Time and Date

From NutWiki

1 Test Environments
2 Description
3 Source Code
4 Output
5 Details
6 Description
7 Source Code
8 Details
9 See also
10 External Links

Test Environments

	Hardware Comments	Nut/OS 4.6.3	Nut/OS 4.6.4	Nut/OS 4.7.4	Nut/OS 4.8.0	Nut/OS 4.8.7
Ethernut 1.3 H	No RTC hardware. Date and time settings are lost after reset.	OK	OK Binaries	OK Binaries	OK Binaries	OK Binaries Compiler: AVR-GCC 4.3.2
Ethernut 2.1 B	No RTC hardware. Date and time settings are lost after reset.	OK	OK Binaries	OK Binaries	OK Binaries	OK Binaries Compiler: AVR-GCC 4.3.2
Ethernut 3.0 E		OK	OK Binaries	OK Binaries	OK Binaries	OK Binaries Compiler: ARM-GCC 4.3.3
EIR 1.0	Set jumper JP1 to UART mode.	OK Add outr(PIOA_PDR, _BV(PA5_RXD0_A) \| _BV(PA6_TXD0_A)); immediately after NutRegisterDevice().	OK Binaries	OK Binaries	OK Binaries
Compiler: ARM-GCC 4.2.2 ; AVR-GCC 4.3.0

Description

This is an example on how to build a simple clock with Nut/OS.

Source Code

#include <dev/board.h>
#include <dev/debug.h>
#include <sys/timer.h>
 
#include <stdlib.h>
#include <stdio.h>
#include <io.h>
#include <string.h>
#include <time.h>
 
static char *weekday_name[7] = {
    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
static char *month_name[12] = {
    "January", "February", "March", "April", "May", "June", "July", "August",
    "September", "October", "November", "December"};
 
static void PrintDateTime(CONST struct _tm *stm)
{
    printf("%s, %02d. %s %04d, %02d:%02d:%02d", weekday_name[stm->tm_wday],
        stm->tm_mday, month_name[stm->tm_mon], stm->tm_year + 1900,
        stm->tm_hour, stm->tm_min, stm->tm_sec);
}
 
static void DisplayLocalTime(void)
{
    time_t tt;
    struct _tm *ltm;
 
    while (!kbhit()) {
        tt = time(NULL);
        ltm = localtime(&tt);
        PrintDateTime(ltm);
        printf("\r");
        NutSleep(100);
    }
    putchar('\n');
}
 
int main(void)
{
    u_long baud = 115200;
    NutRegisterDevice(&DEV_UART, 0, 0);
    freopen(DEV_UART_NAME, "w", stdout);
    freopen(DEV_UART_NAME, "r", stdin);
    _ioctl(_fileno(stdout), UART_SETSPEED, &baud);
 
#ifdef RTC_CHIP
    NutRegisterRtc(&RTC_CHIP);
#endif
 
    DisplayLocalTime();
 
    return 0;
}

Output

Wednesday, 31. December 1969, 19:00:00

Details

The first 9 lines include the required libraries for this program, as usual.

static char *weekday_name[7] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

declares an array of 7 pointers (of type char) and calls the array weekday_name. Each of those pointers point to an adress in memory where the specified strings are stored (e.g. "Sunday").

static char *month_name[12] = {
    "January", "February", "March", "April", "May", "June", "July", "August",
    "September", "October", "November", "December"};

behaves analog.

static void PrintDateTime(CONST struct _tm *stm)

defines a void function called PrintDateTime with a pointer (stm) to the _tm structure as parameter.

printf("%s, %02d. %s %04d, %02d:%02d:%02d", weekday_name[stm->tm_wday],
        stm->tm_mday, month_name[stm->tm_mon], stm->tm_year + 1900,
        stm->tm_hour, stm->tm_min, stm->tm_sec);

Prints out the time and date, stored in the _tm structure. In the case of weekday_name and month_name it replaces the content of the _tm structure, by the corresponding strings.

static void DisplayLocalTime(void)
{
    time_t tt;
    struct _tm *ltm;
 
    while (!kbhit()) {
        tt = time(NULL);
        ltm = localtime(&tt);
        PrintDateTime(ltm);
        printf("\r");
        NutSleep(100);
    }
    putchar('\n');
}

Defines a variable "tt" of the type type_t, which holds the calendar time (seconds since the start of the Unix epoche), and a pointer to the _tm structure.

The following while (!kbhit()) loop cycles as long as no keyboard hit occured, gets the system time (if already stored, passes it to the _tm structure and passes the content of the _tm structure to the PrintTimeDate function.

printf("\r") causes a carriage return, followed by a NutSleep(100).
By that the output line gets refreshed every 100ms.

int main(void)

declares the main function, the first function that will be executed.

u_long baud = 115200;

Defines a variable of the type u_long (32bit long), calls it "baud" and assigns the value 115200 to it.

The following four lines register the UART device, open it, assign stdout and stdin to it and set the baudrate.

#ifdef RTC_CHIP
    NutRegisterRtc(&RTC_CHIP);
#endif

registers the boards RTC(Real Time Clock) chip (if available), that holds the calender time. Thus it is powerded by a Goldcap capacitor it even stores the time, when the main power supply is disconnected, for some time.(Ethernut 3 only)

Description

With this example it is not only possible to display but also to set the time.

Source Code

#include <dev/board.h>
#include <dev/debug.h>
 
#include <sys/version.h>
#include <sys/timer.h>
 
#include <stdlib.h>
#include <stdio.h>
#include <io.h>
#include <string.h>
#include <time.h>
 
static char *weekday_name[7] = {
    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
static char *month_name[12] = {
    "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
 
static void PrintDateTime(CONST struct _tm *stm)
{
    printf("%s, %02d. %s %04d, %02d:%02d:%02d",
        weekday_name[stm->tm_wday],
        stm->tm_mday, month_name[stm->tm_mon], stm->tm_year + 1900,
        stm->tm_hour, stm->tm_min, stm->tm_sec);
}
 
static int EnterDate(struct _tm *stm)
{
    int year;
    int mon;
    int mday;
 
    printf("Enter date\n");
 
    printf("Year(YYYY): ");
    scanf("%d", &year);
    stm->tm_year = year - 1900;
    printf("%04d", stm->tm_year + 1900);
 
    printf("\nMonth(MM): ");
    scanf("%d", &mon);
    stm->tm_mon = mon - 1;
    printf("%02d", stm->tm_mon + 1);
 
    printf("\nDay(DD): ");
    scanf("%d", &mday);
    stm->tm_mday = mday;
    printf("%02d  (%s)", stm->tm_mday, weekday_name[stm->tm_wday]);
 
    putchar('\n');
 
    return 0;
}
 
static int EnterTime(struct _tm *stm)
{
    int hour;
    int minute;
    int second;
 
    printf("Enter time, use 24h format\n");
 
    printf("Hours: ");
    scanf("%d", &hour);
    stm->tm_hour = hour;
    printf("%02d", stm->tm_hour);
 
    printf("\nMinutes: ");
    scanf("%d", &minute);
    stm->tm_min = minute;
    printf("%02d", stm->tm_min);
 
    printf("\nSeconds: ");
    scanf("%d", &second);
    stm->tm_sec = second;
    printf("%02d\n\n", stm->tm_sec);
 
    putchar('\n');
 
    return 0;
}
 
static void SetLocalTime(void)
{
    struct _tm ltm;
    time_t now;
 
    time(&now);
    memcpy(&ltm, localtime(&now), sizeof(ltm));
 
    if (EnterDate(&ltm) == 0 && EnterTime(&ltm) == 0) {
        now = mktime(&ltm);
        stime(&now);
    }
}
 
static void DisplayLocalTime(void)
{
    time_t tt;
    struct _tm *ltm;
 
    while (!kbhit()) {
        tt = time(NULL);
        ltm = localtime(&tt);
        PrintDateTime(ltm);
 
        printf("\r");
 
        NutSleep(100);
    }
    putchar('\n');
}
 
int main(void)
{
    u_long baud = 115200;
    NutRegisterDevice(&DEV_UART, 0, 0);
    freopen(DEV_UART_NAME, "w", stdout);
    freopen(DEV_UART_NAME, "r", stdin);
    _ioctl(_fileno(stdout), UART_SETSPEED, &baud);
 
    #ifdef RTC_CHIP
        (NutRegisterRtc(&RTC_CHIP));
    #endif
 
    SetLocalTime();
    DisplayLocalTime();
 
    return 0;
}

Details

This example contains 3 additional functions: EnterDate, EnterTime and SetLocalTime

static int EnterDate(struct _tm *stm)

defines a function with a pointer to the _tm structure as parameter.

printf("Hours: ");
scanf("%d", &hour);
stm->tm_hour = hour;
printf("%02d", stm->tm_hour);
 
printf("\nMinutes: ");
scanf("%d", &minute);
stm->tm_min = minute;
printf("%02d", stm->tm_min);
 
printf("\nSeconds: ");
scanf("%d", &second);
stm->tm_sec = second;
printf("%02d\n\n", stm->tm_sec);

The scanf statements store the user input in a local variable. Then the value gets stored in the _tm structure through the stm pointer.

static int EnterTime(struct _tm *stm)

behaves analog.

static void SetLocalTime(void)
{
    struct _tm ltm;
    time_t now;
 
    time(&now);
    memcpy(&ltm, localtime(&now), sizeof(ltm));
 
    if (EnterDate(&ltm) == 0 && EnterTime(&ltm) == 0) {
        now = mktime(&ltm);
        stime(&now);
    }
}

defines a variable "ltm" of the structure type _tm and a variable "now" of type time_t.

time(&now) stores the current calender time in now.

memcopy now copies the return of localtime(&now)(which converts calender time to a broken-down local time) via ltm to the _tm structure.

Then, within the if statement, the functions EnterDate(&ltm) and EnterTime(&ltm) are called. After that mktime converts the content of the _tm structure in calender time, which is then stored by time(&now) in the RTC.

External Links

X1226/X1286 Realtime Clock And Calendar About the RTC chip on Ethernut 3.0.

Languages:

English

Retrieved from "http://www.ethernet-mp3.de/nutwiki/Time_and_Date"

Category: Code Snippets

Time and Date

From NutWiki

Contents

Test Environments

Description

Source Code

Output

Details

Description

Source Code

Details

See also

External Links

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