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CommandStation-EX/I2CManager_STM32.h

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/*
* © 2022-23 Paul M Antoine
* © 2023, 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_STM32_H
#define I2CMANAGER_STM32_H
#include <Arduino.h>
#include "I2CManager.h"
#include "I2CManager_NonBlocking.h" // to satisfy intellisense
//#include <avr/io.h>
//#include <avr/interrupt.h>
#include <wiring_private.h>
/***************************************************************************
* Interrupt handler.
* IRQ handler for SERCOM3 which is the default I2C definition for Arduino Zero
* compatible variants such as the Sparkfun SAMD21 Dev Breakout etc.
* Later we may wish to allow use of an alternate I2C bus, or more than one I2C
* bus on the SAMD architecture
***************************************************************************/
#if defined(I2C_USE_INTERRUPTS) && defined(ARDUINO_ARCH_STM32)
void I2C1_IRQHandler() {
I2CManager.handleInterrupt();
}
#endif
// Assume I2C1 for now - default I2C bus on Nucleo-F411RE and likely Nucleo-64 variants
I2C_TypeDef *s = I2C1;
#define I2C_IRQn I2C1_EV_IRQn
#define I2C_BUSFREQ 16
// I2C SR1 Status Register #1 bit definitions for convenience
// #define I2C_SR1_SMBALERT (1<<15) // SMBus alert
// #define I2C_SR1_TIMEOUT (1<<14) // Timeout of Tlow error
// #define I2C_SR1_PECERR (1<<12) // PEC error in reception
// #define I2C_SR1_OVR (1<<11) // Overrun/Underrun error
// #define I2C_SR1_AF (1<<10) // Acknowledge failure
// #define I2C_SR1_ARLO (1<<9) // Arbitration lost (master mode)
// #define I2C_SR1_BERR (1<<8) // Bus error (misplaced start or stop condition)
// #define I2C_SR1_TxE (1<<7) // Data register empty on transmit
// #define I2C_SR1_RxNE (1<<6) // Data register not empty on receive
// #define I2C_SR1_STOPF (1<<4) // Stop detection (slave mode)
// #define I2C_SR1_ADD10 (1<<3) // 10 bit header sent
// #define I2C_SR1_BTF (1<<2) // Byte transfer finished - data transfer done
// #define I2C_SR1_ADDR (1<<1) // Address sent (master) or matched (slave)
// #define I2C_SR1_SB (1<<0) // Start bit (master mode) 1=start condition generated
// I2C CR1 Control Register #1 bit definitions for convenience
// #define I2C_CR1_SWRST (1<<15) // Software reset - places peripheral under reset
// #define I2C_CR1_ALERT (1<<13) // SMBus alert assertion
// #define I2C_CR1_PEC (1<<12) // Packet Error Checking transfer in progress
// #define I2C_CR1_POS (1<<11) // Acknowledge/PEC Postion (for data reception in PEC mode)
// #define I2C_CR1_ACK (1<<10) // Acknowledge enable - ACK returned after byte is received (address or data)
// #define I2C_CR1_STOP (1<<9) // STOP generated
// #define I2C_CR1_START (1<<8) // START generated
// #define I2C_CR1_NOSTRETCH (1<<7) // Clock stretching disable (slave mode)
// #define I2C_CR1_ENGC (1<<6) // General call (broadcast) enable (address 00h is ACKed)
// #define I2C_CR1_ENPEC (1<<5) // PEC Enable
// #define I2C_CR1_ENARP (1<<4) // ARP enable (SMBus)
// #define I2C_CR1_SMBTYPE (1<<3) // SMBus type, 1=host, 0=device
// #define I2C_CR1_SMBUS (1<<1) // SMBus mode, 1=SMBus, 0=I2C
// #define I2C_CR1_PE (1<<0) // I2C Peripheral enable
/***************************************************************************
* Set I2C clock speed register. This should only be called outside of
* a transmission. The I2CManagerClass::_setClock() function ensures
* that it is only called at the beginning of an I2C transaction.
***************************************************************************/
void I2CManagerClass::I2C_setClock(uint32_t i2cClockSpeed) {
// Calculate a rise time appropriate to the requested bus speed
// Use 10x the rise time spec to enable integer divide of 62.5ns clock period
uint16_t t_rise;
uint32_t ccr_freq;
if (i2cClockSpeed < 200000L) {
// i2cClockSpeed = 100000L;
t_rise = 0x11; // (1000ns /62.5ns) + 1;
}
else if (i2cClockSpeed < 800000L)
{
i2cClockSpeed = 400000L;
t_rise = 0x06; // (300ns / 62.5ns) + 1;
// } else if (i2cClockSpeed < 1200000L) {
// i2cClockSpeed = 1000000L;
// t_rise = 120;
}
else
{
i2cClockSpeed = 100000L;
t_rise = 0x11; // (1000ns /62.5ns) + 1;
}
// Enable the I2C master mode
s->CR1 &= ~(I2C_CR1_PE); // Enable I2C
// Software reset the I2C peripheral
// s->CR1 |= I2C_CR1_SWRST; // reset the I2C
// Release reset
// s->CR1 &= ~(I2C_CR1_SWRST); // Normal operation
// Calculate baudrate - using a rise time appropriate for the speed
ccr_freq = I2C_BUSFREQ * 1000000 / i2cClockSpeed / 2;
// Bit 15: I2C Master mode, 0=standard, 1=Fast Mode
// Bit 14: Duty, fast mode duty cycle
// Bit 11-0: FREQR = 16MHz => TPCLK1 = 62.5ns, so CCR divisor must be 0x50 (80 * 62.5ns = 5000ns)
s->CCR = (uint16_t)ccr_freq;
// Configure the rise time register
s->TRISE = t_rise; // 1000 ns / 62.5 ns = 16 + 1
// Enable the I2C master mode
s->CR1 |= I2C_CR1_PE; // Enable I2C
}
/***************************************************************************
* Initialise I2C registers.
***************************************************************************/
void I2CManagerClass::I2C_init()
{
//Setting up the clocks
RCC->APB1ENR |= (1<<21); // Enable I2C CLOCK
RCC->AHB1ENR |= (1<<1); // Enable GPIOB CLOCK for PB8/PB9
// Standard I2C pins are SCL on PB8 and SDA on PB9
// Bits (17:16)= 1:0 --> Alternate Function for Pin PB8;
// Bits (19:18)= 1:0 --> Alternate Function for Pin PB9
GPIOB->MODER |= (2<<(8*2)) | (2<<(9*2)); // PB8 and PB9 set to ALT function
GPIOB->OTYPER |= (1<<8) | (1<<9); // PB8 and PB9 set to open drain output capability
GPIOB->OSPEEDR |= (3<<(8*2)) | (3<<(9*2)); // PB8 and PB9 set to High Speed mode
GPIOB->PUPDR |= (1<<(8*2)) | (1<<(9*2)); // PB8 and PB9 set to pull-up capability
// Alt Function High register routing pins PB8 and PB9 for I2C1:
// Bits (3:2:1:0) = 0:1:0:0 --> AF4 for pin PB8
// Bits (7:6:5:4) = 0:1:0:0 --> AF4 for pin PB9
GPIOB->AFR[1] |= (4<<0) | (4<<4); // PB8 on low nibble, PB9 on next nibble up
// Software reset the I2C peripheral
s->CR1 |= I2C_CR1_SWRST; // reset the I2C
s->CR1 &= ~(I2C_CR1_SWRST); // Normal operation
// Program the peripheral input clock in CR2 Register in order to generate correct timings
s->CR2 |= I2C_BUSFREQ; // PCLK1 FREQUENCY in MHz
#if defined(I2C_USE_INTERRUPTS)
// Setting NVIC
NVIC_SetPriority(I2C_IRQn, 1); // Match default priorities
NVIC_EnableIRQ(I2C_IRQn);
// CR2 Interrupt Settings
// Bit 15-13: reserved
// Bit 12: LAST - DMA last transfer
// Bit 11: DMAEN - DMA enable
// Bit 10: ITBUFEN - Buffer interrupt enable
// Bit 9: ITEVTEN - Event interrupt enable
// Bit 8: ITERREN - Error interrupt enable
// Bit 7-6: reserved
// Bit 5-0: FREQ - Peripheral clock frequency (max 50MHz)
// s->CR2 |= 0x0700; // Enable Buffer, Event and Error interrupts
s->CR2 |= 0x0300; // Enable Event and Error interrupts
#endif
// Calculate baudrate and set default rate for now
// Configure the Clock Control Register for 100KHz SCL frequency
// Bit 15: I2C Master mode, 0=standard, 1=Fast Mode
// Bit 14: Duty, fast mode duty cycle
// Bit 11-0: FREQR = 16MHz => TPCLK1 = 62.5ns, so CCR divisor must be 0x50 (80 * 62.5ns = 5000ns)
s->CCR = 0x0050;
// Configure the rise time register - max allowed in 1000ns
s->TRISE = 0x0011; // 1000 ns / 62.5 ns = 16 + 1
// Enable the I2C master mode
s->CR1 |= I2C_CR1_PE; // Enable I2C
// Setting bus idle mode and wait for sync
}
/***************************************************************************
* Initiate a start bit for transmission.
***************************************************************************/
void I2CManagerClass::I2C_sendStart() {
// Set counters here in case this is a retry.
rxCount = txCount = 0;
uint8_t temp;
// On a single-master I2C bus, the start bit won't be sent until the bus
// state goes to IDLE so we can request it without waiting. On a
// multi-master bus, the bus may be BUSY under control of another master,
// in which case we can avoid some arbitration failures by waiting until
// the bus state is IDLE. We don't do that here.
// If anything to send, initiate write. Otherwise initiate read.
if (operation == OPERATION_READ || ((operation == OPERATION_REQUEST) && !bytesToSend))
{
// Send start for read operation
s->CR1 |= I2C_CR1_ACK; // Enable the ACK
s->CR1 |= I2C_CR1_START; // Generate START
// Send address with read flag (1) or'd in
s->DR = (deviceAddress << 1) | 1; // send the address
while (!(s->SR1 && I2C_SR1_ADDR)); // wait for ADDR bit to set
// Special case for 1 byte reads!
if (bytesToReceive == 1)
{
s->CR1 &= ~I2C_CR1_ACK; // clear the ACK bit
temp = I2C1->SR1 | I2C1->SR2; // read SR1 and SR2 to clear the ADDR bit.... EV6 condition
s->CR1 |= I2C_CR1_STOP; // Stop I2C
}
else
temp = s->SR1 | s->SR2; // read SR1 and SR2 to clear the ADDR bit
}
else {
// Send start for write operation
s->CR1 |= I2C_CR1_ACK; // Enable the ACK
s->CR1 |= I2C_CR1_START; // Generate START
// Send address with write flag (0) or'd in
s->DR = (deviceAddress << 1) | 0; // send the address
while (!(s->SR1 && I2C_SR1_ADDR)); // wait for ADDR bit to set
temp = s->SR1 | s->SR2; // read SR1 and SR2 to clear the ADDR bit
}
}
/***************************************************************************
* Initiate a stop bit for transmission (does not interrupt)
***************************************************************************/
void I2CManagerClass::I2C_sendStop() {
s->CR1 |= I2C_CR1_STOP; // Stop I2C
}
/***************************************************************************
* Close I2C down
***************************************************************************/
void I2CManagerClass::I2C_close() {
I2C_sendStop();
// Disable the I2C master mode and wait for sync
s->CR1 &= ~I2C_CR1_PE; // Disable I2C peripheral
// Should never happen, but wait for up to 500us only.
unsigned long startTime = micros();
while ((s->CR1 && I2C_CR1_PE) != 0) {
if (micros() - startTime >= 500UL) break;
}
}
/***************************************************************************
* 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 (s->SR1 && I2C_SR1_ARLO) {
// Arbitration lost, restart
I2C_sendStart(); // Reinitiate request
} else if (s->SR1 && I2C_SR1_BERR) {
// Bus error
completionStatus = I2C_STATUS_BUS_ERROR;
state = I2C_STATE_COMPLETED;
} else if (s->SR1 && I2C_SR1_TXE) {
// Master write completed
if (s->SR1 && (1<<10)) {
// Nacked, send stop.
I2C_sendStop();
completionStatus = I2C_STATUS_NEGATIVE_ACKNOWLEDGE;
state = I2C_STATE_COMPLETED;
} else if (bytesToSend) {
// Acked, so send next byte
s->DR = sendBuffer[txCount++];
bytesToSend--;
} else if (bytesToReceive) {
// Last sent byte acked and no more to send. Send repeated start, address and read bit.
// s->I2CM.ADDR.bit.ADDR = (deviceAddress << 1) | 1;
} else {
// Check both TxE/BTF == 1 before generating stop
while (!(s->SR1 && I2C_SR1_TXE)); // Check TxE
while (!(s->SR1 && I2C_SR1_BTF)); // Check BTF
// No more data to send/receive. Initiate a STOP condition and finish
I2C_sendStop();
state = I2C_STATE_COMPLETED;
}
} else if (s->SR1 && I2C_SR1_RXNE) {
// Master read completed without errors
if (bytesToReceive == 1) {
// s->I2CM.CTRLB.bit.ACKACT = 1; // NAK final byte
I2C_sendStop(); // send stop
receiveBuffer[rxCount++] = s->DR; // Store received byte
bytesToReceive = 0;
state = I2C_STATE_COMPLETED;
} else if (bytesToReceive) {
// s->I2CM.CTRLB.bit.ACKACT = 0; // ACK all but final byte
receiveBuffer[rxCount++] = s->DR; // Store received byte
bytesToReceive--;
}
}
}
#endif /* I2CMANAGER_STM32_H */
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