111 lines
3.8 KiB
C
111 lines
3.8 KiB
C
/*
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* Copyright (c) 2016, Alex Taradov <alex@taradov.com>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*- Includes ----------------------------------------------------------------*/
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#include <stdlib.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include "samd21.h"
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#include "hal_gpio.h"
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#include "spi_master.h"
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/*- Definitions -------------------------------------------------------------*/
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HAL_GPIO_PIN(MISO, A, 4);
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HAL_GPIO_PIN(MOSI, A, 6);
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HAL_GPIO_PIN(SCLK, A, 7);
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HAL_GPIO_PIN(SS, A, 5);
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#define SPI_SERCOM SERCOM0
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#define SPI_SERCOM_PMUX PORT_PMUX_PMUXE_D_Val
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#define SPI_SERCOM_GCLK_ID SERCOM0_GCLK_ID_CORE
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#define SPI_SERCOM_CLK_GEN 0
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#define SPI_SERCOM_APBCMASK PM_APBCMASK_SERCOM0
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/*- Implementations ---------------------------------------------------------*/
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//-----------------------------------------------------------------------------
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int spi_init(int freq, int mode)
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{
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int baud = F_CPU / (2 * freq) - 1;
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if (baud < 0)
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baud = 0;
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if (baud > 255)
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baud = 255;
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freq = F_CPU / (2 * (baud + 1));
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HAL_GPIO_MISO_in();
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HAL_GPIO_MISO_pmuxen(SPI_SERCOM_PMUX);
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HAL_GPIO_MOSI_out();
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HAL_GPIO_MOSI_pmuxen(SPI_SERCOM_PMUX);
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HAL_GPIO_SCLK_out();
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HAL_GPIO_SCLK_pmuxen(SPI_SERCOM_PMUX);
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HAL_GPIO_SS_out();
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HAL_GPIO_SS_set();
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PM->APBCMASK.reg |= SPI_SERCOM_APBCMASK;
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GCLK->CLKCTRL.reg = GCLK_CLKCTRL_ID(SPI_SERCOM_GCLK_ID) |
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GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN(SPI_SERCOM_CLK_GEN);
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SPI_SERCOM->SPI.CTRLA.reg = SERCOM_SPI_CTRLA_SWRST;
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while (SPI_SERCOM->SPI.CTRLA.reg & SERCOM_SPI_CTRLA_SWRST);
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SPI_SERCOM->SPI.CTRLB.reg = SERCOM_SPI_CTRLB_RXEN;
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SPI_SERCOM->SPI.BAUD.reg = baud;
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SPI_SERCOM->SPI.CTRLA.reg = SERCOM_SPI_CTRLA_ENABLE |
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SERCOM_SPI_CTRLA_DIPO(0) | SERCOM_SPI_CTRLA_DOPO(1) |
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((mode & 1) ? SERCOM_SPI_CTRLA_CPHA : 0) |
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((mode & 2) ? SERCOM_SPI_CTRLA_CPOL : 0) |
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SERCOM_SPI_CTRLA_MODE_SPI_MASTER;
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return freq;
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}
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//-----------------------------------------------------------------------------
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void spi_ss(int state)
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{
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while (!SPI_SERCOM->SPI.INTFLAG.bit.DRE);
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HAL_GPIO_SS_write(state);
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}
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//-----------------------------------------------------------------------------
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uint8_t spi_write_byte(uint8_t byte)
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{
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SPI_SERCOM->SPI.DATA.reg = byte;
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while (!SPI_SERCOM->SPI.INTFLAG.bit.RXC);
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return SPI_SERCOM->SPI.DATA.reg;
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}
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