/*
* © 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 .
*/
#ifndef I2CMANAGER_STM32_H
#define I2CMANAGER_STM32_H
#include
#include "I2CManager.h"
#include "I2CManager_NonBlocking.h" // to satisfy intellisense
#include
#include "stm32f4xx_hal_rcc.h"
/*****************************************************************************
* STM32F4xx I2C native driver support
*
* Nucleo-64 and Nucleo-144 boards all use I2C1 as the default I2C peripheral
* Later we may wish to support other STM32 boards, allow use of an alternate
* I2C bus, or more than one I2C bus on the STM32 architecture
*****************************************************************************/
#if defined(I2C_USE_INTERRUPTS) && defined(ARDUINO_ARCH_STM32)
#if defined(ARDUINO_NUCLEO_F401RE) || defined(ARDUINO_NUCLEO_F411RE) || defined(ARDUINO_NUCLEO_F446RE) \
|| defined(ARDUINO_NUCLEO_F412ZG) || defined(ARDUINO_NUCLEO_F413ZH) \
|| defined(ARDUINO_NUCLEO_F429ZI) || defined(ARDUINO_NUCLEO_F446ZE)
// Assume I2C1 for now - default I2C bus on Nucleo-F411RE and likely all Nucleo-64
// and Nucleo-144 variants
I2C_TypeDef *s = I2C1;
// In init we will ask the STM32 HAL layer for the configured APB1 clock frequency in Hz
uint32_t APB1clk1; // Peripheral Input Clock speed in Hz.
uint32_t i2c_MHz; // Peripheral Input Clock speed in MHz.
// IRQ handler for I2C1, replacing the weak definition in the STM32 HAL
extern "C" void I2C1_EV_IRQHandler(void) {
I2CManager.handleInterrupt();
}
extern "C" void I2C1_ER_IRQHandler(void) {
I2CManager.handleInterrupt();
}
#else
#warning STM32 board selected is not yet supported - so I2C1 peripheral is not defined
#endif
#endif
// Peripheral Input Clock speed in MHz.
// For STM32F446RE, the speed is 45MHz. Ideally, this should be determined
// at run-time from the APB1 clock, as it can vary from STM32 family to family.
// #define I2C_PERIPH_CLK 45
// 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
// States of the STM32 I2C driver state machine
enum {TS_IDLE,TS_START,TS_W_ADDR,TS_W_DATA,TS_W_STOP,TS_R_ADDR,TS_R_DATA,TS_R_STOP};
/***************************************************************************
* 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 50ns clock period
uint16_t t_rise;
while (s->CR1 & I2C_CR1_STOP); // Prevents lockup by guarding further
// writes to CR1 while STOP is being executed!
// Disable the I2C device, as TRISE can only be programmed whilst disabled
s->CR1 &= ~(I2C_CR1_PE); // Disable I2C
s->CR1 |= I2C_CR1_SWRST; // reset the I2C
asm("nop"); // wait a bit... suggestion from online!
s->CR1 &= ~(I2C_CR1_SWRST); // Normal operation
if (i2cClockSpeed > 100000UL)
{
// if (i2cClockSpeed > 400000L)
// i2cClockSpeed = 400000L;
t_rise = 300; // nanoseconds
}
else
{
// i2cClockSpeed = 100000L;
t_rise = 1000; // nanoseconds
}
// Configure the rise time register - max allowed tRISE is 1000ns,
// so value = 1000ns * I2C_PERIPH_CLK MHz / 1000 + 1.
s->TRISE = (t_rise * i2c_MHz / 1000) + 1;
// Bit 15: I2C Master mode, 0=standard, 1=Fast Mode
// Bit 14: Duty, fast mode duty cycle (use 2:1)
// Bit 11-0: FREQR
// if (i2cClockSpeed > 400000UL) {
// // In fast mode plus, I2C period is 3 * CCR * TPCLK1.
// // s->CCR &= ~(0x3000); // Clear all bits except 12 and 13 which must remain per reset value
// s->CCR = APB1clk1 / 3 / i2cClockSpeed; // Set I2C clockspeed to start!
// s->CCR |= 0xC000; // We need Fast Mode AND DUTY bits set
// } else {
// In standard and fast mode, I2C period is 2 * CCR * TPCLK1
s->CCR &= ~(0x3000); // Clear all bits except 12 and 13 which must remain per reset value
s->CCR |= (APB1clk1 / 2 / i2cClockSpeed); // Set I2C clockspeed to start!
// s->CCR |= (i2c_MHz * 500 / (i2cClockSpeed / 1000)); // Set I2C clockspeed to start!
// if (i2cClockSpeed > 100000UL)
// s->CCR |= 0xC000; // We need Fast Mode bits set as well
// }
// DIAG(F("I2C_init() peripheral clock is now: %d, full reg is %x"), (s->CR2 & 0xFF), s->CR2);
// DIAG(F("I2C_init() peripheral CCR is now: %d"), s->CCR);
// DIAG(F("I2C_init() peripheral TRISE is now: %d"), s->TRISE);
// Enable the I2C master mode
s->CR1 |= I2C_CR1_PE; // Enable I2C
}
/***************************************************************************
* Initialise I2C registers.
***************************************************************************/
void I2CManagerClass::I2C_init()
{
// Query the clockspeed from the STM32 HAL layer
APB1clk1 = HAL_RCC_GetPCLK1Freq();
i2c_MHz = APB1clk1 / 1000000UL;
// DIAG(F("I2C_init() peripheral clock speed is: %d"), i2c_MHz);
// Enable clocks
RCC->APB1ENR |= RCC_APB1ENR_I2C1EN;//(1 << 21); // Enable I2C CLOCK
// Reset the I2C1 peripheral to initial state
RCC->APB1RSTR |= RCC_APB1RSTR_I2C1RST;
RCC->APB1RSTR &= ~RCC_APB1RSTR_I2C1RST;
// Standard I2C pins are SCL on PB8 and SDA on PB9
RCC->AHB1ENR |= (1<<1); // Enable GPIOB CLOCK for PB8/PB9
// Bits (17:16)= 1:0 --> Alternate Function for Pin PB8;
// Bits (19:18)= 1:0 --> Alternate Function for Pin PB9
GPIOB->MODER &= ~((3<<(8*2)) | (3<<(9*2))); // Clear all MODER bits for PB8 and 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 &= ~((3<<(8*2)) | (3<<(9*2))); // Clear all PUPDR bits for PB8 and PB9
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] &= ~((15<<0) | (15<<4)); // Clear all AFR bits for PB8 on low nibble, PB9 on next nibble up
GPIOB->AFR[1] |= (4<<0) | (4<<4); // PB8 on low nibble, PB9 on next nibble up
// Software reset the I2C peripheral
I2C1->CR1 &= ~I2C_CR1_PE; // Disable I2C1 peripheral
s->CR1 |= I2C_CR1_SWRST; // reset the I2C
asm("nop"); // wait a bit... suggestion from online!
s->CR1 &= ~(I2C_CR1_SWRST); // Normal operation
// Clear all bits in I2C CR2 register except reserved bits
s->CR2 &= 0xE000;
// Set I2C peripheral clock frequency
// s->CR2 |= I2C_PERIPH_CLK;
s->CR2 |= i2c_MHz;
// DIAG(F("I2C_init() peripheral clock is now: %d"), s->CR2);
// set own address to 00 - not used in master mode
I2C1->OAR1 = (1 << 14); // bit 14 should be kept at 1 according to the datasheet
#if defined(I2C_USE_INTERRUPTS)
// Setting NVIC
NVIC_SetPriority(I2C1_EV_IRQn, 1); // Match default priorities
NVIC_EnableIRQ(I2C1_EV_IRQn);
NVIC_SetPriority(I2C1_ER_IRQn, 1); // Match default priorities
NVIC_EnableIRQ(I2C1_ER_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 |= (I2C_CR2_ITBUFEN | I2C_CR2_ITEVTEN | I2C_CR2_ITERREN); // Enable Buffer, Event and Error interrupts
#endif
// DIAG(F("I2C_init() setting initial I2C clock to 100KHz"));
// 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: so CCR divisor would be clk / 2 / 100000 (where clk is in Hz)
// s->CCR = I2C_PERIPH_CLK * 5;
s->CCR &= ~(0x3000); // Clear all bits except 12 and 13 which must remain per reset value
s->CCR |= (APB1clk1 / 2 / 100000UL); // Set a default of 100KHz I2C clockspeed to start!
// Configure the rise time register - max allowed is 1000ns, so value = 1000ns * I2C_PERIPH_CLK MHz / 1000 + 1.
s->TRISE = (1000 * i2c_MHz / 1000) + 1;
// DIAG(F("I2C_init() peripheral clock is now: %d, full reg is %x"), (s->CR2 & 0xFF), s->CR2);
// DIAG(F("I2C_init() peripheral CCR is now: %d"), s->CCR);
// DIAG(F("I2C_init() peripheral TRISE is now: %d"), s->TRISE);
// Enable the I2C master mode
s->CR1 |= I2C_CR1_PE; // Enable I2C
}
/***************************************************************************
* Initiate a start bit for transmission.
***************************************************************************/
void I2CManagerClass::I2C_sendStart() {
// Set counters here in case this is a retry.
rxCount = txCount = 0;
// 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.
//while (s->SR2 & I2C_SR2_BUSY) {}
// Check there's no STOP still in progress. If we OR the START bit into CR1
// and the STOP bit is already set, we could output multiple STOP conditions.
while (s->CR1 & I2C_CR1_STOP) {} // Wait for STOP bit to reset
s->CR2 |= (I2C_CR2_ITEVTEN | I2C_CR2_ITERREN); // Enable interrupts
s->CR2 &= ~I2C_CR2_ITBUFEN; // Don't enable buffer interupts yet.
s->CR1 &= ~I2C_CR1_POS; // Clear the POS bit
s->CR1 |= (I2C_CR1_ACK | I2C_CR1_START); // Enable the ACK and generate START
transactionState = TS_START;
}
/***************************************************************************
* 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 ((int32_t)(micros() - startTime) >= 500) break;
}
NVIC_DisableIRQ(I2C1_EV_IRQn);
NVIC_DisableIRQ(I2C1_ER_IRQn);
}
/***************************************************************************
* 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() {
volatile uint16_t temp_sr1, temp_sr2;
temp_sr1 = s->SR1;
// Check for errors first
if (temp_sr1 & (I2C_SR1_AF | I2C_SR1_ARLO | I2C_SR1_BERR)) {
// Check which error flag is set
if (temp_sr1 & I2C_SR1_AF)
{
s->SR1 &= ~(I2C_SR1_AF); // Clear AF
I2C_sendStop(); // Clear the bus
transactionState = TS_IDLE;
completionStatus = I2C_STATUS_NEGATIVE_ACKNOWLEDGE;
state = I2C_STATE_COMPLETED;
}
else if (temp_sr1 & I2C_SR1_ARLO)
{
// Arbitration lost, restart
s->SR1 &= ~(I2C_SR1_ARLO); // Clear ARLO
I2C_sendStart(); // Reinitiate request
transactionState = TS_START;
}
else if (temp_sr1 & I2C_SR1_BERR)
{
// Bus error
s->SR1 &= ~(I2C_SR1_BERR); // Clear BERR
I2C_sendStop(); // Clear the bus
transactionState = TS_IDLE;
completionStatus = I2C_STATUS_BUS_ERROR;
state = I2C_STATE_COMPLETED;
}
}
else {
// No error flags, so process event according to current state.
switch (transactionState) {
case TS_START:
if (temp_sr1 & I2C_SR1_SB) {
// Event EV5
// Start bit has been sent successfully and we have the bus.
// If anything to send, initiate write. Otherwise initiate read.
if (operation == OPERATION_READ || ((operation == OPERATION_REQUEST) && !bytesToSend)) {
// Send address with read flag (1) or'd in
s->DR = (deviceAddress << 1) | 1; // send the address
transactionState = TS_R_ADDR;
} else {
// Send address with write flag (0) or'd in
s->DR = (deviceAddress << 1) | 0; // send the address
transactionState = TS_W_ADDR;
}
}
// SB bit is cleared by writing to DR (already done).
break;
case TS_W_ADDR:
if (temp_sr1 & I2C_SR1_ADDR) {
temp_sr2 = s->SR2; // read SR2 to complete clearing the ADDR bit
// Event EV6
// Address sent successfully, device has ack'd in response.
if (!bytesToSend) {
I2C_sendStop();
transactionState = TS_IDLE;
completionStatus = I2C_STATUS_OK;
state = I2C_STATE_COMPLETED;
} else {
// Put one byte into DR to load shift register.
s->DR = sendBuffer[txCount++];
bytesToSend--;
if (bytesToSend) {
// Put another byte to load DR
s->DR = sendBuffer[txCount++];
bytesToSend--;
}
if (!bytesToSend) {
// No more bytes to send.
// The TXE interrupt occurs when the DR is empty, and the BTF interrupt
// occurs when the shift register is also empty (one character later).
// To avoid repeated TXE interrupts during this time, we disable TXE interrupt.
s->CR2 &= ~I2C_CR2_ITBUFEN; // Wait for BTF interrupt, disable TXE interrupt
transactionState = TS_W_STOP;
} else {
// More data remaining to send after this interrupt, enable TXE interrupt.
s->CR2 |= I2C_CR2_ITBUFEN;
transactionState = TS_W_DATA;
}
}
}
break;
case TS_W_DATA:
if (temp_sr1 & I2C_SR1_TXE) {
// Event EV8_1/EV8
// Transmitter empty, write a byte to it.
if (bytesToSend) {
s->DR = sendBuffer[txCount++];
bytesToSend--;
if (!bytesToSend) {
s->CR2 &= ~I2C_CR2_ITBUFEN; // Disable TXE interrupt
transactionState = TS_W_STOP;
}
}
}
break;
case TS_W_STOP:
if (temp_sr1 & I2C_SR1_BTF) {
// Event EV8_2
// Done, last character sent. Anything to receive?
if (bytesToReceive) {
I2C_sendStart();
// NOTE: Three redundant BTF interrupts take place between the
// first BTF interrupt and the START interrupt. I've tried all sorts
// of ways to eliminate them, and the only thing that worked for
// me was to loop until the BTF bit becomes reset. Either way,
// it's a waste of processor time. Anyone got a solution?
//while (s->SR1 && I2C_SR1_BTF) {}
transactionState = TS_START;
} else {
I2C_sendStop();
transactionState = TS_IDLE;
completionStatus = I2C_STATUS_OK;
state = I2C_STATE_COMPLETED;
}
s->SR1 &= I2C_SR1_BTF; // Clear BTF interrupt
}
break;
case TS_R_ADDR:
if (temp_sr1 & I2C_SR1_ADDR) {
// Event EV6
// Address sent for receive.
// The next bit is different depending on whether there are
// 1 byte, 2 bytes or >2 bytes to be received, in accordance with the
// Programmers Reference RM0390.
if (bytesToReceive == 1) {
// Receive 1 byte
s->CR1 &= ~I2C_CR1_ACK; // Disable ack
temp_sr2 = s->SR2; // read SR2 to complete clearing the ADDR bit
// Next step will occur after a RXNE interrupt, so enable it
s->CR2 |= I2C_CR2_ITBUFEN;
transactionState = TS_R_STOP;
} else if (bytesToReceive == 2) {
// Receive 2 bytes
s->CR1 &= ~I2C_CR1_ACK; // Disable ACK for final byte
s->CR1 |= I2C_CR1_POS; // set POS flag to delay effect of ACK flag
// Next step will occur after a BTF interrupt, so disable RXNE interrupt
s->CR2 &= ~I2C_CR2_ITBUFEN;
temp_sr2 = s->SR2; // read SR2 to complete clearing the ADDR bit
transactionState = TS_R_STOP;
} else {
// >2 bytes, just wait for bytes to come in and ack them for the time being
// (ack flag has already been set).
// Next step will occur after a BTF interrupt, so disable RXNE interrupt
s->CR2 &= ~I2C_CR2_ITBUFEN;
temp_sr2 = s->SR2; // read SR2 to complete clearing the ADDR bit
transactionState = TS_R_DATA;
}
}
break;
case TS_R_DATA:
// Event EV7/EV7_1
if (temp_sr1 & I2C_SR1_BTF) {
// Byte received in receiver - read next byte
if (bytesToReceive == 3) {
// Getting close to the last byte, so a specific sequence is recommended.
s->CR1 &= ~I2C_CR1_ACK; // Reset ack for next byte received.
transactionState = TS_R_STOP;
}
receiveBuffer[rxCount++] = s->DR; // Store received byte
bytesToReceive--;
}
break;
case TS_R_STOP:
if (temp_sr1 & I2C_SR1_BTF) {
// Event EV7 (last one)
// When we've got here, the receiver has got the last two bytes
// (or one byte, if only one byte is being received),
// and NAK has already been sent, so we need to read from the receiver.
if (bytesToReceive) {
if (bytesToReceive > 1)
I2C_sendStop();
while(bytesToReceive) {
receiveBuffer[rxCount++] = s->DR; // Store received byte(s)
bytesToReceive--;
}
// Finish.
transactionState = TS_IDLE;
completionStatus = I2C_STATUS_OK;
state = I2C_STATE_COMPLETED;
}
} else if (temp_sr1 & I2C_SR1_RXNE) {
if (bytesToReceive == 1) {
// One byte on a single-byte transfer. Ack has already been set.
I2C_sendStop();
receiveBuffer[rxCount++] = s->DR; // Store received byte
bytesToReceive--;
// Finish.
transactionState = TS_IDLE;
completionStatus = I2C_STATUS_OK;
state = I2C_STATE_COMPLETED;
} else
s->SR1 &= I2C_SR1_RXNE; // Acknowledge interrupt
}
break;
}
// If we've received an interrupt at any other time, we're not interested so clear it
// to prevent it recurring ad infinitum.
s->SR1 = 0;
}
}
#endif /* I2CMANAGER_STM32_H */