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