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‎See also

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== Test Environments ==

{| class="smalldiv"
| style="background-color:#F6F9ED" |
| style="background-color:#F6F9ED" | Hardware Comments
| style="background-color:#F6F9ED" | '''Nut/OS 4.6.3'''
| style="background-color:#F6F9ED" | '''Nut/OS 4.6.4'''
| style="background-color:#F6F9ED" | '''Nut/OS 4.7.4'''
| style="background-color:#F6F9ED" | '''Nut/OS 4.8.0'''
| style="background-color:#F6F9ED" | '''Nut/OS 4.8.7'''
|-
| Ethernut 1.3 H
| No RTC hardware. Date and time settings are lost after reset.
| OK
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-enut13H-nutos-4.6.4.zip '''Binaries''']
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-enut13H-nutos-4.7.4.zip '''Binaries''']
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-enut13H-nutos-4.8.0.zip '''Binaries''']
| OK [[Media:Time-and-date-enut13H-nutos-4.8.7.zip|'''Binaries''']] '''Compiler:''' AVR-GCC 4.3.2
|-
| Ethernut 2.1 B
| No RTC hardware. Date and time settings are lost after reset.
| OK
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-enut21B-nutos-4.6.4.zip '''Binaries''']
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-enut21B-nutos-4.7.4.zip '''Binaries''']
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-enut21B-nutos-4.8.0.zip '''Binaries''']
| OK [[Media:Time-and-date-enut21B-nutos-4.8.7.zip|'''Binaries''']] '''Compiler:''' AVR-GCC 4.3.2
|-
| Ethernut 3.0 E
|
| OK
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-enut30E-nutos-4.6.4.zip '''Binaries''']
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-enut30E-nutos-4.7.4.zip '''Binaries''']
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-enut30E-nutos-4.8.0.zip '''Binaries''']
| OK [[Media:Time-and-date-enut30E-nutos-4.8.7.zip|'''Binaries''']] '''Compiler:''' ARM-GCC 4.3.3
|-
| EIR 1.0
| Set jumper JP1 to UART mode.
| OK 
Add 
<source lang="c">
outr(PIOA_PDR, _BV(PA5_RXD0_A) | _BV(PA6_TXD0_A));
</source>
immediately after NutRegisterDevice().
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-EIR1C-nutos-4.6.4.zip '''Binaries''']
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-EIR1C-nutos-4.7.4.zip '''Binaries''']
| OK [http://ethernut.de/arc/WIKI_BINARIES_ZIPPED/time-and-date-EIR1C-nutos-4.8.0.zip '''Binaries''']
|
|-
| id="compilertd" colspan="5" |'''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 ==

<source lang="c">
#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;
}

</source>

== Output ==

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

== Details ==

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

<source lang="C">static char *weekday_name[7] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};</source>
declares an array of 7 pointers (of type char) and calls the array <code>weekday_name</code>.
Each of those pointers point to an adress in memory where the specified strings are stored (e.g. "Sunday").

<source lang="C">static char *month_name[12] = {
"January", "February", "March", "April", "May", "June", "July", "August",
"September", "October", "November", "December"};
</source>behaves analog.

<source lang="C">static void PrintDateTime(CONST struct _tm *stm)</source>

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

<source lang="C">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);
</source>
Prints out the time and date, stored in the <code>_tm</code> structure. In the case of <code>weekday_name</code> and <code>month_name</code> it replaces the content of the <code>_tm</code> structure, by the corresponding strings.

<source lang="C">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');
}
</source>
Defines a variable "tt" of the type <code>type_t</code>, which holds the calendar time (seconds since the start of the Unix epoche), and a pointer to the <code>_tm</code> structure.

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

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

<source lang="C">int main(void)</source>
declares the main function, the first function that will be executed.

<source lang="C">u_long baud = 115200;</source>
Defines a variable of the type <code>u_long</code> (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. 

<source lang="C">
#ifdef RTC_CHIP
NutRegisterRtc(&RTC_CHIP);
#endif
</source>
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 ==

<source lang="c">
#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;
}

</source>

== Details ==

This example contains 3 additional functions: <code>EnterDate</code>, <code>EnterTime</code> and <code>SetLocalTime</code>

<source lang="C">
static int EnterDate(struct _tm *stm)
</source>
defines a function with a pointer to the <code>_tm</code> structure as parameter.
<source lang="C">
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);
</source>
The <code>scanf</code> statements store the user input in a local variable. Then the value gets stored in the <code>_tm</code> structure through the <code>stm</code> pointer.

<source lang="C">
static int EnterTime(struct _tm *stm)
</source>
behaves analog.

<source lang="C">
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);
}
}
</source>
defines a variable "ltm" of the structure type <code>_tm</code> and a variable "now" of type <code>time_t</code>.

<code>time(&now)</code> stores the current calender time in <code>now</code>.

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

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

== See also ==

* [[Caltime]]
* [[Time Zones]]
* [[RFC Date and Time Conversion]]
* More [[Nut/OS Examples]]

== External Links ==

[http://www.ethernut.de/en/hardware/enut3/x12x6.html X1226/X1286 Realtime Clock And Calendar] About the RTC chip on Ethernut 3.0.

[[Category:Code Snippets]]

{{Languages}}

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