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/** @addtogroup spi_file
@author @htmlonly © @endhtmlonly 2009
Uwe Hermann <uwe@hermann-uwe.de>
@author @htmlonly © @endhtmlonly 2012
Ken Sarkies <ksarkies@internode.on.net>
Devices can have up to three SPI peripherals. The common 4-wire full-duplex
mode of operation is supported, along with 3-wire variants using unidirectional
communication modes or half-duplex bidirectional communication. A variety of
options allows many of the SPI variants to be supported. Multimaster operation
is also supported. A CRC can be generated and checked in hardware.
@note Some JTAG pins need to be remapped if SPI is to be used.
@note The I2S protocol shares the SPI hardware so the two protocols cannot be
used at the same time on the same peripheral.
Example: 1Mbps, positive clock polarity, leading edge trigger, 8-bit words,
LSB first.
@code
spi_init_master(SPI1, 1000000, SPI_CR1_CPOL_CLK_TO_0_WHEN_IDLE,
SPI_CR1_CPHA_CLK_TRANSITION_1, SPI_CR1_DFF_8BIT,
SPI_CR1_LSBFIRST);
spi_write(SPI1, 0x55); // 8-bit write
spi_write(SPI1, 0xaa88); // 16-bit write
reg8 = spi_read(SPI1); // 8-bit read
reg16 = spi_read(SPI1); // 16-bit read
@endcode
@todo need additional functions to aid ISRs in retrieving status
*/
/*
* 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/spi.h>
#include <libopencm3/stm32/rcc.h>
/*
* SPI and I2S code.
*
* Examples:
* spi_init_master(SPI1, 1000000, SPI_CR1_CPOL_CLK_TO_0_WHEN_IDLE,
* SPI_CR1_CPHA_CLK_TRANSITION_1, SPI_CR1_DFF_8BIT,
* SPI_CR1_LSBFIRST);
* spi_write(SPI1, 0x55); // 8-bit write
* spi_write(SPI1, 0xaa88); // 16-bit write
* reg8 = spi_read(SPI1); // 8-bit read
* reg16 = spi_read(SPI1); // 16-bit read
*/
/**@{*/
/*---------------------------------------------------------------------------*/
/** @brief Configure the SPI as Master.
The SPI peripheral is configured as a master with communication parameters
baudrate, data format 8/16 bits, frame format lsb/msb first, clock polarity
and phase. The SPI enable, CRC enable and CRC next controls are not affected.
These must be controlled separately.
@todo NSS pin handling.
@param[in] spi Unsigned int32. SPI peripheral identifier @ref spi_reg_base.
@param[in] br Unsigned int32. Baudrate @ref spi_baudrate.
@param[in] cpol Unsigned int32. Clock polarity @ref spi_cpol.
@param[in] cpha Unsigned int32. Clock Phase @ref spi_cpha.
@param[in] dff Unsigned int32. Data frame format 8/16 bits @ref spi_dff.
@param[in] lsbfirst Unsigned int32. Frame format lsb/msb first @ref
spi_lsbfirst.
@returns int. Error code.
*/
int spi_init_master(uint32_t spi, uint32_t br, uint32_t cpol, uint32_t cpha,
uint32_t dff, uint32_t lsbfirst)
{
uint32_t reg32 = SPI_CR1(spi);
/* Reset all bits omitting SPE, CRCEN and CRCNEXT bits. */
reg32 &= SPI_CR1_SPE | SPI_CR1_CRCEN | SPI_CR1_CRCNEXT;
reg32 |= SPI_CR1_MSTR; /* Configure SPI as master. */
reg32 |= br; /* Set baud rate bits. */
reg32 |= cpol; /* Set CPOL value. */
reg32 |= cpha; /* Set CPHA value. */
reg32 |= dff; /* Set data format (8 or 16 bits). */
reg32 |= lsbfirst; /* Set frame format (LSB- or MSB-first). */
/* TODO: NSS pin handling. */
SPI_CR1(spi) = reg32;
return 0; /* TODO */
}
/*---------------------------------------------------------------------------*/
/** @brief SPI Set Data Frame Format to 8 bits
@param[in] spi Unsigned int32. SPI peripheral identifier @ref spi_reg_base.
*/
void spi_set_dff_8bit(uint32_t spi)
{
SPI_CR1(spi) &= ~SPI_CR1_DFF;
}
/*---------------------------------------------------------------------------*/
/** @brief SPI Set Data Frame Format to 16 bits
@param[in] spi Unsigned int32. SPI peripheral identifier @ref spi_reg_base.
*/
void spi_set_dff_16bit(uint32_t spi)
{
SPI_CR1(spi) |= SPI_CR1_DFF;
}
/**@}*/
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