i2c_common_v2.c

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/** @addtogroup i2c_file I2C peripheral API
 * @ingroup peripheral_apis
 */
 
/*
 * This file is part of the libopencm3 project.
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <libopencm3/stm32/i2c.h>
#include <libopencm3/stm32/rcc.h>
 
/**@{*/
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Peripheral Enable.
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
 
void i2c_peripheral_enable(uint32_t i2c)
{
        I2C_CR1(i2c) |= I2C_CR1_PE;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Peripheral Disable.
 *
 * This must not be reset while in Master mode until a communication has
 * finished. In Slave mode, the peripheral is disabled only after communication
 * has ended.
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
 
void i2c_peripheral_disable(uint32_t i2c)
{
        I2C_CR1(i2c) &= ~I2C_CR1_PE;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Send Start Condition.
 *
 * If in Master mode this will cause a restart condition to occur at the end of
 * the current transmission. If in Slave mode, this will initiate a start
 * condition when the current bus activity is completed.
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
 
void i2c_send_start(uint32_t i2c)
{
        I2C_CR2(i2c) |= I2C_CR2_START;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Send Stop Condition.
 *
 * After the current byte transfer this will initiate a stop condition if in
 * Master mode, or simply release the bus if in Slave mode.
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
 
void i2c_send_stop(uint32_t i2c)
{
        I2C_CR2(i2c) |= I2C_CR2_STOP;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Clear Stop Flag.
 *
 * Clear the "Send Stop" flag in the I2C config register
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
void i2c_clear_stop(uint32_t i2c)
{
        I2C_ICR(i2c) |= I2C_ICR_STOPCF;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Set the 7 bit Slave Address for the Peripheral.
 *
 * This sets an address for Slave mode operation, in 7 bit form.
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 * @param[in] slave Unsigned int8. Slave address 0...127.
 */
 
void i2c_set_own_7bit_slave_address(uint32_t i2c, uint8_t slave)
{
        I2C_OAR1(i2c) = (uint16_t)(slave << 1);
        I2C_OAR1(i2c) &= ~I2C_OAR1_OA1MODE;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Set the 10 bit Slave Address for the Peripheral.
 *
 * This sets an address for Slave mode operation, in 10 bit form.
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 * @param[in] slave Unsigned int16. Slave address 0...1023.
 */
 
void i2c_set_own_10bit_slave_address(uint32_t i2c, uint16_t slave)
{
        I2C_OAR1(i2c) = (uint16_t)(I2C_OAR1_OA1MODE | slave);
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Send Data.
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 * @param[in] data Unsigned int8. Byte to send.
 */
 
void i2c_send_data(uint32_t i2c, uint8_t data)
{
        I2C_TXDR(i2c) = data;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Get Data.
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
uint8_t i2c_get_data(uint32_t i2c)
{
        return I2C_RXDR(i2c) & 0xff;
}
 
void i2c_enable_analog_filter(uint32_t i2c)
{
        I2C_CR1(i2c) &= ~I2C_CR1_ANFOFF;
}
 
void i2c_disable_analog_filter(uint32_t i2c)
{
        I2C_CR1(i2c) |= I2C_CR1_ANFOFF;
}
 
/**
 * Set the I2C digital filter.
 * These bits are used to configure the digital noise filter on SDA and
 * SCL input. The digital filter will filter spikes with a length of up
 * to dnf_setting * I2CCLK clocks
 * @param i2c peripheral of interest
 * @param dnf_setting 0 to disable, else 1..15 i2c clocks
 */
void i2c_set_digital_filter(uint32_t i2c, uint8_t dnf_setting)
{
        I2C_CR1(i2c) = (I2C_CR1(i2c) & ~(I2C_CR1_DNF_MASK << I2C_CR1_DNF_SHIFT)) |
                (dnf_setting << I2C_CR1_DNF_SHIFT);
}
 
/* t_presc= (presc+1)*t_i2cclk */
void i2c_set_prescaler(uint32_t i2c, uint8_t presc)
{
        I2C_TIMINGR(i2c) = (I2C_TIMINGR(i2c) & ~I2C_TIMINGR_PRESC_MASK) |
                           (presc << I2C_TIMINGR_PRESC_SHIFT);
}
 
void i2c_set_data_setup_time(uint32_t i2c, uint8_t s_time)
{
        I2C_TIMINGR(i2c) = (I2C_TIMINGR(i2c) & ~I2C_TIMINGR_SCLDEL_MASK) |
                           (s_time << I2C_TIMINGR_SCLDEL_SHIFT);
}
 
void i2c_set_data_hold_time(uint32_t i2c, uint8_t h_time)
{
        I2C_TIMINGR(i2c) = (I2C_TIMINGR(i2c) & ~I2C_TIMINGR_SDADEL_MASK) |
                           (h_time << I2C_TIMINGR_SDADEL_SHIFT);
}
 
void i2c_set_scl_high_period(uint32_t i2c, uint8_t period)
{
        I2C_TIMINGR(i2c) = (I2C_TIMINGR(i2c) & ~I2C_TIMINGR_SCLH_MASK) |
                           (period << I2C_TIMINGR_SCLH_SHIFT);
}
 
void i2c_set_scl_low_period(uint32_t i2c, uint8_t period)
{
        I2C_TIMINGR(i2c) = (I2C_TIMINGR(i2c) & ~I2C_TIMINGR_SCLL_MASK) |
                           (period << I2C_TIMINGR_SCLL_SHIFT);
}
 
void i2c_enable_stretching(uint32_t i2c)
{
        I2C_CR1(i2c) &= ~I2C_CR1_NOSTRETCH;
}
 
void i2c_disable_stretching(uint32_t i2c)
{
        I2C_CR1(i2c) |= I2C_CR1_NOSTRETCH;
}
 
void i2c_set_7bit_addr_mode(uint32_t i2c)
{
        I2C_CR2(i2c) &= ~I2C_CR2_ADD10;
}
 
void i2c_set_10bit_addr_mode(uint32_t i2c)
{
        I2C_CR2(i2c) |= I2C_CR2_ADD10;
}
 
void i2c_set_7bit_address(uint32_t i2c, uint8_t addr)
{
        I2C_CR2(i2c) = (I2C_CR2(i2c) & ~I2C_CR2_SADD_7BIT_MASK) |
                       ((addr & 0x7F) << I2C_CR2_SADD_7BIT_SHIFT);
}
 
void i2c_set_10bit_address(uint32_t i2c, uint16_t addr)
{
        I2C_CR2(i2c) = (I2C_CR2(i2c) & ~I2C_CR2_SADD_10BIT_MASK) |
                       ((addr & 0x3FF) << I2C_CR2_SADD_10BIT_SHIFT);
}
 
void i2c_set_write_transfer_dir(uint32_t i2c)
{
        I2C_CR2(i2c) &= ~I2C_CR2_RD_WRN;
}
 
void i2c_set_read_transfer_dir(uint32_t i2c)
{
        I2C_CR2(i2c) |= I2C_CR2_RD_WRN;
}
 
void i2c_set_bytes_to_transfer(uint32_t i2c, uint32_t n_bytes)
{
        I2C_CR2(i2c) = (I2C_CR2(i2c) & ~I2C_CR2_NBYTES_MASK) |
                       (n_bytes << I2C_CR2_NBYTES_SHIFT);
}
 
bool i2c_is_start(uint32_t i2c)
{
        return (I2C_CR2(i2c) & I2C_CR2_START);
}
 
void i2c_enable_autoend(uint32_t i2c)
{
        I2C_CR2(i2c) |= I2C_CR2_AUTOEND;
}
 
void i2c_disable_autoend(uint32_t i2c)
{
        I2C_CR2(i2c) &= ~I2C_CR2_AUTOEND;
}
 
bool i2c_nack(uint32_t i2c)
{
        return (I2C_ISR(i2c) & I2C_ISR_NACKF);
}
 
bool i2c_busy(uint32_t i2c)
{
        return (I2C_ISR(i2c) & I2C_ISR_BUSY);
}
 
bool i2c_transmit_int_status(uint32_t i2c)
{
        return (I2C_ISR(i2c) & I2C_ISR_TXIS);
}
 
bool i2c_transfer_complete(uint32_t i2c)
{
        return (I2C_ISR(i2c) & I2C_ISR_TC);
}
 
bool i2c_received_data(uint32_t i2c)
{
        return (I2C_ISR(i2c) & I2C_ISR_RXNE);
}
 
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Enable Interrupt
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 * @param[in] interrupt Unsigned int32. Interrupt to enable.
 */
void i2c_enable_interrupt(uint32_t i2c, uint32_t interrupt)
{
        I2C_CR1(i2c) |= interrupt;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Disable Interrupt
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 * @param[in] interrupt Unsigned int32. Interrupt to disable.
 */
void i2c_disable_interrupt(uint32_t i2c, uint32_t interrupt)
{
        I2C_CR1(i2c) &= ~interrupt;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Enable reception DMA
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
void i2c_enable_rxdma(uint32_t i2c)
{
        I2C_CR1(i2c) |= I2C_CR1_RXDMAEN;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Disable reception DMA
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
void i2c_disable_rxdma(uint32_t i2c)
{
        I2C_CR1(i2c) &= ~I2C_CR1_RXDMAEN;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Enable transmission DMA
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
void i2c_enable_txdma(uint32_t i2c)
{
        I2C_CR1(i2c) |= I2C_CR1_TXDMAEN;
}
 
/*---------------------------------------------------------------------------*/
/** @brief I2C Disable transmission DMA
 *
 * @param[in] i2c Unsigned int32. I2C register base address @ref i2c_reg_base.
 */
void i2c_disable_txdma(uint32_t i2c)
{
        I2C_CR1(i2c) &= ~I2C_CR1_TXDMAEN;
}
 
/**
 * Run a write/read transaction to a given 7bit i2c address
 * If both write & read are provided, the read will use repeated start.
 * Both write and read are optional
 * @param i2c peripheral of choice, eg I2C1
 * @param addr 7 bit i2c device address
 * @param w buffer of data to write
 * @param wn length of w
 * @param r destination buffer to read into
 * @param rn number of bytes to read (r should be at least this long)
 */
void i2c_transfer7(uint32_t i2c, uint8_t addr, const uint8_t *w, size_t wn, uint8_t *r, size_t rn)
{
        /*  waiting for busy is unnecessary. read the RM */
        if (wn) {
                i2c_set_7bit_address(i2c, addr);
                i2c_set_write_transfer_dir(i2c);
                i2c_set_bytes_to_transfer(i2c, wn);
                if (rn) {
                        i2c_disable_autoend(i2c);
                } else {
                        i2c_enable_autoend(i2c);
                }
                i2c_send_start(i2c);
 
                while (wn--) {
                        bool wait = true;
                        while (wait) {
                                if (i2c_transmit_int_status(i2c)) {
                                        wait = false;
                                }
                                while (i2c_nack(i2c)); /* FIXME Some error */
                        }
                        i2c_send_data(i2c, *w++);
                }
                /* not entirely sure this is really necessary.
                 * RM implies it will stall until it can write out the later bits
                 */
                if (rn) {
                        while (!i2c_transfer_complete(i2c));
                }
        }
 
        if (rn) {
                /* Setting transfer properties */
                i2c_set_7bit_address(i2c, addr);
                i2c_set_read_transfer_dir(i2c);
                i2c_set_bytes_to_transfer(i2c, rn);
                /* start transfer */
                i2c_send_start(i2c);
                /* important to do it afterwards to do a proper repeated start! */
                i2c_enable_autoend(i2c);
 
                for (size_t i = 0; i < rn; i++) {
                        while (i2c_received_data(i2c) == 0);
                        r[i] = i2c_get_data(i2c);
                }
        }
}
 
 
/**
 * Set the i2c communication speed.
 * NOTE: 1MHz mode not yet implemented!
 * Min clock speed: 8MHz for FM, 2Mhz for SM,
 * @param i2c peripheral, eg I2C1
 * @param speed one of the listed speed modes @ref i2c_speeds
 * @param clock_megahz i2c peripheral clock speed in MHz. Usually, rcc_apb1_frequency / 1e6
 */
void i2c_set_speed(uint32_t i2c, enum i2c_speeds speed, uint32_t clock_megahz)
{
        int prescaler;
        switch(speed) {
        case i2c_speed_fmp_1m:
                /* FIXME - add support for this mode! */
                break;
        case i2c_speed_fm_400k:
                /* target 8Mhz input, so tpresc = 125ns */
                prescaler = clock_megahz / 8 - 1;
                i2c_set_prescaler(i2c, prescaler);
                i2c_set_scl_low_period(i2c, 10-1); // 1250ns
                i2c_set_scl_high_period(i2c, 4-1); // 500ns
                i2c_set_data_hold_time(i2c, 3); // 375ns
                i2c_set_data_setup_time(i2c, 4-1); // 500ns
                break;
        default:
                /* fall back to standard mode */
        case i2c_speed_sm_100k:
                /* target 4Mhz input, so tpresc = 250ns */
                prescaler = (clock_megahz / 4) - 1;
                i2c_set_prescaler(i2c, prescaler);
                i2c_set_scl_low_period(i2c, 20-1); // 5usecs
                i2c_set_scl_high_period(i2c, 16-1); // 4usecs
                i2c_set_data_hold_time(i2c, 2); // 0.5usecs
                i2c_set_data_setup_time(i2c, 5-1); // 1.25usecs
                break;
        }
}
 
/**@}*/