_addr | The address to be sent out. |
0 | on success. |
1 | on failure. |
References usart_write().
uint32_t usart_set_async_baudrate | ( | Usart * | p_usart, |
uint32_t | baudrate, | ||
uint32_t | ul_mck | ||
) |
Calculate a clock divider(CD) and a fractional part (FP) for the USART asynchronous modes to generate a baudrate as close as possible to the baudrate set point.
p_usart | Pointer to a USART instance. |
baudrate | Baud rate set point. |
ul_mck | USART module input clock frequency. |
0 | Baud rate is successfully initialized. |
1 | Baud rate set point is out of range for the given input clock frequency. |
References HIGH_FRQ_SAMPLE_DIV, LOW_FRQ_SAMPLE_DIV, and MAX_CD_VALUE.
Referenced by usart_init_rs232().
void usart_set_rx_timeout | ( | Usart * | p_usart, |
uint32_t | timeout | ||
) |
Configure the receive timeout register.
p_usart | Pointer to a USART instance. |
timeout | The value of receive timeout. |
|
static |
Calculate a clock divider (CD) for the USART SPI master mode to generate a baud rate as close as possible to the baud rate set point.
p_usart | Pointer to a USART instance. |
baudrate | Baud rate set point. |
ul_mck | USART module input clock frequency. |
0 | Baud rate is successfully initialized. |
1 | Baud rate set point is out of range for the given input clock frequency. |
References MAX_CD_VALUE.
Referenced by usart_init_spi_master().
|
static |
Select the SCK pin as the source of baudrate for the USART SPI slave mode.
p_usart | Pointer to a USART instance. |
Referenced by usart_init_spi_slave().
|
static |
Calculate a clock divider for the USART synchronous master modes to generate a baudrate as close as possible to the baudrate set point.
p_usart | Pointer to a USART instance. |
baudrate | Baud rate set point. |
ul_mck | USART module input clock frequency. |
0 | Baud rate is successfully initialized. |
1 | Baud rate set point is out of range for the given input clock frequency. |
References MAX_CD_VALUE.
Referenced by usart_init_sync_master().
|
static |
Select the SCK pin as the source of baud rate for the USART synchronous slave modes.
p_usart | Pointer to a USART instance. |
Referenced by usart_init_sync_slave().
void usart_set_tx_timeguard | ( | Usart * | p_usart, |
uint32_t | timeguard | ||
) |
Configure the transmit timeguard register.
p_usart | Pointer to a USART instance. |
timeguard | The value of transmit timeguard. |
void usart_spi_force_chip_select | ( | Usart * | p_usart | ) |
Drive the slave select line NSS (RTS pin) to 0 in SPI master mode.
p_usart | Pointer to a USART instance. |
void usart_spi_release_chip_select | ( | Usart * | p_usart | ) |
Drive the slave select line NSS (RTS pin) to 1 in SPI master mode.
p_usart | Pointer to a USART instance. |
void usart_start_rx_timeout | ( | Usart * | p_usart | ) |
Start waiting for a character before clocking the timeout count.
Reset the status bit TIMEOUT in US_CSR.
p_usart | Pointer to a USART instance. |
void usart_start_tx_break | ( | Usart * | p_usart | ) |
Start transmission of a break.
p_usart | Pointer to a USART instance. |
void usart_stop_tx_break | ( | Usart * | p_usart | ) |
Stop transmission of a break.
p_usart | Pointer to a USART instance. |
uint32_t usart_write | ( | Usart * | p_usart, |
uint32_t | c | ||
) |
Write to USART Transmit Holding Register.
p_usart | Pointer to a USART instance. |
c | Data to be sent. |
0 | on success. |
1 | on failure. |
Referenced by transmit_mode_sync(), usart_send_address(), and usart_serial_putchar().
void usart_write_line | ( | Usart * | p_usart, |
const char * | string | ||
) |
Write one-line string through USART.
p_usart | Pointer to a USART instance. |
string | Pointer to one-line string to be sent. |
References usart_putchar().