read specific address over I2C, read seconds, use doxygen documentation
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@ -12,9 +12,12 @@
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/* Copyright (c) 2016 King Kévin <kingkevin@cuvoodoo.info> */
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/* this library handles communication with the I2C RTC IC Maxim DS1307 */
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/* peripherals used: I2C (check source for details) */
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/** @file rtc_ds1307.c
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @date 2016
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* @brief this library handles communication with the I2C RTC IC Maxim DS1307
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* peripherals used: I2C @ref rtc_ds1307_i2c
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*/
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/* standard libraries */
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#include <stdint.h> // standard integer types
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@ -28,18 +31,28 @@
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#include <libopencm3/cm3/nvic.h> // interrupt handler
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#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
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#include "global.h" // global utilities
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#include "rtc_ds1307.h" // RTC header and definitions
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/* which I2C to use */
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/** @defgroup trc_ds1307_i2c I2C port used to communication with the DS1307 RTC IC
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* @{
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*/
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/** I2C peripheral */
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#define I2C I2C1
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/** I2C peripheral clock */
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#define I2C_RCC RCC_I2C1
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/** I2C peripheral interrupt */
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#define I2C_IRQ NVIC_I2C1_IRQ
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/** I2C peripheral port */
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#define I2C_PORT GPIOB
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#define I2C_PIN_SDA GPIO_I2C1_SDA // on PB7
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#define I2C_PIN_SCL GPIO_I2C1_SCL // on PB6
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#define I2C_ADDR 0b1101000 // DS1307 fixed slave address
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/** I2C peripheral data pin (PB7) */
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#define I2C_PIN_SDA GPIO_I2C1_SDA
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/** I2C peripheral clock pin (PB6) */
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#define I2C_PIN_SCL GPIO_I2C1_SCL
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/** @} */
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/** DS1307 I2C address (fixed) */
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#define I2C_ADDR 0b1101000
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/* setup communication with RTC IC */
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void rtc_setup(void)
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{
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/* enable peripheral */
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@ -57,23 +70,35 @@ void rtc_setup(void)
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i2c_peripheral_enable(I2C); // enable I2C after configuration completed
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}
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/* read memory from RTC IC
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* read <len> data into <data>
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* return if read succeeded */
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static bool rtc_read_memory(uint8_t* data, size_t len)
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/** @brief read memory from RTC IC
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* @param[in] addr start address for memory to read
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* @param[out] data buffer to store read memory
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* @param[in] len number of byte to read from the memory
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* @return if read succeeded
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*/
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static bool rtc_read_memory(uint8_t addr, uint8_t* data, size_t len)
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{
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bool to_return = false; // return if read succeeded
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if (data==NULL || len==0) { // verify there it data to be read
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goto error;
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}
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i2c_send_start(I2C); // send start condition to start transaction
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while (!(I2C_SR1(I2C) & I2C_SR1_SB)); // wait until start bit is transmitted
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while (!(I2C_SR1(I2C) & I2C_SR1_SB)); // wait until start condition is transmitted
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if (!(I2C_SR2(I2C) & I2C_SR2_MSL)) { // verify if in master mode
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goto error;
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}
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i2c_send_7bit_address(I2C, I2C_ADDR, I2C_READ); // transmit address
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i2c_send_7bit_address(I2C, I2C_ADDR, I2C_WRITE); // select slave
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while (!(I2C_SR1(I2C) & I2C_SR1_ADDR)); // wait until address is transmitted
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if (I2C_SR2(I2C) & I2C_SR2_TRA) { // verify we are in receive mode (and read SR2 to clear ADDR)
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if (!((I2C_SR2(I2C) & I2C_SR2_TRA))) { // verify we are in transmit mode (and read SR2 to clear ADDR)
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goto error;
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}
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i2c_send_data(I2C, addr); // send memory address we want to read
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while (!(I2C_SR1(I2C) & I2C_SR1_TxE)); // wait until byte has been transmitted
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i2c_send_start(I2C); // send restart condition to switch from write to read mode
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while (!(I2C_SR1(I2C) & I2C_SR1_SB)); // wait until start condition is transmitted
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i2c_send_7bit_address(I2C, I2C_ADDR, I2C_READ); // select slave
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while (!(I2C_SR1(I2C) & I2C_SR1_ADDR)); // wait until address is transmitted
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if ((I2C_SR2(I2C) & I2C_SR2_TRA)) { // verify we are in read mode (and read SR2 to clear ADDR)
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goto error;
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}
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for (size_t i=0; i<len; i++) { // read bytes
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@ -95,10 +120,11 @@ error:
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return to_return;
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}
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/* read seconds (0-59) from RTC IC */
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uint8_t rtc_read_seconds(void)
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{
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uint8_t to_return = 0; // seconds to return
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rtc_read_memory(&to_return, 1); // read a single byte to test
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uint8_t data[1] = {0}; // to read data from I2C
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rtc_read_memory(0, data, LENGTH(data)); // read a single byte to test
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to_return = ((data[0]&0x70)>>4)*10+(data[0]&0x0f); // convert BCD coding into seconds
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return to_return;
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}
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@ -12,12 +12,19 @@
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/* Copyright (c) 2016 King Kévin <kingkevin@cuvoodoo.info> */
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/* this library handles communication with the I2C RTC IC Maxim DS1307 */
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/* peripherals used: I2C (check source for details) */
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/** @file rtc_ds1307.h
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @date 2016
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* @brief this library handles communication with the I2C RTC IC Maxim DS1307
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* peripherals used: I2C @ref rtc_ds1307_i2c
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*/
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#pragma once
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/* setup communication with RTC IC */
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/** @brief setup communication with RTC IC
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* configure the I2C port defined in the sources
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*/
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void rtc_setup(void);
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/* read seconds (0-59) from RTC IC */
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/** @brief read seconds (0-59) from RTC IC
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* @return the number of seconds of the current time
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*/
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uint8_t rtc_read_seconds(void);
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