359 lines
9.9 KiB
C
359 lines
9.9 KiB
C
/** @defgroup STM32F1xx_usart_file USART
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@ingroup STM32F_files
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@brief <b>libopencm3 STM32F USART</b>
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@version 1.0.0
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@author @htmlonly © @endhtmlonly 2009 Uwe Hermann <uwe@hermann-uwe.de>
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@date 30 August 2012
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This library supports the USART/UART in the STM32F series
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of ARM Cortex Microcontrollers by ST Microelectronics.
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Devices can have up to 3 USARTs and 2 UARTs.
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LGPL License Terms @ref lgpl_license
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*/
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/*
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* This file is part of the libopencm3 project.
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*
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* Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**@{*/
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#include <libopencm3/stm32/usart.h>
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#if defined(STM32F1)
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# include <libopencm3/stm32/f1/rcc.h>
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#elif defined(STM32F2)
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# include <libopencm3/stm32/f2/rcc.h>
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#elif defined(STM32F4)
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# include <libopencm3/stm32/f4/rcc.h>
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#else
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# error "stm32 family not defined."
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#endif
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Set Baudrate.
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The baud rate is computed from the APB high-speed prescaler clock (for USART1)
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or the APB low-speed prescaler clock (for other USARTs). These values must
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be correctly set before calling this function (refer to the rcc_clock_setup-*
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functions in RCC).
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@todo Add support for USART6 and oversampling in F2/F4
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@param[in] baud unsigned 32 bit. Baud rate specified in Hz.
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*/
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void usart_set_baudrate(u32 usart, u32 baud)
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{
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u32 clock = rcc_ppre1_frequency;
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//#ifdef STM32F1
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if (usart == USART1) {
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clock = rcc_ppre2_frequency;
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}
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/* This has to be added for F2 when it get's support for USART6 */
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/*
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#else
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if ((usart == USART1) ||
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(usart == USART6)) {
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clock = rcc_ppre2_frequency;
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}
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#endif
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*/
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/*
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* Yes it is as simple as that. The reference manual is
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* talking about fractional calculation but it seems to be only
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* marketting babble to sound awesome. It is nothing else but a
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* simple divider to generate the correct baudrate.
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*
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* Note: We round() the value rather than floor()ing it, for more
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* accurate divisor selection.
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*/
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USART_BRR(usart) = ((2 * clock) + baud) / (2 * baud);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Set Word Length.
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The word length is set to 8 or 9 bits. Note that the last bit will be a parity bit
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if parity is enabled, in which case the data length will be 7 or 8 bits respectively.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@param[in] bits unsigned 32 bit. Word length in bits 8 or 9.
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*/
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void usart_set_databits(u32 usart, u32 bits)
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{
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if (bits == 8)
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USART_CR1(usart) &= ~USART_CR1_M; /* 8 data bits */
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else
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USART_CR1(usart) |= USART_CR1_M; /* 9 data bits */
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Set Stop Bit(s).
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The stop bits are specified as 0.5, 1, 1.5 or 2.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@param[in] stopbits unsigned 32 bit. Stop bits @ref usart_cr2_stopbits.
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*/
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void usart_set_stopbits(u32 usart, u32 stopbits)
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{
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u32 reg32;
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reg32 = USART_CR2(usart);
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reg32 = (reg32 & ~USART_CR2_STOPBITS_MASK) | stopbits;
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USART_CR2(usart) = reg32;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Set Parity.
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The parity bit can be selected as none, even or odd.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@param[in] parity unsigned 32 bit. Parity @ref usart_cr1_parity.
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*/
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void usart_set_parity(u32 usart, u32 parity)
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{
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u32 reg32;
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reg32 = USART_CR1(usart);
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reg32 = (reg32 & ~USART_PARITY_MASK) | parity;
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USART_CR1(usart) = reg32;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Set Rx/Tx Mode.
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The mode can be selected as Rx only, Tx only or Rx+Tx.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@param[in] mode unsigned 32 bit. Mode @ref usart_cr1_mode.
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*/
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void usart_set_mode(u32 usart, u32 mode)
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{
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u32 reg32;
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reg32 = USART_CR1(usart);
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reg32 = (reg32 & ~USART_MODE_MASK) | mode;
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USART_CR1(usart) = reg32;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Set Hardware Flow Control.
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The flow control bit can be selected as none, RTS, CTS or RTS+CTS.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@param[in] flowcontrol unsigned 32 bit. Flowcontrol @ref usart_cr3_flowcontrol.
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*/
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void usart_set_flow_control(u32 usart, u32 flowcontrol)
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{
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u32 reg32;
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reg32 = USART_CR3(usart);
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reg32 = (reg32 & ~USART_FLOWCONTROL_MASK) | flowcontrol;
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USART_CR3(usart) = reg32;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Enable.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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*/
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void usart_enable(u32 usart)
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{
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USART_CR1(usart) |= USART_CR1_UE;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Disable.
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At the end of the current frame, the USART is disabled to reduce power.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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*/
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void usart_disable(u32 usart)
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{
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USART_CR1(usart) &= ~USART_CR1_UE;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Send a Data Word.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@param[in] data unsigned 16 bit.
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*/
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void usart_send(u32 usart, u16 data)
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{
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/* Send data. */
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USART_DR(usart) = (data & USART_DR_MASK);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Read a Received Data Word.
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If parity is enabled the MSB (bit 7 or 8 depending on the word length) is the parity bit.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@returns unsigned 16 bit data word.
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*/
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u16 usart_recv(u32 usart)
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{
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/* Receive data. */
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return USART_DR(usart) & USART_DR_MASK;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Wait for Transmit Data Buffer Empty
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Blocks until the transmit data buffer becomes empty and is ready to accept the
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next data word.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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*/
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void usart_wait_send_ready(u32 usart)
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{
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/* Wait until the data has been transferred into the shift register. */
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while ((USART_SR(usart) & USART_SR_TXE) == 0);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Wait for Received Data Available
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Blocks until the receive data buffer holds a valid received data word.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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*/
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void usart_wait_recv_ready(u32 usart)
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{
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/* Wait until the data is ready to be received. */
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while ((USART_SR(usart) & USART_SR_RXNE) == 0);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Send Data Word with Blocking
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Blocks until the transmit data buffer becomes empty then writes the next data word
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for transmission.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@param[in] data unsigned 16 bit.
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*/
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void usart_send_blocking(u32 usart, u16 data)
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{
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usart_wait_send_ready(usart);
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usart_send(usart, data);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Read a Received Data Word with Blocking.
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Wait until a data word has been received then return the word.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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@returns unsigned 16 bit data word.
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*/
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u16 usart_recv_blocking(u32 usart)
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{
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usart_wait_recv_ready(usart);
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return usart_recv(usart);
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Receiver DMA Enable.
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DMA is available on:
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@li USART1 Rx DMA1 channel 5.
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@li USART2 Rx DMA1 channel 6.
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@li USART3 Rx DMA1 channel 3.
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@li UART4 Rx DMA2 channel 3.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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*/
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void usart_enable_rx_dma(u32 usart)
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{
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USART_CR3(usart) |= USART_CR3_DMAR;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Receiver DMA Disable.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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*/
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void usart_disable_rx_dma(u32 usart)
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{
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USART_CR3(usart) &= ~USART_CR3_DMAR;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Transmitter DMA Enable.
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DMA is available on:
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@li USART1 Tx DMA1 channel 4.
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@li USART2 Tx DMA1 channel 7.
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@li USART3 Tx DMA1 channel 2.
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@li UART4 Tx DMA2 channel 5.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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*/
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void usart_enable_tx_dma(u32 usart)
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{
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USART_CR3(usart) |= USART_CR3_DMAT;
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}
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/*-----------------------------------------------------------------------------*/
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/** @brief USART Transmitter DMA Disable.
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@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
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*/
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void usart_disable_tx_dma(u32 usart)
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{
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USART_CR3(usart) &= ~USART_CR3_DMAT;
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}
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/**@}*/
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