CODEWITHSUNDEEP
embeddedarmmicrocontrollerreal-time-clock
Alex Xander
Alex Xander

Reputation: 4051

Coding realtime clock for for ARM architecture based microcontroller

I need to write a program to implement real time clock for ARM architecture. example: LPC213x

It should display Hour Minute and Seconds. I have no idea about ARM so having trouble getting started.

My code below is not working

// ...

int main (void) {
    int hour=0;
    int min=0;
    int sec;
    init_serial(); /* Init UART */
    Initialize();
    CCR=0x11;
    PCONP=0x1815BE; 
    ILR=0x1;         //  Clearing Interrupt

    //printf("\nTime is %02d:%02x:%02d",hour,min,sec);

    while (1) { /* Loop forever */
    }
}

void Initialize()
{
VPBDIV=0x0;
//CCR=0x2; 
//ILR=0x3; 
HOUR=0x0;
SEC=0x0;
MIN=0x0;


ILR = 0x03; 
CCR = (1<<4) | (1<<0); 

VICVectAddr13 = (unsigned)read_rtc; 
VICVectCntl13 |= 0x20 | VIC_RTC; 
VICIntEnable |= (1 << VIC_RTC);

}
/* Interrupt Service Routine*/
__irq void read_rtc() 
{
int hour=0;
int min=0;
int sec;
ILR=0x1;         //  Clearing Interrupt
hour=(CTIME0 & MASKHR)>>16;
min= (CTIME0 & MASKMIN)>>8;
sec=CTIME0 & MASKSEC;

printf("\nTime is %02d:%02x:%02d",hour,min,sec);

//VICVectAddr=0xff;
VICVectAddr = 0;
}

Upvotes: 2

Views: 5987

Answers (4)

Vishal Chovatiya
Vishal Chovatiya

Reputation: 99

A real-time clock (RTC) is a computer clock (most often in the form of an integrated circuit) that keeps track of the current time. Although the term often refers to the devices in personal computers, servers and embedded systems, RTCs are present in almost any electronic device which needs to keep accurate time.

You May refer this two link, i am sure it will give you further understanding :-

1). ARM Cortex Programming using CMSIS:- http://www.firmcodes.com/cmsis/

2). RTC Programming with ARM7:- http://www.firmcodes.com/microcontrollers/arm/real-time-clock-of-arm7-lpc2148/

Upvotes: 0

Jeff Lamb
Jeff Lamb

Reputation: 5865

This is all for the LPC2468. We have a setTime function too, but I don't want to do ALL the work for you. ;) We have custom register files for ease of access, but if you look at the LPC manual, it's obvious where they correlate. You just have to shift values into the right place, and do bitwise operations. For example:

#define RTC_HOUR       (*(volatile RTC_HOUR_t *)(RTC_BASE_ADDR + (uint32_t)0x28))

Time struture:

typedef struct {
  uint8_t  seconds;        /* Second value - [0,59] */
  uint8_t  minutes;        /* Minute value - [0,59] */
  uint8_t  hour;           /* Hour value - [0,23] */
  uint8_t  mDay;           /* Day of the month value - [1,31] */
  uint8_t  month;          /* Month value - [1,12] */
  uint16_t year;           /* Year value - [0,4095] */
  uint8_t  wDay;           /* Day of week value - [0,6] */
  uint16_t yDay;           /* Day of year value - [1,365] */
} rtcTime_t;

RTC functions:

void rtc_ClockStart(void) {
  /* Enable CLOCK into RTC */
  scb_ClockStart(M_RTC);
  RTC_CCR.B.CLKSRC = 1;
  RTC_CCR.B.CLKEN  = 1;
  return;
}

void rtc_ClockStop(void) {
  RTC_CCR.B.CLKEN = 0;
  /* Disable CLOCK into RTC */
  scb_ClockStop(M_RTC);
  return;
}

void rtc_GetTime(rtcTime_t *p_localTime) {
  /* Set RTC timer value */
  p_localTime->seconds = RTC_SEC.R;
  p_localTime->minutes = RTC_MIN.R;
  p_localTime->hour    = RTC_HOUR.R;
  p_localTime->mDay    = RTC_DOM.R;
  p_localTime->wDay    = RTC_DOW.R;
  p_localTime->yDay    = RTC_DOY.R;
  p_localTime->month   = RTC_MONTH.R;
  p_localTime->year    = RTC_YEAR.R;
}

System control block functions:

void scb_ClockStart(module_t module) {
  PCONP.R |= (uint32_t)1 << module;
}

void scb_ClockStop(module_t module) {
  PCONP.R &= ~((uint32_t)1 << module);
}

Upvotes: 1

Enjoy coding
Enjoy coding

Reputation: 4366

If you need information about ARM then this ARM System Developer's Guide: Designing and Optimizing System Software may help you.

We used to do some thing like this for ARM.

    #include "LPC21xx.h"
    void rtc()
    {
         *IODIR1 = 0x00FF0000;
             // Set LED ports to output
         *IOSET1 = 0x00020000;
         *PREINT = 0x000001C8;
            // Set RTC prescaler for 12.000Mhz Xtal
         *PREFRAC = 0x000061C0;
         *CCR = 0x01;
        *SEC = 0;
        *MIN = 0;
        *HOUR= 0;
    }

Upvotes: 1

unwind
unwind

Reputation: 399813

According to this board description for the LPC213x, it is delivered with an example program called "Real-Time Clock - Demonstrates how the real-time clock can be used". This also implies that the board features real-time clock hardware, which is going to make it a lot easier.

I suggest you read up on that program, to figure out how to talk to the RTC hardware. The next step would be to solve the display requirements. The two obvious choices are either 7-segment LED displays, or an LCD.

Both are well-known technologies about which loads have been written, follow the Wikipedia links to find out more.

Upvotes: 3

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