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/* *****************************************************************************
* The MIT License
*
* Copyright (c) 2010 Perry Hung.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
* ****************************************************************************/
/**
* @brief HardwareSPI "wiring-like" api for SPI
*/
/* NOTES:
*
* Speeds:
* -----------------------------------
* Interface num: SPI1 SPI2
* Bus APB2 APB1
* -----------------------------------
* Prescaler Frequencies
* -----------------------------------
* 2: N/A 18 000 000
* 4: 18 000 000 9 000 000
* 8: 9 000 000 4 500 000
* 16: 4 500 000 2 250 000
* 32: 2 250 000 1 125 000
* 64: 1 125 000 562 500
* 128: 562 500 281 250
* 256: 281 250 140 625
*
* TODO: Do the complementary PWM outputs mess up SPI2?
* */
#include "wiring.h"
#include "spi.h"
#include "HardwareSPI.h"
static const uint32 prescaleFactors[MAX_SPI_FREQS] = {
SPI_PRESCALE_2, // SPI_18MHZ
SPI_PRESCALE_4, // SPI_9MHZ
SPI_PRESCALE_8, // SPI_4_5MHZ
SPI_PRESCALE_16, // SPI_2_25MHZ
SPI_PRESCALE_32, // SPI_1_125MHZ
SPI_PRESCALE_64, // SPI_562_500KHZ
SPI_PRESCALE_128, // SPI_281_250KHZ
SPI_PRESCALE_256, // SPI_140_625KHZ
};
/**
* @brief Initialize a SPI peripheral
* @param freq frequency to run at, must one of the following values:
* - SPI_18MHZ
* - SPI_9MHZ
* - SPI_4_5MHZ
* - SPI_2_25MHZ
* - SPI_1_125MHZ
* - SPI_562_500KHZ
* - SPI_281_250KHZ
* - SPI_140_625KHZ
* @param endianness endianness of the data frame, must be either LSBFIRST
* or MSBFIRST
* @param mode SPI standard CPOL and CPHA levels
*/
void HardwareSPI::begin(SPIFrequency freq, uint32 endianness, uint32 mode) {
uint32 spi_num = this->spi_num;
uint32 high_speed = 0;
uint32 index;
uint32 prescale;
if ((freq >= MAX_SPI_FREQS) ||
!((endianness == LSBFIRST) ||
(endianness == MSBFIRST)) ||
(mode >= 4)) {
return;
}
if (spi_num == 1) {
/* SPI1 is too fast for 140625 */
if (freq == SPI_140_625KHZ) {
return;
}
/* Turn off PWM on shared pins */
timers_disable_channel(3, 2);
timers_disable_channel(3, 1);
}
endianness = (endianness == LSBFIRST) ? SPI_LSBFIRST : SPI_MSBFIRST;
prescale = (spi_num == 1) ? prescaleFactors[freq + 1] : prescaleFactors[freq];
spi_init(spi_num, prescale, endianness, 0);
}
/**
* @brief Initialize a SPI peripheral with a default speed of 1.125 MHZ, MSBFIRST,
* mode 0
* @param mode SPI standard CPOL and CPHA levels
*/
void HardwareSPI::begin(void) {
begin(SPI_1_125MHZ, MSBFIRST, 0);
}
/**
* @brief send a byte out the spi peripheral
* @param data byte to send
*/
void HardwareSPI::send(uint8 data) {
spi_tx(this->spi_num, data);
}
/**
* @brief read a byte from the spi peripheral
* @return byte in the buffer
*/
uint8 HardwareSPI::recv(void) {
return spi_rx(this->spi_num);
}
HardwareSPI::HardwareSPI(uint32 spi_num) {
this->spi_num = spi_num;
}
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