ardupilot/libraries/SPI3/SPI3.cpp

94 lines
2.3 KiB
C++

/*
* SPI3.cpp - SPI library using UART3 for Ardupilot Mega
* Code by Randy Mackay, DIYDrones.com
* but mostly based on standard Arduino SPI class by Cristian Maglie <c.maglie@bug.st>
*
* 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 2.1 of the License, or (at your option) any later version.
*
*/
#include "pins_arduino.h"
#include "SPI3.h"
SPI3Class SPI3;
bool SPI3Class::_initialised = false;
void SPI3Class::begin() {
// check if begin has been run already
if( _initialised ) {
return;
}
// Set direction register for SCK and MOSI pin.
pinMode(SPI3_SCK, OUTPUT);
pinMode(SPI3_MOSI, OUTPUT);
pinMode(SPI3_MISO, INPUT);
// Setup Serial Port3 in SPI mode (MSPI), Mode 0, Clock: 8Mhz
UBRR3 = 0;
DDRJ |= (1<<PJ2); // SPI clock XCK3 (PJ2) as output. This enable SPI Master mode
// put UART3 into SPI master mode, default mode and LSB bit order
UCSR3C = SPI3_USART_SPI_MASTER | SPI3_DEFAULT_MODE;
// Enable receiver and transmitter.
UCSR3B = (1<<RXEN3)|(1<<TXEN3);
// Set Baud rate
UBRR3 = SPI3_DEFAULT_SPEED; // SPI running at 2Mhz by default
// initialisation complete
_initialised = true;
}
// end - switch UART3 back to asyncronous UART
// Note: this is untested
void SPI3Class::end() {
uint8_t temp = UCSR3C;
// put UART3 into ASync UART mode
temp = (temp & ~SPI3_USART_MASK) | SPI3_USART_ASYNC_UART;
UCSR3C = temp;
// reinitialisation will be required
_initialised = false;
}
uint8_t SPI3Class::transfer(uint8_t data) {
/* Wait for empty transmit buffer */
while ( !( UCSR3A & (1<<UDRE3)) ) ;
/* Put data into buffer, sends the data */
UDR3 = data;
/* Wait for data to be received */
while ( !(UCSR3A & (1<<RXC3)) ) ;
/* Get and return received data from buffer */
return UDR3;
}
void SPI3Class::setBitOrder(uint8_t bitOrder)
{
if(bitOrder == SPI3_LSBFIRST) {
UCSR3C |= _BV(2);
} else {
UCSR3C &= ~(_BV(2));
}
}
void SPI3Class::setDataMode(uint8_t mode)
{
UCSR3C = (UCSR3C & ~SPI3_MODE_MASK) | mode;
}
void SPI3Class::setSpeed(uint8_t rate)
{
UBRR3 = rate;
}