LT_SPI
LT_SPI.cpp
- Committer:
- roger5641
- Date:
- 2017-11-12
- Revision:
- 0:516e11acba42
File content as of revision 0:516e11acba42:
//! @todo Review this document. /*! LT_SPI: Routines to communicate with ATmega328P's hardware SPI port. @verbatim LT_SPI implements the low level master SPI bus routines using the hardware SPI port. SPI Frequency = (CPU Clock frequency)/(16+2(TWBR)*Prescaler) SPCR = SPI Control Register (SPIE SPE DORD MSTR CPOL CPHA SPR1 SPR0) SPSR = SPI Status Register (SPIF WCOL - - - - - SPI2X) Data Modes: CPOL CPHA Leading Edge Trailing Edge 0 0 sample rising setup falling 0 1 setup rising sample falling 1 0 sample falling setup rising 1 1 sample rising setup rising CPU Frequency = 16MHz on Arduino Uno SCK Frequency SPI2X SPR1 SPR0 Frequency Uno_Frequency 0 0 0 fosc/4 4 MHz 0 0 1 fosc/16 1 MHz 0 1 0 fosc/64 250 kHz 0 1 1 fosc/128 125 kHz 0 0 0 fosc/2 8 MHz 0 0 1 fosc/8 2 MHz 0 1 0 fosc/32 500 kHz @endverbatim REVISION HISTORY $Revision: 6237 $ $Date: 2016-12-20 15:09:16 -0800 (Tue, 20 Dec 2016) $ Copyright (c) 2013, Linear Technology Corp.(LTC) All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. The views and conclusions contained in the software and documentation are those of the authors and should not be interpreted as representing official policies, either expressed or implied, of Linear Technology Corp. The Linear Technology Linduino is not affiliated with the official Arduino team. However, the Linduino is only possible because of the Arduino team's commitment to the open-source community. Please, visit http://www.arduino.cc and http://store.arduino.cc , and consider a purchase that will help fund their ongoing work. */ //! @ingroup Linduino //! @{ //! @defgroup LT_SPI LT_SPI: Routines to communicate with ATmega328P's hardware SPI port. //! @} /*! @file @ingroup LT_SPI Library for LT_SPI: Routines to communicate with ATmega328P's hardware SPI port. */ #include <stdint.h> #include "LT_SPI.h" //DigitalOut QUIKEVAL_GPIO D9; //!< Linduino QuikEval GPIO pin (QuikEval connector pin 14) connects to Arduino pin 9 //DigitalOut QUIKEVAL_CS A3; //!< QuikEval CS pin (SPI chip select on QuikEval connector pin 6) connects to Arduino SS pin. //DigitalInOut QUIKEVAL_MUX_MODE_PIN(8,output); /*!< QUIKEVAL_MUX_MODE_PIN defines the control pin for the QuikEval MUX. //The I2C port's SCL and the SPI port's SCK signals share the same pin on the Linduino's QuikEval connector. //Additionally, the I2C port's SDA and the SPI port's MOSI signals share the same pin on the Linduino's QuikEval connector. //The pair of pins connected to the QuikEval connector is switched using a MUX on the Linduino board. //The control pin to switch the MUX is defined as QUIKEVAL_MUX_MODE_PIN (Arduino pin 8). */ void output_low(uint8_t pin) { pin = 0; } void output_high(uint8_t pin) { pin = 1; } // Reads and sends a byte // Return 0 if successful, 1 if failed void spi_transfer_byte(uint8_t cs_pin, uint8_t tx, uint8_t *rx) { output_low(cs_pin); //! 1) Pull CS low *rx = spi.write(tx); //! 2) Read byte and send byte output_high(cs_pin); //! 3) Pull CS high } // Reads and sends a word // Return 0 if successful, 1 if failed void spi_transfer_word(uint8_t cs_pin, uint16_t tx, uint16_t *rx) { union { uint8_t b[2]; uint16_t w; } data_tx; union { uint8_t b[2]; uint16_t w; } data_rx; data_tx.w = tx; output_low(cs_pin); //! 1) Pull CS low data_rx.b[1] = spi.write(data_tx.b[1]); //! 2) Read MSB and send MSB data_rx.b[0] = spi.write(data_tx.b[0]); //! 3) Read LSB and send LSB *rx = data_rx.w; output_high(cs_pin); //! 4) Pull CS high } // Reads and sends a byte array void spi_transfer_block(uint8_t cs_pin, uint8_t *tx, uint8_t *rx, uint8_t length) { int8_t i; output_low(cs_pin); //! 1) Pull CS low for (i=(length-1); i >= 0; i--) rx[i] = spi.write(tx[i]); //! 2) Read and send byte array output_high(cs_pin); //! 3) Pull CS high } // Connect SPI pins to QuikEval connector through the Linduino MUX. This will disconnect I2C. //void quikeval_SPI_connect() //{ // output_high(QUIKEVAL_CS); //! 1) Pull Chip Select High // // //! 2) Enable Main SPI // pinMode(QUIKEVAL_MUX_MODE_PIN, OUTPUT); // QUIKEVAL_MUX_MODE_PIN = 0; //} // Configure the SPI port for 4MHz SCK. // This function or spi_enable() must be called // before using the other SPI routines. //void quikeval_SPI_init(void) // Initializes SPI //{ // spi_enable(SPI_CLOCK_DIV16); //! 1) Configure the spi port for 4MHz SCK //} // Setup the processor for hardware SPI communication. // Must be called before using the other SPI routines. // Alternatively, call quikeval_SPI_connect(), which automatically // calls this function. void spi_enable(void) // Configures SCK frequency. Use constant defined in header file. { //pinMode(SCK, OUTPUT); //! 1) Setup SCK as output //pinMode(MOSI, OUTPUT); //! 2) Setup MOSI as output //pinMode(QUIKEVAL_CS, OUTPUT); //! 3) Setup CS as output spi.format(16,3); spi.frequency(1000000); } // Disable the SPI hardware port //void spi_disable() //{ // spi.end(); //} // Write a data byte using the SPI hardware //void spi_write(int8_t data) // Byte to be written to SPI port //{ // SPDR = data; //! 1) Start the SPI transfer // while (!(SPSR & _BV(SPIF))); //! 2) Wait until transfer complete //} // Read and write a data byte using the SPI hardware // Returns the data byte read //int8_t spi_read(int8_t data) //!The data byte to be written //{ // SPDR = data; //! 1) Start the SPI transfer // while (!(SPSR & _BV(SPIF))); //! 2) Wait until transfer complete // return SPDR; //! 3) Return the data read //} // Below are implementations of spi_read, etc. that do not use the // Arduino SPI library. To use these functions, uncomment them and comment out // the correcsponding function above. // // // Reads and sends a byte // // Return 0 if successful, 1 if failed // uint8_t spi_transfer_byte(uint8_t cs_pin, uint8_t tx, uint8_t *rx) // { // output_low(cs_pin); //! 1) Pull CS low // // *rx = spi_read(tx); //! 2) Read byte and send byte // // output_high(cs_pin); //! 3) Pull CS high // // return(0); // } // // // Reads and sends a word // // Return 0 if successful, 1 if failed // uint8_t spi_transfer_word(uint8_t cs_pin, uint16_t tx, uint16_t *rx) // { // union // { // uint8_t b[2]; // uint16_t w; // } data_tx; // // union // { // uint8_t b[2]; // uint16_t w; // } data_rx; // // data_tx.w = tx; // // output_low(cs_pin); //! 1) Pull CS low // // data_rx.b[1] = spi_read(data_tx.b[1]); //! 2) Read MSB and send MSB // data_rx.b[0] = spi_read(data_tx.b[0]); //! 3) Read LSB and send LSB // *rx = data_rx.w; // // output_high(cs_pin); //! 4) Pull CS high // // return(0); // } // // // Reads and sends a byte array // // Return 0 if successful, 1 if failed // uint8_t spi_transfer_block(uint8_t cs_pin, uint8_t *tx, uint8_t *rx, uint8_t length) // { // int8_t i; // // output_low(cs_pin); //! 1) Pull CS low // // for(i=0; i < length; i++) // rx[i] = spi_read(tx[i]); //! 2) Read and send byte array // // output_high(cs_pin); //! 3) Pull CS high // // return(0); // } // // // Connect SPI pins to QuikEval connector through the Linduino MUX. This will disconnect I2C. // void quikeval_SPI_connect() // { // output_high(QUIKEVAL_CS); //! 1) Pull Chip Select High // // //! 2) Enable Main SPI // pinMode(QUIKEVAL_MUX_MODE_PIN, OUTPUT); // digitalWrite(QUIKEVAL_MUX_MODE_PIN, LOW); // } // // // Configure the SPI port for 4MHz SCK. // // This function or spi_enable() must be called // // before using the other SPI routines. // void quikeval_SPI_init(void) // Initializes SPI // { // spi_enable(SPI_CLOCK_DIV32); //! 2) Configure the spi port for 4MHz SCK // } // // // Setup the processor for hardware SPI communication. // // Must be called before using the other SPI routines. // // Alternatively, call quikeval_SPI_connect(), which automatically // // calls this function. // void spi_enable(uint8_t spi_clock_divider) // Configures SCK frequency. Use constant defined in header file. // { // pinMode(SCK, OUTPUT); //! 1) Setup SCK as output // pinMode(MOSI, OUTPUT); //! 2) Setup MOSI as output // pinMode(QUIKEVAL_CS, OUTPUT); //! 3) Setup CS as output // output_low(SCK); // output_low(MOSI); // output_high(QUIKEVAL_CS); // SPCR |= _BV(MSTR); //! 4) Set the SPI port to master mode // //! 5) Set the SPI hardware rate // SPCR = (SPCR & ~SPI_CLOCK_MASK) | (spi_clock_divider & SPI_CLOCK_MASK); // SPSR = (SPSR & ~SPI_2XCLOCK_MASK) | ((spi_clock_divider >> 2) & SPI_2XCLOCK_MASK); // SPCR |= _BV(SPE); //! 5) Enable the SPI port // } // // // Disable the SPI hardware port // void spi_disable() // { // SPCR &= ~_BV(SPE); // }