/** @defgroup STM32F1xx_usart_file USART

@ingroup STM32F_files

@brief <b>libopencm3 STM32F USART</b>

@version 1.0.0

@author @htmlonly &copy; @endhtmlonly 2009 Uwe Hermann <uwe@hermann-uwe.de>

@date 30 August 2012

This library supports the USART/UART in the STM32F series
of ARM Cortex Microcontrollers by ST Microelectronics.

Devices can have up to 3 USARTs and 2 UARTs.

LGPL License Terms @ref lgpl_license
 */
/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
 *
 * 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/>.
 */

/**@{*/

#include <libopencm3/stm32/usart.h>

#if defined(STM32F1)
#	include <libopencm3/stm32/f1/rcc.h>
#elif defined(STM32F2)
#	include <libopencm3/stm32/f2/rcc.h>
#elif defined(STM32F4)
#	include <libopencm3/stm32/f4/rcc.h>
#else
#	error "stm32 family not defined."
#endif

/*-----------------------------------------------------------------------------*/
/** @brief USART Set Baudrate.

The baud rate is computed from the APB high-speed prescaler clock (for USART1)
or the APB low-speed prescaler clock (for other USARTs). These values must
be correctly set before calling this function (refer to the rcc_clock_setup-*
functions in RCC).

@todo Add support for USART6 and oversampling in F2/F4

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@param[in] baud unsigned 32 bit. Baud rate specified in Hz.
*/

void usart_set_baudrate(u32 usart, u32 baud)
{
	u32 clock = rcc_ppre1_frequency;

//#ifdef STM32F1
	if (usart == USART1) {
		clock = rcc_ppre2_frequency;
	}
/* This has to be added for F2 when it get's support for USART6 */
/*
#else
	if ((usart == USART1) ||
	    (usart == USART6)) {
		clock = rcc_ppre2_frequency;
	}
#endif
*/

	/*
	 * Yes it is as simple as that. The reference manual is
	 * talking about fractional calculation but it seems to be only
	 * marketting babble to sound awesome. It is nothing else but a
	 * simple divider to generate the correct baudrate.
	 *
	 * Note: We round() the value rather than floor()ing it, for more
	 * accurate divisor selection.
	 */
	USART_BRR(usart) = ((2 * clock) + baud) / (2 * baud);
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Set Word Length.

The word length is set to 8 or 9 bits. Note that the last bit will be a parity bit
if parity is enabled, in which case the data length will be 7 or 8 bits respectively.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@param[in] bits unsigned 32 bit. Word length in bits 8 or 9.
*/

void usart_set_databits(u32 usart, u32 bits)
{
	if (bits == 8)
		USART_CR1(usart) &= ~USART_CR1_M; /* 8 data bits */
	else
		USART_CR1(usart) |= USART_CR1_M;  /* 9 data bits */
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Set Stop Bit(s).

The stop bits are specified as 0.5, 1, 1.5 or 2.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@param[in] stopbits unsigned 32 bit. Stop bits @ref usart_cr2_stopbits.
*/

void usart_set_stopbits(u32 usart, u32 stopbits)
{
	u32 reg32;

	reg32 = USART_CR2(usart);
	reg32 = (reg32 & ~USART_CR2_STOPBITS_MASK) | stopbits;
	USART_CR2(usart) = reg32;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Set Parity.

The parity bit can be selected as none, even or odd.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@param[in] parity unsigned 32 bit. Parity @ref usart_cr1_parity.
*/

void usart_set_parity(u32 usart, u32 parity)
{
	u32 reg32;

	reg32 = USART_CR1(usart);
	reg32 = (reg32 & ~USART_PARITY_MASK) | parity;
	USART_CR1(usart) = reg32;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Set Rx/Tx Mode.

The mode can be selected as Rx only, Tx only or Rx+Tx.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@param[in] mode unsigned 32 bit. Mode @ref usart_cr1_mode.
*/

void usart_set_mode(u32 usart, u32 mode)
{
	u32 reg32;

	reg32 = USART_CR1(usart);
	reg32 = (reg32 & ~USART_MODE_MASK) | mode;
	USART_CR1(usart) = reg32;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Set Hardware Flow Control.

The flow control bit can be selected as none, RTS, CTS or RTS+CTS.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@param[in] flowcontrol unsigned 32 bit. Flowcontrol @ref usart_cr3_flowcontrol.
*/

void usart_set_flow_control(u32 usart, u32 flowcontrol)
{
	u32 reg32;

	reg32 = USART_CR3(usart);
	reg32 = (reg32 & ~USART_FLOWCONTROL_MASK) | flowcontrol;
	USART_CR3(usart) = reg32;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Enable.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
*/

void usart_enable(u32 usart)
{
	USART_CR1(usart) |= USART_CR1_UE;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Disable.

At the end of the current frame, the USART is disabled to reduce power.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
*/

void usart_disable(u32 usart)
{
	USART_CR1(usart) &= ~USART_CR1_UE;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Send a Data Word.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@param[in] data unsigned 16 bit.
*/

void usart_send(u32 usart, u16 data)
{
	/* Send data. */
	USART_DR(usart) = (data & USART_DR_MASK);
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Read a Received Data Word.

If parity is enabled the MSB (bit 7 or 8 depending on the word length) is the parity bit.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@returns unsigned 16 bit data word.
*/

u16 usart_recv(u32 usart)
{
	/* Receive data. */
	return USART_DR(usart) & USART_DR_MASK;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Wait for Transmit Data Buffer Empty

Blocks until the transmit data buffer becomes empty and is ready to accept the
next data word.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
*/

void usart_wait_send_ready(u32 usart)
{
	/* Wait until the data has been transferred into the shift register. */
	while ((USART_SR(usart) & USART_SR_TXE) == 0);
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Wait for Received Data Available

Blocks until the receive data buffer holds a valid received data word.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
*/

void usart_wait_recv_ready(u32 usart)
{
	/* Wait until the data is ready to be received. */
	while ((USART_SR(usart) & USART_SR_RXNE) == 0);
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Send Data Word with Blocking

Blocks until the transmit data buffer becomes empty then writes the next data word
for transmission.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@param[in] data unsigned 16 bit.
*/

void usart_send_blocking(u32 usart, u16 data)
{
	usart_wait_send_ready(usart);
	usart_send(usart, data);
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Read a Received Data Word with Blocking.

Wait until a data word has been received then return the word.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
@returns unsigned 16 bit data word.
*/

u16 usart_recv_blocking(u32 usart)
{
	usart_wait_recv_ready(usart);

	return usart_recv(usart);
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Receiver DMA Enable.

DMA is available on:
@li USART1 Rx DMA1 channel 5.
@li USART2 Rx DMA1 channel 6.
@li USART3 Rx DMA1 channel 3.
@li UART4 Rx DMA2 channel 3.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
*/

void usart_enable_rx_dma(u32 usart)
{
	USART_CR3(usart) |= USART_CR3_DMAR;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Receiver DMA Disable.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
*/

void usart_disable_rx_dma(u32 usart)
{
	USART_CR3(usart) &= ~USART_CR3_DMAR;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Transmitter DMA Enable.

DMA is available on:
@li USART1 Tx DMA1 channel 4.
@li USART2 Tx DMA1 channel 7.
@li USART3 Tx DMA1 channel 2.
@li UART4 Tx DMA2 channel 5.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
*/

void usart_enable_tx_dma(u32 usart)
{
	USART_CR3(usart) |= USART_CR3_DMAT;
}

/*-----------------------------------------------------------------------------*/
/** @brief USART Transmitter DMA Disable.

@param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
*/

void usart_disable_tx_dma(u32 usart)
{
	USART_CR3(usart) &= ~USART_CR3_DMAT;
}


/**@}*/