px_m41t00.h : Driver for an ST M41T00 Real Time Clock

Description

This driver interface with an ST M41T00 RTC using I2C.

File(s):

• devices/rtc/inc/px_m41t00.h
• devices/rtc/src/px_m41t00.c

Reference:

• ST M41T00M6E datasheet

Example:

#include "px_defs.h"
#include "px_uart.h"
#include "px_uart_stdio.h"
#include "px_pgm_P.h"
#include "px_i2c.h"
#include "px_m41t00.h"
 
// Declare I2C handle structure
px_i2c_handle_t  px_i2c_handle;
 
// Declare UART handle structure
px_uart_handle_t px_uart_handle;
 
px_m41t00_time_t time = 
{
    .sec          = 0,
    .min          = 0,
    .hour         = 12,
    .day_of_week  = 1,
    .day_of_month = 1,
    .month        = 4,
    .year         = 7
};
 
void px_m41t00_test(void)
{
    uint8_t sec;
 
    // Initialise modules
    px_i2c_init();
    px_uart_init();
 
    // Open I2C Slave handle
    px_i2c_open(&px_i2c_handle, PX_I2C_NR_0, PX_M41T00_SLA_ADR);
    px_m41t00_init(&px_i2c_handle);
 
    // Open UART0 @ 115200 BAUD, 8 data bits, no parity, 1 stop bit
    px_uart_open2(&px_uart_handle,
                  PX_UART_NR_0, 
                  115200, 
                  PX_UART_DATA_BITS_8, 
                  PX_UART_PARITY_NONE, 
                  PX_UART_STOP_BITS_1);
 
    // Direct stdio to UART0
    px_uart_stdio_init(&px_uart_handle);
 
    // Enable interrupts
    px_interrupts_enable();
 
    // Set time and date
    if(!px_m41t00_set_time(&time))
    {
        PX_PRINTF_P("Unable to set time!\n");
        while(true) {;}
    }
  
    // Loop forever
    while(true)
    {
        // Remember current seconds value
        sec = time.sec;
        // Fetch new time
        if(!px_m41t00_get_time(&time))
        {
            PX_PRINTF_P("Unable to set time!\n");
            while(true) {;}
        }
        // See if a second has elapsed
        if(time.sec != sec)
        {
            // Display the new date and time
            PX_PRINTF_P("%02d-%02d-%02d %02dh%02d:%02d\n",
                        time.year,
                        time.month,
                        time.day_of_month,
                        time.hour,
                        time.min,
                        time.sec);
        }
    }    
}

Data Structures
struct	px_m41t00_time_t
	Structure to store time and date. More...

Macros
#define	PX_M41T00_SLA_ADR   0x68
	I2C Slave Address. More...

Functions
void	px_m41t00_init (px_i2c_handle_t *px_i2c_handle)
	Initialise driver. More...
bool	px_m41t00_get_time (px_m41t00_time_t *px_rtc_time)
	Get RTC time using I2C driver. More...
bool	px_m41t00_set_time (const px_m41t00_time_t *px_rtc_time)
	Set RTC time using I2C driver. More...

---

Data Structure Documentation

px_m41t00_time_t

struct px_m41t00_time_t

Structure to store time and date.

Definition at line 53 of file px_m41t00.h.

Data Fields
uint8_t	sec	Seconds: 0 to 59.
uint8_t	min	Minutes: 0 to 59.
uint8_t	hour	Hours: 0 to 23.
uint8_t	day_of_week	Day of Week: 1 to 7.
uint8_t	day_of_month	Days of Month: 1 to 31 (depending on month)
uint8_t	month	Months: 1 to 12.
uint8_t	year	Years: 00 to 99.

Macro Definition Documentation

PX_M41T00_SLA_ADR

#define PX_M41T00_SLA_ADR   0x68

I2C Slave Address.

Definition at line 49 of file px_m41t00.h.

Function Documentation

px_m41t00_init()

void px_m41t00_init

(

px_i2c_handle_t *

px_i2c_handle

)

Initialise driver.

Parameters

px_i2c_handle

Pointer to I2C driver handle

Definition at line 136 of file px_m41t00.c.

px_m41t00_get_time()

bool px_m41t00_get_time

(

px_m41t00_time_t *

px_rtc_time

)

Get RTC time using I2C driver.

Parameters

[out]

px_rtc_time

Pointer to a structure that will contain the new time.

Return values

true	Time succesfully retrieved and copied into structure.
false	Unable to get the time (I2C communication error) or timer has been stopped (new battery inserted)

Definition at line 141 of file px_m41t00.c.

px_m41t00_set_time()

bool px_m41t00_set_time

(

const px_m41t00_time_t *

px_rtc_time

)

Set RTC time using I2C driver.

Parameters

[in]

px_rtc_time

Pointer to a structure containing the new time.

Return values

true	Time succesfully set
false	Unable to set the time (I2C communication error)

Definition at line 182 of file px_m41t00.c.