lora-car/libopencm3/lib/lm4f/uart.c
Arti Zirk 054740c5de git subrepo clone https://github.com/libopencm3/libopencm3.git
subrepo:
  subdir:   "libopencm3"
  merged:   "88e91c9a7cce"
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2023-01-21 21:54:42 +02:00

628 lines
18 KiB
C

/*
* This file is part of the libopencm3 project.
*
* Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @defgroup uart_file UART
*
* @ingroup LM4Fxx
*
* @author @htmlonly &copy; @endhtmlonly 2013 Alexandru Gagniuc <mr.nuke.me@gmail.com>
*
* \brief <b>libopencm3 LM4F Universal Asynchronous Receiver Transmitter</b>
*
* The LM4F UART API provides functionality for accessing the UART hardware of
* the LM4F.
*
* Please see the individual UART modules for more details. To use the UART, the
* uart.h header needs to be included:
* @code{.c}
* #include <libopencm3/lm4f/uart.h>
* @endcode
*
* @{
*/
#include <libopencm3/lm4f/uart.h>
#include <libopencm3/lm4f/systemcontrol.h>
#include <libopencm3/lm4f/rcc.h>
/** @defgroup uart_config UART configuration
* @ingroup uart_file
*
* \brief <b>Enabling and configuring the UART</b>
*
* Enabling the UART is a two step process. The GPIO on which the UART resides
* must be enabled, and the UART pins must be configured as alternate function,
* digital pins. Pins must also be muxed to the appropriate alternate function.
* This is done with the GPIO API.
*
* The second step involves enabling and the UART itself. The UART should be
* disabled while it is being configured.
* -# The UART clock must be enabled with @ref periph_clock_enable().
* -# The UART must be disabled with @ref uart_disable().
* -# The UART clock source should be chosen before setting the baudrate.
* -# Baudrate, data bits, stop bit length, and parity can be configured.
* -# If needed, enable CTS or RTS lines via the @ref uart_set_flow_control().
* -# The UART can now be enabled with @ref uart_enable().
*
* For example, to enable UART1 at 115200 8n1 with hardware flow control:
* @code{.c}
* // Enable the UART clock
* periph_clock_enable(RCC_UART1);
* // We need a brief delay before we can access UART config registers
* __asm__("nop"); __asm__("nop"); __asm__("nop");
* // Disable the UART while we mess with its settings
* uart_disable(UART1);
* // Configure the UART clock source as precision internal oscillator
* uart_clock_from_piosc();
* // Set communication parameters
* uart_set_baudrate(UART1, 115200);
* uart_set_databits(UART1, 8);
* uart_set_parity(UART1, UART_PARITY_NONE);
* uart_set_stopbits(UART1, 1);
* // Enable RTC and CTS lines
* uart_set_flow_control(UART1, UART_FLOWCTL_HARD_RTS_CTS);
* // Now that we're done messing with the settings, enable the UART
* uart_enable(UART1);
* @endcode
*/
/**@{*/
/**
* \brief Enable the UART
*
* Enable the UART. The Rx and Tx lines are also enabled.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_enable(uint32_t uart)
{
UART_CTL(uart) |= (UART_CTL_UARTEN | UART_CTL_RXE | UART_CTL_TXE);
}
/**
* \brief Disable the UART
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_disable(uint32_t uart)
{
UART_CTL(uart) &= ~UART_CTL_UARTEN;
}
/**
* \brief Set UART baudrate
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] baud Baud rate in bits per second (bps).*
*/
void uart_set_baudrate(uint32_t uart, uint32_t baud)
{
uint32_t clock;
/* Are we running off the internal clock or system clock? */
if (UART_CC(uart) == UART_CC_CS_PIOSC) {
clock = 16000000;
} else {
clock = rcc_get_system_clock_frequency();
}
/* Find the baudrate divisor */
uint32_t div = (((clock * 8) / baud) + 1) / 2;
/* Set the baudrate divisors */
UART_IBRD(uart) = div / 64;
UART_FBRD(uart) = div % 64;
}
/**
* \brief Set UART databits
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] databits number of data bits per transmission.
*/
void uart_set_databits(uint32_t uart, uint8_t databits)
{
uint32_t reg32, bitint32_t;
/* This has the same effect as using UART_LCRH_WLEN_5/6/7/8 directly */
bitint32_t = (databits - 5) << 5;
/* TODO: What about 9 data bits? */
reg32 = UART_LCRH(uart);
reg32 &= ~UART_LCRH_WLEN_MASK;
reg32 |= bitint32_t;
UART_LCRH(uart) = reg32;
}
/**
* \brief Set UART stopbits
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] bits the requested number of stopbits, either 1 or 2.
*/
void uart_set_stopbits(uint32_t uart, uint8_t stopbits)
{
if (stopbits == 2) {
UART_LCRH(uart) |= UART_LCRH_STP2;
} else {
UART_LCRH(uart) &= ~UART_LCRH_STP2;
}
}
/**
* \brief Set UART parity
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] bits the requested parity scheme.
*/
void uart_set_parity(uint32_t uart, enum uart_parity parity)
{
uint32_t reg32;
reg32 = UART_LCRH(uart);
reg32 |= UART_LCRH_PEN;
reg32 &= ~(UART_LCRH_SPS | UART_LCRH_EPS);
switch (parity) {
case UART_PARITY_NONE:
/* Once we disable parity the other bits are meaningless */
UART_LCRH(uart) &= ~UART_LCRH_PEN;
return;
case UART_PARITY_ODD:
break;
case UART_PARITY_EVEN:
reg32 |= UART_LCRH_EPS;
break;
case UART_PARITY_STICK_0:
reg32 |= (UART_LCRH_SPS | UART_LCRH_EPS);
break;
case UART_PARITY_STICK_1:
reg32 |= UART_LCRH_SPS;
break;
}
UART_LCRH(uart) = reg32;
}
/**
* \brief Set the flow control scheme
*
* Set the flow control scheme by enabling or disabling RTS and CTS lines. This
* will only have effect if the given UART supports the RTS and CTS lines.
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] flow The flow control scheme to use (none, RTS, CTS or both) \n
* UART_FLOWCTL_RTS -- enable the RTS line \n
* UART_FLOWCTL_CTS -- enable the CTS line \n
* UART_FLOWCTL_RTS_CTS -- enable both RTS and CTS lines
*/
void uart_set_flow_control(uint32_t uart, enum uart_flowctl flow)
{
uint32_t reg32 = UART_CTL(uart);
reg32 &= ~(UART_CTL_RTSEN | UART_CTL_CTSEN);
if (flow == UART_FLOWCTL_RTS) {
reg32 |= UART_CTL_RTSEN;
} else if (flow == UART_FLOWCTL_CTS) {
reg32 |= UART_CTL_CTSEN;
} else if (flow == UART_FLOWCTL_RTS_CTS) {
reg32 |= (UART_CTL_RTSEN | UART_CTL_CTSEN);
}
UART_CTL(uart) = reg32;
}
/**
* \brief Clock the UART module from the internal oscillator
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_clock_from_piosc(uint32_t uart)
{
UART_CC(uart) = UART_CC_CS_PIOSC;
}
/**
* \brief Clock the UART module from the system clock
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_clock_from_sysclk(uint32_t uart)
{
UART_CC(uart) = UART_CC_CS_SYSCLK;
}
/**@}*/
/** @defgroup uart_send_recv UART transmission and reception
* @ingroup uart_file
*
* \brief <b>Sending and receiving data through the UART</b>
*
* Primitives for sending and receiving data are provided, @ref uart_send() and
* @ref uart_recv(). These primitives do not check if data can be transmitted
* or wait for data. If waiting until data is available or can be transmitted is
* desired, blocking primitives are also available, @ref uart_send_blocking()
* and @ref uart_recv_blocking().
*
* These primitives only handle one byte at at time, and thus may be unsuited
* for some applications. You may also consider using @ref uart_dma.
*/
/**@{*/
/**
* \brief UART Send a Data Word.
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] data data to send.
*/
void uart_send(uint32_t uart, uint16_t data)
{
data &= 0xFF;
UART_DR(uart) = data;
}
/**
* \brief UART Read a Received Data Word.
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @return data from the Rx FIFO.
*/
uint16_t uart_recv(uint32_t uart)
{
return UART_DR(uart) & UART_DR_DATA_MASK;
}
/**
* \brief UART Wait for Transmit Data Buffer Not Full
*
* Blocks until the transmit data FIFO is not empty and can accept the next data
* word.
* \n
* Even if the FIFO is not empty, this function will return as long as there is
* room for at least one more word.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_wait_send_ready(uint32_t uart)
{
/* Wait until the Tx FIFO is no longer full */
while (UART_FR(uart) & UART_FR_TXFF);
}
/**
* \brief UART Wait for Received Data Available
*
* Blocks until the receive data FIFO holds a at least valid received data word.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_wait_recv_ready(uint32_t uart)
{
/* Wait until the Tx FIFO is no longer empty */
while (UART_FR(uart) & UART_FR_RXFE);
}
/**
* \brief UART Send Data Word with Blocking
*
* Blocks until the transmit data FIFO can accept the next data word for
* transmission.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_send_blocking(uint32_t uart, uint16_t data)
{
uart_wait_send_ready(uart);
uart_send(uart, data);
}
/**
* \brief UART Read a Received Data Word with Blocking.
*
* Wait until a data word has been received then return the word.
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @return data from the Rx FIFO.
*/
uint16_t uart_recv_blocking(uint32_t uart)
{
uart_wait_recv_ready(uart);
return uart_recv(uart);
}
/**@}*/
/** @defgroup uart_irq UART Interrupt control
* @ingroup uart_file
*
* \brief <b>Configuring interrupts from the UART</b>
*
* To have an event generate an interrupt, its interrupt source must be
* unmasked. This can be achieved with @ref uart_enable_interrupts(). Interrupts
* which are no longer needed can be disabled through
* @ref uart_disable_interrupts().
*
* In order for the interrupt to generate an IRQ and a call to the interrupt
* service routine, the interrupt for the target UART must be routed through the
* NVIC with @ref nvic_enable_irq(). For this last step, the nvic.h header is
* needed:
* @code{.c}
* #include <libopencm3/lm4f/nvic.h>
* @endcode
*
* Enabling an interrupt is as simple as unmasking the desired interrupt, and
* routing the desired UART's interrupt through the NVIC.
* @code{.c}
* // Unmask receive interrupt
* uart_enable_rx_interrupt(UART0);
* // Make sure the interrupt is routed through the NVIC
* nvic_enable_irq(NVIC_UART0_IRQ);
* @endcode
*
* If a more than one interrupt is to be enabled at one time, the interrupts
* can be enabled by a single call to @ref uart_enable_interrupts().
* For example:
* @code{.c}
* // Unmask receive, CTS, and RI, interrupts
* uart_enable_interrupts(UART0, UART_INT_RX | UART_INT_RI | UART_INT_CTS);
* @endcode
*
* After interrupts are properly enabled and routed through the NVIC, when an
* event occurs, the appropriate IRQ flag is set by hardware, and execution
* jumps to the UART ISR. The ISR should query the IRQ flags to determine which
* event caused the interrupt. For this, use @ref uart_is_interrupt_source(),
* with the desired UART_INT flag. After one or more interrupt sources are
* serviced, the IRQ flags must be cleared by the ISR. This can be done with
* @ref uart_clear_interrupt_flag().
*
* A typical UART ISR may look like the following:
* @code{.c}
* void uart0_isr(void)
* {
* uint32_t serviced_irqs = 0;
*
* // Process individual IRQs
* if (uart_is_interrupt_source(UART0, UART_INT_RX)) {
* process_rx_event();
* serviced_irq |= UART_INT_RX;
* }
* if (uart_is_interrupt_source(UART0, UART_INT_CTS)) {
* process_cts_event();
* serviced_irq |= UART_INT_CTS;
* }
*
* // Clear the interrupt flag for the processed IRQs
* uart_clear_interrupt_flag(UART0, serviced_irqs);
* }
* @endcode
*/
/**@{*/
/**
* \brief Enable Specific UART Interrupts
*
* Enable any combination of interrupts. Interrupts may be OR'ed together to
* enable them with one call. For example, to enable both the RX and CTS
* interrupts, pass (UART_INT_RX | UART_INT_CTS)
*
* Note that the NVIC must be enabled and properly configured for the interrupt
* to be routed to the CPU.
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] ints Interrupts which to enable. Any combination of interrupts may
* be specified by OR'ing then together
*/
void uart_enable_interrupts(uint32_t uart, enum uart_interrupt_flag ints)
{
UART_IM(uart) |= ints;
}
/**
* \brief Enable Specific UART Interrupts
*
* Disabe any combination of interrupts. Interrupts may be OR'ed together to
* disable them with one call. For example, to disable both the RX and CTS
* interrupts, pass (UART_INT_RX | UART_INT_CTS)
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] ints Interrupts which to disable. Any combination of interrupts
* may be specified by OR'ing then together
*/
void uart_disable_interrupts(uint32_t uart, enum uart_interrupt_flag ints)
{
UART_IM(uart) &= ~ints;
}
/**
* \brief Enable the UART Receive Interrupt.
*
* Note that the NVIC must be enabled and properly configured for the interrupt
* to be routed to the CPU.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_enable_rx_interrupt(uint32_t uart)
{
uart_enable_interrupts(uart, UART_INT_RX);
}
/**
* \brief Disable the UART Receive Interrupt.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_disable_rx_interrupt(uint32_t uart)
{
uart_disable_interrupts(uart, UART_INT_RX);
}
/**
* \brief Enable the UART Transmit Interrupt.
*
* Note that the NVIC must be enabled and properly configured for the interrupt
* to be routed to the CPU.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_enable_tx_interrupt(uint32_t uart)
{
uart_enable_interrupts(uart, UART_INT_TX);
}
/**
* \brief Disable the UART Transmit Interrupt.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_disable_tx_interrupt(uint32_t uart)
{
uart_disable_interrupts(uart, UART_INT_TX);
}
/**
* \brief Mark interrupt as serviced
*
* After an interrupt is services, its flag must be cleared. If the flag is not
* cleared, then execution will jump back to the start of the ISR after the ISR
* returns.
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] ints Interrupts which to clear. Any combination of interrupts may
* be specified by OR'ing then together
*/
void uart_clear_interrupt_flag(uint32_t uart, enum uart_interrupt_flag ints)
{
UART_ICR(uart) |= ints;
}
/**@}*/
/** @defgroup uart_dma UART DMA control
* @ingroup uart_file
*
* \brief <b>Enabling Direct Memory Access transfers for the UART</b>
*
*/
/**@{*/
/**
* \brief Enable the UART Receive DMA.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_enable_rx_dma(uint32_t uart)
{
UART_DMACTL(uart) |= UART_DMACTL_RXDMAE;
}
/**
* \brief Disable the UART Receive DMA.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_disable_rx_dma(uint32_t uart)
{
UART_DMACTL(uart) &= ~UART_DMACTL_RXDMAE;
}
/**
* \brief Enable the UART Transmit DMA.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_enable_tx_dma(uint32_t uart)
{
UART_DMACTL(uart) |= UART_DMACTL_TXDMAE;
}
/**
* \brief Disable the UART Transmit DMA.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_disable_tx_dma(uint32_t uart)
{
UART_DMACTL(uart) &= ~UART_DMACTL_TXDMAE;
}
/**@}*/
/** @defgroup uart_fifo UART FIFO control
* @ingroup uart_file
*
* \brief <b>Enabling and controlling UART FIFO</b>
*
* The UART on the LM4F can either be used with a single character TX and RX
* buffer, or with a 8 character TX and RX FIFO. In order to use the FIFO it
* must be enabled, this is done with uart_enable_fifo() and can be disabled
* again with uart_disable_fifo(). On reset the FIFO is disabled, and it must
* be explicitly be enabled.
*
* When enabling the UART FIFOs, RX and TX interrupts are triggered according
* to the amount of data in the FIFOs. For the RX FIFO the trigger level is
* defined by how full the FIFO is. The TX FIFO trigger level is defined by
* how empty the FIFO is instead.
*
* For example, to enable the FIFOs and trigger interrupts for a single
* received and single transmitted character:
* @code{.c}
* uart_enable_fifo(UART0);
* uart_set_fifo_trigger_levels(UART0, UART_FIFO_RX_TRIG_1_8,
* UART_FIFO_TX_TRIG_7_8);
* @endcode
*/
/**@{*/
/**
* \brief Enable FIFO for the UART.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_enable_fifo(uint32_t uart)
{
UART_LCRH(uart) |= UART_LCRH_FEN;
}
/**
* \brief Disable FIFO for the UART.
*
* @param[in] uart UART block register address base @ref uart_reg_base
*/
void uart_disable_fifo(uint32_t uart)
{
UART_LCRH(uart) &= ~UART_LCRH_FEN;
}
/**
* \brief Set the FIFO trigger levels.
*
* @param[in] uart UART block register address base @ref uart_reg_base
* @param[in] rx_level Trigger level for RX FIFO
* @param[in] tx_level Trigger level for TX FIFO
*/
void uart_set_fifo_trigger_levels(uint32_t uart,
enum uart_fifo_rx_trigger_level rx_level,
enum uart_fifo_tx_trigger_level tx_level)
{
UART_IFLS(uart) = rx_level | tx_level;
}
/**@}*/
/**
* @}
*/