/******************************************************************************
* The MIT License
*
* Copyright (c) 2010 Perry Hung.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy,
* modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*****************************************************************************/
/**
* @file i2c.c
* @brief Inter-Integrated Circuit (I2C) support.
*
* Currently, only master mode is supported.
*/
#include <libmaple/libmaple.h>
#include <libmaple/rcc.h>
#include <libmaple/gpio.h>
#include <libmaple/nvic.h>
#include <libmaple/i2c.h>
#include <libmaple/systick.h>
#include <string.h>
static i2c_dev i2c_dev1 = {
.regs = I2C1_BASE,
.gpio_port = &gpiob,
.sda_pin = 7,
.scl_pin = 6,
.clk_id = RCC_I2C1,
.ev_nvic_line = NVIC_I2C1_EV,
.er_nvic_line = NVIC_I2C1_ER,
.state = I2C_STATE_DISABLED
};
/** I2C1 device */
i2c_dev* const I2C1 = &i2c_dev1;
static i2c_dev i2c_dev2 = {
.regs = I2C2_BASE,
.gpio_port = &gpiob,
.sda_pin = 11,
.scl_pin = 10,
.clk_id = RCC_I2C2,
.ev_nvic_line = NVIC_I2C2_EV,
.er_nvic_line = NVIC_I2C2_ER,
.state = I2C_STATE_DISABLED
};
/** I2C2 device */
i2c_dev* const I2C2 = &i2c_dev2;
static inline int32 wait_for_state_change(i2c_dev *dev,
i2c_state state,
uint32 timeout);
/**
* @brief Fill data register with slave address
* @param dev I2C device
* @param addr Slave address
* @param rw Read/write bit
*/
static inline void i2c_send_slave_addr(i2c_dev *dev, uint32 addr, uint32 rw) {
dev->regs->DR = (addr << 1) | rw;
}
/*
* Simple debugging trail. Define I2C_DEBUG to turn on.
*/
#ifdef I2C_DEBUG
#define NR_CRUMBS 128
static struct crumb crumbs[NR_CRUMBS];
static uint32 cur_crumb = 0;
static inline void i2c_drop_crumb(uint32 event, uint32 arg0, uint32 arg1) {
if (cur_crumb < NR_CRUMBS) {
struct crumb *crumb = &crumbs[cur_crumb++];
crumb->event = event;
crumb->arg0 = arg0;
crumb->arg1 = arg1;
}
}
#define I2C_CRUMB(event, arg0, arg1) i2c_drop_crumb(event, arg0, arg1)
#else
#define I2C_CRUMB(event, arg0, arg1)
#endif
struct crumb {
uint32 event;
uint32 arg0;
uint32 arg1;
};
enum {
IRQ_ENTRY = 1,
TXE_ONLY = 2,
TXE_BTF = 3,
STOP_SENT = 4,
TEST = 5,
RX_ADDR_START = 6,
RX_ADDR_STOP = 7,
RXNE_ONLY = 8,
RXNE_SENDING = 9,
RXNE_START_SENT = 10,
RXNE_STOP_SENT = 11,
RXNE_DONE = 12,
ERROR_ENTRY = 13,
};
/**
* @brief IRQ handler for I2C master. Handles transmission/reception.
* @param dev I2C device
*/
static void i2c_irq_handler(i2c_dev *dev) {
i2c_msg *msg = dev->msg;
uint8 read = msg->flags & I2C_MSG_READ;
uint32 sr1 = dev->regs->SR1;
uint32 sr2 = dev->regs->SR2;
I2C_CRUMB(IRQ_ENTRY, sr1, sr2);
/*
* Reset timeout counter
*/
dev->timestamp = systick_uptime();
/*
* EV5: Start condition sent
*/
if (sr1 & I2C_SR1_SB) {
msg->xferred = 0;
i2c_enable_irq(dev, I2C_IRQ_BUFFER);
/*
* Master receiver
*/
if (read) {
i2c_enable_ack(dev);
}
i2c_send_slave_addr(dev, msg->addr, read);
sr1 = sr2 = 0;
}
/*
* EV6: Slave address sent
*/
if (sr1 & I2C_SR1_ADDR) {
/*
* Special case event EV6_1 for master receiver.
* Generate NACK and restart/stop condition after ADDR
* is cleared.
*/
if (read) {
if (msg->length == 1) {
i2c_disable_ack(dev);
if (dev->msgs_left > 1) {
i2c_start_condition(dev);
I2C_CRUMB(RX_ADDR_START, 0, 0);
} else {
i2c_stop_condition(dev);
I2C_CRUMB(RX_ADDR_STOP, 0, 0);
}
}
} else {
/*
* Master transmitter: write first byte to fill shift
* register. We should get another TXE interrupt
* immediately to fill DR again.
*/
if (msg->length != 1) {
i2c_write(dev, msg->data[msg->xferred++]);
}
}
sr1 = sr2 = 0;
}
/*
* EV8: Master transmitter
* Transmit buffer empty, but we haven't finished transmitting the last
* byte written.
*/
if ((sr1 & I2C_SR1_TXE) && !(sr1 & I2C_SR1_BTF)) {
I2C_CRUMB(TXE_ONLY, 0, 0);
if (dev->msgs_left) {
i2c_write(dev, msg->data[msg->xferred++]);
if (msg->xferred == msg->length) {
/*
* End of this message. Turn off TXE/RXNE and wait for
* BTF to send repeated start or stop condition.
*/
i2c_disable_irq(dev, I2C_IRQ_BUFFER);
dev->msgs_left--;
}
} else {
/*
* This should be impossible...
*/
throb();
}
sr1 = sr2 = 0;
}
/*
* EV8_2: Master transmitter
* Last byte sent, program repeated start/stop
*/
if ((sr1 & I2C_SR1_TXE) && (sr1 & I2C_SR1_BTF)) {
I2C_CRUMB(TXE_BTF, 0, 0);
if (dev->msgs_left) {
I2C_CRUMB(TEST, 0, 0);
/*
* Repeated start insanity: We can't disable ITEVTEN or else SB
* won't interrupt, but if we don't disable ITEVTEN, BTF will
* continually interrupt us. What the fuck ST?
*/
i2c_start_condition(dev);
while (!(dev->regs->SR1 & I2C_SR1_SB))
;
dev->msg++;
} else {
i2c_stop_condition(dev);
/*
* Turn off event interrupts to keep BTF from firing until
* the end of the stop condition. Why on earth they didn't
* have a start/stop condition request clear BTF is beyond
* me.
*/
i2c_disable_irq(dev, I2C_IRQ_EVENT);
I2C_CRUMB(STOP_SENT, 0, 0);
dev->state = I2C_STATE_XFER_DONE;
}
sr1 = sr2 = 0;
}
/*
* EV7: Master Receiver
*/
if (sr1 & I2C_SR1_RXNE) {
I2C_CRUMB(RXNE_ONLY, 0, 0);
msg->data[msg->xferred++] = dev->regs->DR;
/*
* EV7_1: Second to last byte in the reception? Set NACK and generate
* stop/restart condition in time for the last byte. We'll get one more
* RXNE interrupt before shutting things down.
*/
if (msg->xferred == (msg->length - 1)) {
i2c_disable_ack(dev);
if (dev->msgs_left > 2) {
i2c_start_condition(dev);
I2C_CRUMB(RXNE_START_SENT, 0, 0);
} else {
i2c_stop_condition(dev);
I2C_CRUMB(RXNE_STOP_SENT, 0, 0);
}
} else if (msg->xferred == msg->length) {
dev->msgs_left--;
if (dev->msgs_left == 0) {
/*
* We're done.
*/
I2C_CRUMB(RXNE_DONE, 0, 0);
dev->state = I2C_STATE_XFER_DONE;
} else {
dev->msg++;
}
}
}
}
void __irq_i2c1_ev(void) {
i2c_irq_handler(&i2c_dev1);
}
void __irq_i2c2_ev(void) {
i2c_irq_handler(&i2c_dev2);
}
/**
* @brief Interrupt handler for I2C error conditions
* @param dev I2C device
* @sideeffect Aborts any pending I2C transactions
*/
static void i2c_irq_error_handler(i2c_dev *dev) {
I2C_CRUMB(ERROR_ENTRY, dev->regs->SR1, dev->regs->SR2);
dev->error_flags = dev->regs->SR2 & (I2C_SR1_BERR |
I2C_SR1_ARLO |
I2C_SR1_AF |
I2C_SR1_OVR);
/* Clear flags */
dev->regs->SR1 = 0;
dev->regs->SR2 = 0;
i2c_stop_condition(dev);
i2c_disable_irq(dev, I2C_IRQ_BUFFER | I2C_IRQ_EVENT | I2C_IRQ_ERROR);
dev->state = I2C_STATE_ERROR;
}
void __irq_i2c1_er(void) {
i2c_irq_error_handler(&i2c_dev1);
}
void __irq_i2c2_er(void) {
i2c_irq_error_handler(&i2c_dev2);
}
/**
* @brief Reset an I2C bus.
*
* Reset is accomplished by clocking out pulses until any hung slaves
* release SDA and SCL, then generating a START condition, then a STOP
* condition.
*
* @param dev I2C device
*/
void i2c_bus_reset(const i2c_dev *dev) {
/* Release both lines */
gpio_write_bit(dev->gpio_port, dev->scl_pin, 1);
gpio_write_bit(dev->gpio_port, dev->sda_pin, 1);
gpio_set_mode(dev->gpio_port, dev->scl_pin, GPIO_OUTPUT_OD);
gpio_set_mode(dev->gpio_port, dev->sda_pin, GPIO_OUTPUT_OD);
/*
* Make sure the bus is free by clocking it until any slaves release the
* bus.
*/
while (!gpio_read_bit(dev->gpio_port, dev->sda_pin)) {
/* Wait for any clock stretching to finish */
while (!gpio_read_bit(dev->gpio_port, dev->scl_pin))
;
delay_us(10);
/* Pull low */
gpio_write_bit(dev->gpio_port, dev->scl_pin, 0);
delay_us(10);
/* Release high again */
gpio_write_bit(dev->gpio_port, dev->scl_pin, 1);
delay_us(10);
}
/* Generate start then stop condition */
gpio_write_bit(dev->gpio_port, dev->sda_pin, 0);
delay_us(10);
gpio_write_bit(dev->gpio_port, dev->scl_pin, 0);
delay_us(10);
gpio_write_bit(dev->gpio_port, dev->scl_pin, 1);
delay_us(10);
gpio_write_bit(dev->gpio_port, dev->sda_pin, 1);
}
/**
* @brief Initialize an I2C device and reset its registers to their
* default values.
* @param dev Device to initialize.
*/
void i2c_init(i2c_dev *dev) {
rcc_reset_dev(dev->clk_id);
rcc_clk_enable(dev->clk_id);
}
/**
* @brief Initialize an I2C device as bus master
* @param dev Device to enable
* @param flags Bitwise or of the following I2C options:
* I2C_FAST_MODE: 400 khz operation,
* I2C_DUTY_16_9: 16/9 Tlow/Thigh duty cycle (only applicable for
* fast mode),
* I2C_BUS_RESET: Reset the bus and clock out any hung slaves on
* initialization,
* I2C_10BIT_ADDRESSING: Enable 10-bit addressing,
* I2C_REMAP: Remap I2C1 to SCL/PB8 SDA/PB9.
*/
void i2c_master_enable(i2c_dev *dev, uint32 flags) {
#define I2C_CLK (STM32_PCLK1/1000000)
uint32 ccr = 0;
uint32 trise = 0;
/* PE must be disabled to configure the device */
ASSERT(!(dev->regs->CR1 & I2C_CR1_PE));
if ((dev == I2C1) && (flags & I2C_REMAP)) {
afio_remap(AFIO_REMAP_I2C1);
I2C1->sda_pin = 9;
I2C1->scl_pin = 8;
}
/* Reset the bus. Clock out any hung slaves. */
if (flags & I2C_BUS_RESET) {
i2c_bus_reset(dev);
}
/* Turn on clock and set GPIO modes */
i2c_init(dev);
gpio_set_mode(dev->gpio_port, dev->sda_pin, GPIO_AF_OUTPUT_OD);
gpio_set_mode(dev->gpio_port, dev->scl_pin, GPIO_AF_OUTPUT_OD);
/* I2C1 and I2C2 are fed from APB1, clocked at 36MHz */
i2c_set_input_clk(dev, I2C_CLK);
if (flags & I2C_FAST_MODE) {
ccr |= I2C_CCR_FS;
if (flags & I2C_DUTY_16_9) {
/* Tlow/Thigh = 16/9 */
ccr |= I2C_CCR_DUTY;
ccr |= STM32_PCLK1/(400000 * 25);
} else {
/* Tlow/Thigh = 2 */
ccr |= STM32_PCLK1/(400000 * 3);
}
trise = (300 * (I2C_CLK)/1000) + 1;
} else {
/* Tlow/Thigh = 1 */
ccr = STM32_PCLK1/(100000 * 2);
trise = I2C_CLK + 1;
}
/* Set minimum required value if CCR < 1*/
if ((ccr & I2C_CCR_CCR) == 0) {
ccr |= 0x1;
}
i2c_set_clk_control(dev, ccr);
i2c_set_trise(dev, trise);
/* Enable event and buffer interrupts */
nvic_irq_enable(dev->ev_nvic_line);
nvic_irq_enable(dev->er_nvic_line);
i2c_enable_irq(dev, I2C_IRQ_EVENT | I2C_IRQ_BUFFER | I2C_IRQ_ERROR);
/*
* Important STM32 Errata:
*
* See STM32F10xx8 and STM32F10xxB Errata sheet (Doc ID 14574 Rev 8),
* Section 2.11.1, 2.11.2.
*
* 2.11.1:
* When the EV7, EV7_1, EV6_1, EV6_3, EV2, EV8, and EV3 events are not
* managed before the current byte is being transferred, problems may be
* encountered such as receiving an extra byte, reading the same data twice
* or missing data.
*
* 2.11.2:
* In Master Receiver mode, when closing the communication using
* method 2, the content of the last read data can be corrupted.
*
* If the user software is not able to read the data N-1 before the STOP
* condition is generated on the bus, the content of the shift register
* (data N) will be corrupted. (data N is shifted 1-bit to the left).
*
* ----------------------------------------------------------------------
*
* In order to ensure that events are not missed, the i2c interrupt must
* not be preempted. We set the i2c interrupt priority to be the highest
* interrupt in the system (priority level 0). All other interrupts have
* been initialized to priority level 16. See nvic_init().
*/
nvic_irq_set_priority(dev->ev_nvic_line, 0);
nvic_irq_set_priority(dev->er_nvic_line, 0);
/* Make it go! */
i2c_peripheral_enable(dev);
dev->state = I2C_STATE_IDLE;
}
/**
* @brief Process an i2c transaction.
*
* Transactions are composed of one or more i2c_msg's, and may be read
* or write tranfers. Multiple i2c_msg's will generate a repeated
* start in between messages.
*
* @param dev I2C device
* @param msgs Messages to send/receive
* @param num Number of messages to send/receive
* @param timeout Bus idle timeout in milliseconds before aborting the
* transfer. 0 denotes no timeout.
* @return 0 on success,
* I2C_ERROR_PROTOCOL if there was a protocol error,
* I2C_ERROR_TIMEOUT if the transfer timed out.
*/
int32 i2c_master_xfer(i2c_dev *dev,
i2c_msg *msgs,
uint16 num,
uint32 timeout) {
int32 rc;
ASSERT(dev->state == I2C_STATE_IDLE);
dev->msg = msgs;
dev->msgs_left = num;
dev->timestamp = systick_uptime();
dev->state = I2C_STATE_BUSY;
i2c_enable_irq(dev, I2C_IRQ_EVENT);
i2c_start_condition(dev);
rc = wait_for_state_change(dev, I2C_STATE_XFER_DONE, timeout);
if (rc < 0) {
goto out;
}
dev->state = I2C_STATE_IDLE;
out:
return rc;
}
/**
* @brief Wait for an I2C event, or time out in case of error.
* @param dev I2C device
* @param state I2C_state state to wait for
* @param timeout Timeout, in milliseconds
* @return 0 if target state is reached, a negative value on error.
*/
static inline int32 wait_for_state_change(i2c_dev *dev,
i2c_state state,
uint32 timeout) {
i2c_state tmp;
while (1) {
tmp = dev->state;
if (tmp == I2C_STATE_ERROR) {
return I2C_STATE_ERROR;
}
if (tmp == state) {
return 0;
}
if (timeout) {
if (systick_uptime() > (dev->timestamp + timeout)) {
/* TODO: overflow? */
/* TODO: racy? */
return I2C_ERROR_TIMEOUT;
}
}
}
}