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https://github.com/DCC-EX/CommandStation-EX.git
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ba9b363058
Following on from the change to I2CManager_SAMD.h, the capability of deferring a request to change the speed of the I2C has been removed from the SAMD driver and put into the common NonBlocking code, so that all native drivers benefit from it.
249 lines
9.5 KiB
C
249 lines
9.5 KiB
C
/*
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* © 2022 Paul M Antoine
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* © 2023, Neil McKechnie
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* All rights reserved.
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*
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* This file is part of CommandStation-EX
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*
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* This is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* It is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef I2CMANAGER_SAMD_H
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#define I2CMANAGER_SAMD_H
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#include <Arduino.h>
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#include "I2CManager.h"
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//#include <avr/io.h>
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//#include <avr/interrupt.h>
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#include <wiring_private.h>
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// Storage for new baud rate. Zero means no change pending
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static uint32_t pendingBaudRate = 0;
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/***************************************************************************
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* Interrupt handler.
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* IRQ handler for SERCOM3 which is the default I2C definition for Arduino Zero
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* compatible variants such as the Sparkfun SAMD21 Dev Breakout etc.
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* Later we may wish to allow use of an alternate I2C bus, or more than one I2C
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* bus on the SAMD architecture
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***************************************************************************/
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#if defined(I2C_USE_INTERRUPTS) && defined(ARDUINO_SAMD_ZERO)
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void SERCOM3_Handler() {
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I2CManagerClass::handleInterrupt();
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}
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#endif
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// Assume SERCOM3 for now - default I2C bus on Arduino Zero and variants of same
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Sercom *s = SERCOM3;
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/***************************************************************************
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* Set I2C clock speed register. This should only be called outside of
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* a transmission. The I2CManagerClass::_setClock() function ensures
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* that it is only called at the beginning of an I2C transaction.
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***************************************************************************/
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void I2CManagerClass::I2C_setClock(uint32_t i2cClockSpeed) {
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// Calculate a rise time appropriate to the requested bus speed
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int t_rise;
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if (i2cClockSpeed < 200000L) {
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i2cClockSpeed = 100000L;
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t_rise = 1000;
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} else if (i2cClockSpeed < 800000L) {
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i2cClockSpeed = 400000L;
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t_rise = 300;
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} else if (i2cClockSpeed < 1200000L) {
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i2cClockSpeed = 1000000L;
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t_rise = 120;
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} else {
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i2cClockSpeed = 100000L;
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t_rise = 1000;
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}
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// Wait while the bus is busy
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while (s->I2CM.STATUS.bit.BUSSTATE != 0x1);
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// Disable the I2C master mode and wait for sync
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s->I2CM.CTRLA.bit.ENABLE = 0 ;
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while (s->I2CM.SYNCBUSY.bit.ENABLE != 0);
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// Calculate baudrate - using a rise time appropriate for the speed
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s->I2CM.BAUD.bit.BAUD = SystemCoreClock / (2 * i2cClockSpeed) - 5 - (((SystemCoreClock / 1000000) * t_rise) / (2 * 1000));
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// Enable the I2C master mode and wait for sync
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s->I2CM.CTRLA.bit.ENABLE = 1 ;
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while (s->I2CM.SYNCBUSY.bit.ENABLE != 0);
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// Setting bus idle mode and wait for sync
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s->I2CM.STATUS.bit.BUSSTATE = 1 ;
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while (s->I2CM.SYNCBUSY.bit.SYSOP != 0);
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}
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/***************************************************************************
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* Initialise I2C registers.
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***************************************************************************/
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void I2CManagerClass::I2C_init()
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{
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//Setting clock
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GCLK->CLKCTRL.reg = GCLK_CLKCTRL_ID(GCM_SERCOM3_CORE) | // Generic Clock 0 (SERCOM3)
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GCLK_CLKCTRL_GEN_GCLK0 | // Generic Clock Generator 0 is source
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GCLK_CLKCTRL_CLKEN ;
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/* Wait for peripheral clock synchronization */
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while ( GCLK->STATUS.reg & GCLK_STATUS_SYNCBUSY );
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// Software reset the SERCOM
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s->I2CM.CTRLA.bit.SWRST = 1;
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//Wait both bits Software Reset from CTRLA and SYNCBUSY are equal to 0
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while(s->I2CM.CTRLA.bit.SWRST || s->I2CM.SYNCBUSY.bit.SWRST);
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// Set master mode and enable SCL Clock Stretch mode (stretch after ACK bit)
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s->I2CM.CTRLA.reg = SERCOM_I2CM_CTRLA_MODE( I2C_MASTER_OPERATION )/* |
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SERCOM_I2CM_CTRLA_SCLSM*/ ;
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// Enable Smart mode (but not Quick Command)
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s->I2CM.CTRLB.reg = SERCOM_I2CM_CTRLB_SMEN;
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#if defined(I2C_USE_INTERRUPTS)
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// Setting NVIC
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NVIC_EnableIRQ(SERCOM3_IRQn);
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NVIC_SetPriority (SERCOM3_IRQn, SERCOM_NVIC_PRIORITY); // Match default SERCOM priorities
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// NVIC_SetPriority (SERCOM3_IRQn, 0); // Set highest priority
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// Enable all interrupts
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s->I2CM.INTENSET.reg = SERCOM_I2CM_INTENSET_MB | SERCOM_I2CM_INTENSET_SB | SERCOM_I2CM_INTENSET_ERROR;
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#endif
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// Calculate baudrate and set default rate for now
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s->I2CM.BAUD.bit.BAUD = SystemCoreClock / ( 2 * I2C_FREQ) - 7 / (2 * 1000);
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// Enable the I2C master mode and wait for sync
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s->I2CM.CTRLA.bit.ENABLE = 1 ;
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while (s->I2CM.SYNCBUSY.bit.ENABLE != 0);
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// Setting bus idle mode and wait for sync
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s->I2CM.STATUS.bit.BUSSTATE = 1 ;
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while (s->I2CM.SYNCBUSY.bit.SYSOP != 0);
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// Set SDA/SCL pins as outputs and enable pullups, at present we assume these are
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// the default ones for SERCOM3 (see assumption above)
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pinPeripheral(PIN_WIRE_SDA, g_APinDescription[PIN_WIRE_SDA].ulPinType);
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pinPeripheral(PIN_WIRE_SCL, g_APinDescription[PIN_WIRE_SCL].ulPinType);
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// Enable the SCL and SDA pins on the sercom: includes increased driver strength,
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// pull-up resistors and pin multiplexer
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PORT->Group[g_APinDescription[PIN_WIRE_SCL].ulPort].PINCFG[g_APinDescription[PIN_WIRE_SCL].ulPin].reg =
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PORT_PINCFG_DRVSTR | PORT_PINCFG_PULLEN | PORT_PINCFG_PMUXEN;
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PORT->Group[g_APinDescription[PIN_WIRE_SDA].ulPort].PINCFG[g_APinDescription[PIN_WIRE_SDA].ulPin].reg =
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PORT_PINCFG_DRVSTR | PORT_PINCFG_PULLEN | PORT_PINCFG_PMUXEN;
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}
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/***************************************************************************
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* Initiate a start bit for transmission.
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***************************************************************************/
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void I2CManagerClass::I2C_sendStart() {
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// Set counters here in case this is a retry.
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bytesToSend = currentRequest->writeLen;
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bytesToReceive = currentRequest->readLen;
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// On a single-master I2C bus, the start bit won't be sent until the bus
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// state goes to IDLE so we can request it without waiting. On a
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// multi-master bus, the bus may be BUSY under control of another master,
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// in which case we can avoid some arbitration failures by waiting until
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// the bus state is IDLE. We don't do that here.
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// If anything to send, initiate write. Otherwise initiate read.
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if (operation == OPERATION_READ || ((operation == OPERATION_REQUEST) && !bytesToSend))
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{
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// Send start and address with read flag (1) or'd in
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s->I2CM.ADDR.bit.ADDR = (currentRequest->i2cAddress << 1) | 1;
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}
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else {
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// Send start and address with write flag (0) or'd in
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s->I2CM.ADDR.bit.ADDR = (currentRequest->i2cAddress << 1ul) | 0;
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}
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}
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/***************************************************************************
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* Initiate a stop bit for transmission (does not interrupt)
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***************************************************************************/
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void I2CManagerClass::I2C_sendStop() {
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s->I2CM.CTRLB.bit.CMD = 3; // Stop condition
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}
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/***************************************************************************
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* Close I2C down
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***************************************************************************/
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void I2CManagerClass::I2C_close() {
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I2C_sendStop();
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// Disable the I2C master mode and wait for sync
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s->I2CM.CTRLA.bit.ENABLE = 0 ;
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// Wait for up to 500us only.
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unsigned long startTime = micros();
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while (s->I2CM.SYNCBUSY.bit.ENABLE != 0) {
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if (micros() - startTime >= 500UL) break;
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}
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}
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/***************************************************************************
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* Main state machine for I2C, called from interrupt handler or,
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* if I2C_USE_INTERRUPTS isn't defined, from the I2CManagerClass::loop() function
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* (and therefore, indirectly, from I2CRB::wait() and I2CRB::isBusy()).
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***************************************************************************/
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void I2CManagerClass::I2C_handleInterrupt() {
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if (s->I2CM.STATUS.bit.ARBLOST) {
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// Arbitration lost, restart
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I2C_sendStart(); // Reinitiate request
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} else if (s->I2CM.STATUS.bit.BUSERR) {
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// Bus error
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state = I2C_STATUS_BUS_ERROR;
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} else if (s->I2CM.INTFLAG.bit.MB) {
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// Master write completed
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if (s->I2CM.STATUS.bit.RXNACK) {
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// Nacked, send stop.
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I2C_sendStop();
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state = I2C_STATUS_NEGATIVE_ACKNOWLEDGE;
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} else if (bytesToSend) {
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// Acked, so send next byte
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s->I2CM.DATA.bit.DATA = currentRequest->writeBuffer[txCount++];
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bytesToSend--;
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} else if (bytesToReceive) {
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// Last sent byte acked and no more to send. Send repeated start, address and read bit.
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s->I2CM.ADDR.bit.ADDR = (currentRequest->i2cAddress << 1) | 1;
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} else {
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// No more data to send/receive. Initiate a STOP condition.
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I2C_sendStop();
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state = I2C_STATUS_OK; // Done
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}
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} else if (s->I2CM.INTFLAG.bit.SB) {
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// Master read completed without errors
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if (bytesToReceive == 1) {
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s->I2CM.CTRLB.bit.ACKACT = 1; // NAK final byte
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I2C_sendStop(); // send stop
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currentRequest->readBuffer[rxCount++] = s->I2CM.DATA.bit.DATA; // Store received byte
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bytesToReceive = 0;
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state = I2C_STATUS_OK; // done
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} else if (bytesToReceive) {
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s->I2CM.CTRLB.bit.ACKACT = 0; // ACK all but final byte
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currentRequest->readBuffer[rxCount++] = s->I2CM.DATA.bit.DATA; // Store received byte
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bytesToReceive--;
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}
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}
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}
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#endif /* I2CMANAGER_SAMD_H */
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