mirror of
https://github.com/DCC-EX/CommandStation-EX.git
synced 2024-12-23 21:01:25 +01:00
199 lines
8.4 KiB
C
199 lines
8.4 KiB
C
/*
|
|
* © 2021, Neil McKechnie. All rights reserved.
|
|
*
|
|
* This file is part of CommandStation-EX
|
|
*
|
|
* This is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation, either version 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* It is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#ifndef I2CMANAGER_AVR_H
|
|
#define I2CMANAGER_AVR_H
|
|
|
|
#include <Arduino.h>
|
|
#include "I2CManager.h"
|
|
|
|
#include <avr/io.h>
|
|
#include <avr/interrupt.h>
|
|
|
|
/****************************************************************************
|
|
TWI State codes
|
|
****************************************************************************/
|
|
// General TWI Master staus codes
|
|
#define TWI_START 0x08 // START has been transmitted
|
|
#define TWI_REP_START 0x10 // Repeated START has been transmitted
|
|
#define TWI_ARB_LOST 0x38 // Arbitration lost
|
|
|
|
// TWI Master Transmitter staus codes
|
|
#define TWI_MTX_ADR_ACK 0x18 // SLA+W has been tramsmitted and ACK received
|
|
#define TWI_MTX_ADR_NACK 0x20 // SLA+W has been tramsmitted and NACK received
|
|
#define TWI_MTX_DATA_ACK 0x28 // Data byte has been tramsmitted and ACK received
|
|
#define TWI_MTX_DATA_NACK 0x30 // Data byte has been tramsmitted and NACK received
|
|
|
|
// TWI Master Receiver staus codes
|
|
#define TWI_MRX_ADR_ACK 0x40 // SLA+R has been tramsmitted and ACK received
|
|
#define TWI_MRX_ADR_NACK 0x48 // SLA+R has been tramsmitted and NACK received
|
|
#define TWI_MRX_DATA_ACK 0x50 // Data byte has been received and ACK tramsmitted
|
|
#define TWI_MRX_DATA_NACK 0x58 // Data byte has been received and NACK tramsmitted
|
|
|
|
// TWI Miscellaneous status codes
|
|
#define TWI_NO_STATE 0xF8 // No relevant state information available
|
|
#define TWI_BUS_ERROR 0x00 // Bus error due to an illegal START or STOP condition
|
|
|
|
#define TWI_TWBR ((F_CPU / I2C_FREQ) - 16) / 2 // TWI Bit rate Register setting.
|
|
|
|
#if defined(I2C_USE_INTERRUPTS)
|
|
#define ENABLE_TWI_INTERRUPT (1<<TWIE)
|
|
#else
|
|
#define ENABLE_TWI_INTERRUPT 0
|
|
#endif
|
|
|
|
/***************************************************************************
|
|
* Set I2C clock speed register.
|
|
***************************************************************************/
|
|
void I2CManagerClass::I2C_setClock(unsigned long i2cClockSpeed) {
|
|
TWBR = ((F_CPU / i2cClockSpeed) - 16) / 2;
|
|
}
|
|
|
|
/***************************************************************************
|
|
* Initialise I2C registers.
|
|
***************************************************************************/
|
|
void I2CManagerClass::I2C_init()
|
|
{
|
|
TWSR = 0;
|
|
TWBR = TWI_TWBR; // Set bit rate register (Baudrate). Defined in header file.
|
|
TWDR = 0xFF; // Default content = SDA released.
|
|
TWCR = (1<<TWINT); // Clear interrupt flag
|
|
|
|
pinMode(SDA, INPUT_PULLUP);
|
|
pinMode(SCL, INPUT_PULLUP);
|
|
}
|
|
|
|
/***************************************************************************
|
|
* Initiate a start bit for transmission.
|
|
***************************************************************************/
|
|
void I2CManagerClass::I2C_sendStart() {
|
|
bytesToSend = currentRequest->writeLen;
|
|
bytesToReceive = currentRequest->readLen;
|
|
// We may have initiated a stop bit before this without waiting for it.
|
|
// Wait for stop bit to be sent before sending start.
|
|
while (TWCR & (1<<TWSTO)) {}
|
|
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT)|(1<<TWEA)|(1<<TWSTA); // Send Start
|
|
}
|
|
|
|
/***************************************************************************
|
|
* Initiate a stop bit for transmission (does not interrupt)
|
|
***************************************************************************/
|
|
void I2CManagerClass::I2C_sendStop() {
|
|
TWDR = 0xff; // Default condition = SDA released
|
|
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA)|(1<<TWSTO); // Send Stop
|
|
}
|
|
|
|
/***************************************************************************
|
|
* Close I2C down
|
|
***************************************************************************/
|
|
void I2CManagerClass::I2C_close() {
|
|
// disable TWI
|
|
I2C_sendStop();
|
|
while (TWCR & (1<<TWSTO)) {}
|
|
TWCR = (1<<TWINT); // clear any interrupt and stop twi.
|
|
}
|
|
|
|
/***************************************************************************
|
|
* Main state machine for I2C, called from interrupt handler or,
|
|
* if I2C_USE_INTERRUPTS isn't defined, from the I2CManagerClass::loop() function
|
|
* (and therefore, indirectly, from I2CRB::wait() and I2CRB::isBusy()).
|
|
***************************************************************************/
|
|
void I2CManagerClass::I2C_handleInterrupt() {
|
|
if (!(TWCR & (1<<TWINT))) return; // Nothing to do.
|
|
|
|
uint8_t twsr = TWSR & 0xF8;
|
|
|
|
// Cases are ordered so that the most frequently used ones are tested first.
|
|
switch (twsr) {
|
|
case TWI_MTX_DATA_ACK: // Data byte has been transmitted and ACK received
|
|
case TWI_MTX_ADR_ACK: // SLA+W has been transmitted and ACK received
|
|
if (bytesToSend) { // Send first.
|
|
if (operation == OPERATION_SEND_P)
|
|
TWDR = GETFLASH(currentRequest->writeBuffer + (txCount++));
|
|
else
|
|
TWDR = currentRequest->writeBuffer[txCount++];
|
|
bytesToSend--;
|
|
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT)|(1<<TWEA);
|
|
} else if (bytesToReceive) { // All sent, anything to receive?
|
|
while (TWCR & (1<<TWSTO)) {} // Wait for stop to be sent
|
|
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT)|(1<<TWEA)|(1<<TWSTA); // Send Start
|
|
} else { // Nothing left to send or receive
|
|
TWDR = 0xff; // Default condition = SDA released
|
|
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA)|(1<<TWSTO); // Send Stop
|
|
state = I2C_STATUS_OK;
|
|
}
|
|
break;
|
|
case TWI_MRX_DATA_ACK: // Data byte has been received and ACK transmitted
|
|
if (bytesToReceive > 0) {
|
|
currentRequest->readBuffer[rxCount++] = TWDR;
|
|
bytesToReceive--;
|
|
}
|
|
/* fallthrough */
|
|
case TWI_MRX_ADR_ACK: // SLA+R has been sent and ACK received
|
|
if (bytesToReceive <= 1) {
|
|
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT); // Send NACK after next reception
|
|
} else {
|
|
// send ack
|
|
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT)|(1<<TWEA);
|
|
}
|
|
break;
|
|
case TWI_MRX_DATA_NACK: // Data byte has been received and NACK transmitted
|
|
if (bytesToReceive > 0) {
|
|
currentRequest->readBuffer[rxCount++] = TWDR;
|
|
bytesToReceive--;
|
|
}
|
|
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA)|(1<<TWSTO); // Send Stop
|
|
state = I2C_STATUS_OK;
|
|
break;
|
|
case TWI_START: // START has been transmitted
|
|
case TWI_REP_START: // Repeated START has been transmitted
|
|
// Set up address and R/W
|
|
if (operation == OPERATION_READ || (operation==OPERATION_REQUEST && !bytesToSend))
|
|
TWDR = (currentRequest->i2cAddress << 1) | 1; // SLA+R
|
|
else
|
|
TWDR = (currentRequest->i2cAddress << 1) | 0; // SLA+W
|
|
TWCR = (1<<TWEN)|ENABLE_TWI_INTERRUPT|(1<<TWINT)|(1<<TWEA);
|
|
break;
|
|
case TWI_MTX_ADR_NACK: // SLA+W has been transmitted and NACK received
|
|
case TWI_MRX_ADR_NACK: // SLA+R has been transmitted and NACK received
|
|
case TWI_MTX_DATA_NACK: // Data byte has been transmitted and NACK received
|
|
TWDR = 0xff; // Default condition = SDA released
|
|
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA)|(1<<TWSTO); // Send Stop
|
|
state = I2C_STATUS_NEGATIVE_ACKNOWLEDGE;
|
|
break;
|
|
case TWI_ARB_LOST: // Arbitration lost
|
|
// Restart transaction from start.
|
|
I2C_sendStart();
|
|
break;
|
|
case TWI_BUS_ERROR: // Bus error due to an illegal START or STOP condition
|
|
default:
|
|
TWDR = 0xff; // Default condition = SDA released
|
|
TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA)|(1<<TWSTO); // Send Stop
|
|
state = I2C_STATUS_TRANSMIT_ERROR;
|
|
}
|
|
}
|
|
|
|
#if defined(I2C_USE_INTERRUPTS)
|
|
ISR(TWI_vect) {
|
|
I2CManagerClass::handleInterrupt();
|
|
}
|
|
#endif
|
|
|
|
#endif /* I2CMANAGER_AVR_H */
|