32.768kHz oscillator is not oscillating,

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hussain1.bangalore

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Hi



I have designed lpc 1768 board , all the devices connected to it is working well except RTC,,, i think oscillator is not working,,,

things is cross checked and replaced is

capacitor from 10pf to 39 pf
oscillator
and connected 1 megh ohm resistor across the oscillator


all these things have performed even though oscillator is not oscillating ,i have checked all recent threads & forums and followed the procedure even though no fruitfulll


please Help




thanks
 

There are several reported problems and complaints concerning the LPC1768's RTC, including:




Let you know if I come across any more info.
 

ok,, thanks for your concern i am desperately waiting for u reply



regards

hussain
 

Here are some troubleshooting tips:


Here is some code correctly initializing the RTC from NXP:

Code: 
int main(void)
{
 RTCInit();
 RTCStart();
 NVIC_EnableIRQ( RTC_IRQn) ;
}

/*********** ********* ********* ********* ********* ********* ********* ********* ***
 *   rtc.c:  Realtime clock C file for NXP LPC17xx Family Microprocessors
 *
 *   Copyright(C) 2009, NXP Semiconductor
 *   All rights reserved.
 *
 *   History
 *   2009.05.26  ver 1.00    Prelimnary version, first Release
 *
************ ********* ********* ********* ********* ********* ********* ********* **/

/*********** ********* ********* ********* ********* ********* ********* ********* ********* *******
 Includes
************ ********* ********* ********* ********* ********* ********* ********* ********* ******/
#include "lpc17xx.h"
#include "type.h"
#include "stdio.h"
#include "rtc.h"


RTCTime relogio_atual;

/*********** ********* ********* ********* ********* ********* ********* ********* ***
** Function name:  RTC_IRQHandler
**
** Descriptions:  RTC interrupt handler
**
** parameters:   None
** Returned value:  None
**
************ ********* ********* ********* ********* ********* ********* ********* **/
void RTC_IRQHandler (void)
{
 LPC_RTC->ILR |= ILR_RTCCIF; //reset pending int flag 
 relogio_atual = RTCGetTime() ; //read RTC;
}

/*********** ********* ********* ********* ********* ********* ********* ********* ***
** Function name:  RTCInit
**
** Descriptions:  Initialize RTC timer
**
** parameters:   None
** Returned value:  None
** 
************ ********* ********* ********* ********* ********* ********* ********* **/
void RTCInit( void )
{
  // Enable CLOCK into RTC
  LPC_SC->PCONP |= (1 << 9);

  //If RTC is stopped, clear STOP bit.
  if ( LPC_RTC->RTC_AUX & (0x1<<4) )
  {
 LPC_RTC->RTC_AUX |= (0x1<<4);
  }

  //--- Initialize registers ---
  LPC_RTC->AMR = 0;
  LPC_RTC->CIIR = 1; //INT every 1 sec;
  LPC_RTC->CCR = 0;
  return;
}

/*********** ********* ********* ********* ********* ********* ********* ********* ***
** Function name:  RTCStart
**
** Descriptions:  Start RTC timer
**
** parameters:   None
** Returned value:  None
** 
************ ********* ********* ********* ********* ********* ********* ********* **/
void RTCStart( void ) 
{
 /*--- Start RTC counters ---*/
 LPC_RTC->CCR |= CCR_CLKEN;
 LPC_RTC->ILR = ILR_RTCCIF;
}

/*********** ********* ********* ********* ********* ********* ********* ********* ***
** Function name:  RTCStop
**
** Descriptions:  Stop RTC timer
**
** parameters:   None
** Returned value:  None
** 
************ ********* ********* ********* ********* ********* ********* ********* **/
void RTCStop( void )
{   
 /*--- Stop RTC counters ---*/
 LPC_RTC->CCR &= ~CCR_CLKEN;
} 

/*********** ********* ********* ********* ********* ********* ********* ********* ***
** Function name:  RTC_CTCReset
**
** Descriptions:  Reset RTC clock tick counter
**
** parameters:   None
** Returned value:  None
** 
************ ********* ********* ********* ********* ********* ********* ********* **/
void RTC_CTCReset( void )
{   
 LPC_RTC->CCR |= CCR_CTCRST;
}

/*********** ********* ********* ********* ********* ********* ********* ********* ***
** Function name:  RTCSetTime
**
** Descriptions:  Setup RTC timer value
**
** parameters:   None
** Returned value:  None
** 
************ ********* ********* ********* ********* ********* ********* ********* **/
void RTCSetTime( RTCTime Time ) 
{
 LPC_RTC->SEC = Time.RTC_Sec;
 LPC_RTC->MIN = Time.RTC_Min;
 LPC_RTC->HOUR = Time.RTC_Hour;
 LPC_RTC->DOM = Time.RTC_Mday;
 LPC_RTC->DOW = Time.RTC_Wday;
 LPC_RTC->DOY = Time.RTC_Yday;
 LPC_RTC->MONTH = Time.RTC_Mon;
 LPC_RTC->YEAR = Time.RTC_Year;    
}

/*********** ********* ********* ********* ********* ********* ********* ********* ***
** Function name:  RTCSetAlarm
**
** Descriptions:  Initialize RTC timer
**
** parameters:   None
** Returned value:  None
** 
************ ********* ********* ********* ********* ********* ********* ********* **/
void RTCSetAlarm( RTCTime Alarm ) 
{   
 LPC_RTC->ALSEC = Alarm.RTC_Sec;
 LPC_RTC->ALMIN = Alarm.RTC_Min;
 LPC_RTC->ALHOUR = Alarm.RTC_Hour;
 LPC_RTC->ALDOM = Alarm.RTC_Mday;
 LPC_RTC->ALDOW = Alarm.RTC_Wday;
 LPC_RTC->ALDOY = Alarm.RTC_Yday;
 LPC_RTC->ALMON = Alarm.RTC_Mon;
 LPC_RTC->ALYEAR = Alarm.RTC_Year;    
}

/*********** ********* ********* ********* ********* ********* ********* ********* ***
** Function name:  RTCGetTime
**
** Descriptions:  Get RTC timer value
**
** parameters:   None
** Returned value:  The data structure of the RTC time table
** 
************ ********* ********* ********* ********* ********* ********* ********* **/
RTCTime RTCGetTime( void ) 
{
 RTCTime LocalTime;
 
 LocalTime.RTC_ Sec = LPC_RTC->SEC;
 LocalTime.RTC_ Min = LPC_RTC->MIN;
 LocalTime.RTC_ Hour = LPC_RTC->HOUR;
 LocalTime.RTC_ Mday = LPC_RTC->DOM;
 LocalTime.RTC_ Wday = LPC_RTC->DOW;
 LocalTime.RTC_ Yday = LPC_RTC->DOY;
 LocalTime.RTC_ Mon = LPC_RTC->MONTH;
 LocalTime.RTC_ Year = LPC_RTC->YEAR;
 return ( LocalTime );    
}

/*********** ********* ********* ********* ********* ********* ********* ********* ***
** Function name:  RTCSetAlarmMask
**
** Descriptions:  Set RTC timer alarm mask
**
** parameters:   Alarm mask setting
** Returned value:  None
** 
************ ********* ********* ********* ********* ********* ********* ********* **/
void RTCSetAlarmMask( uint32_t AlarmMask ) 
{
 /*--- Set alarm mask ---*/    
 LPC_RTC->AMR = AlarmMask;
}

/*********** ********* ********* ********* ********* ********* ********* ********* ***
**                            End Of File
************ ********* ********* ********* ********* ********* ********* ********* ***/


/*********** ********* ********* ********* ********* ********* ********* ********* ***
 *   rtc.h:  Header file for NXP LPC17xx Family Microprocessors
 *
 *   Copyright(C) 2009, NXP Semiconductor
 *   All rights reserved.
 *
 *   History
 *   2009.05.27  ver 1.00    Prelimnary version, first Release
 *
************ ********* ********* ********* ********* ********* ********* ********* ***/

typedef struct {
    uint32_t RTC_Sec;     /* Second value - [0,59] */
    uint32_t RTC_Min;     /* Minute value - [0,59] */
    uint32_t RTC_Hour;    /* Hour value - [0,23] */
    uint32_t RTC_Mday;    /* Day of the month value - [1,31] */
    uint32_t RTC_Mon;     /* Month value - [1,12] */
    uint32_t RTC_Year;    /* Year value - [0,4095] */
    uint32_t RTC_Wday;    /* Day of week value - [0,6] */
    uint32_t RTC_Yday;    /* Day of year value - [1,365] */
} RTCTime;

#define IMSEC  0x00000001
#define IMMIN  0x00000002
#define IMHOUR  0x00000004
#define IMDOM  0x00000008
#define IMDOW  0x00000010
#define IMDOY  0x00000020
#define IMMON  0x00000040
#define IMYEAR  0x00000080

#define AMRSEC  0x00000001  /* Alarm mask for Seconds */
#define AMRMIN  0x00000002  /* Alarm mask for Minutes */
#define AMRHOUR  0x00000004  /* Alarm mask for Hours */
#define AMRDOM  0x00000008  /* Alarm mask for Day of Month */
#define AMRDOW  0x00000010  /* Alarm mask for Day of Week */
#define AMRDOY  0x00000020  /* Alarm mask for Day of Year */
#define AMRMON  0x00000040  /* Alarm mask for Month */
#define AMRYEAR  0x00000080  /* Alarm mask for Year */

#define PREINT_RTC 0x000001C8  /* Prescaler value, integer portion, 
        PCLK = 15Mhz */
#define PREFRAC_RTC 0x000061C0  /* Prescaler value, fraction portion, 
        PCLK = 15Mhz */

#define ILR_RTCCIF 0x01
#define ILR_RTCALF 0x02

#define CCR_CLKEN 0x01
#define CCR_CTCRST 0x02
#define CCR_CLKSRC 0x10


#define IDEAL_RTC_FREQ  32768000 //in mHz (milli Hz)
#define MAX_DELTA_FREQUENCY _VALUE (IDEAL_RTC_FREQ / ((1 << CALIBRATION_ VALUE_SIZE) - 1))
#define CALIBRATION_ VALUE_SIZE 17
#define CALDIR(n) (n << 17) //1 = Backward, 0 = Forward
#define CCALEN (1<<4)


void RTC_IRQHandler (void);
void RTCInit( void );
void RTCStart( void );
void RTCStop( void );
void RTC_CTCReset( void );
void RTCSetTime( RTCTime );
RTCTime RTCGetTime( void );
void RTCSetAlarm( RTCTime );
void RTCSetAlarmMask( uint32_t AlarmMask );

/*********** ********* ********* ********* ********* ********* ********* ********* ***
**                            End Of File
************ ********* ********* ********* ********* ********* ********* ********* ***/

Hope this helps in your endeavor.
 
Got the attached diagram from the datasheet

It shows you should connect the 32.768KHz crystal externally, if the crystal you have connected has failed try replacing it by the new one

Have you connected a battery to the Vbat pin of the controller

just for your reference
1.The RTC typically fails when Vi(VBAT) drops below 1.6 V.
2.When the RTC is not used, connect VBAT to VDD(REG)(3V3) and leave RTCX1 floating - make sure you notice this in the circuit.

Hope it works soon
 

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I will follow your steps and get back too u soon,, thanks a lot



hussain

---------- Post added at 07:57 ---------- Previous post was at 07:55 ----------





I will follow your steps and get back too u soon,, thanks a lot



hussain

---------- Post added at 08:01 ---------- Previous post was at 07:57 ----------

hi sunil
thanks for u r reply


I have have one proto type board which is working,, but i ordered same boards of 100 no.s they r not working i tried with all the thing s which u have posted previously
 

The reports I've read indicate the problem is very batch oriented. Some of the mbeds, which are LPC1768 based, had several problems including the RTC, while other units worked fine. I'll still keep an eye out for other workarounds or tips.
 

Hi the output of the oscillator pins is 0.7v and 0.01v and i don't think the output is correct
 

ckshivaram said:
it should be around 0.9 and 0.7v ............

is there any capacitors for the crystal???
Click to expand...

ya sir capacitor value of 22pf i have used across the terminals of oscillator even though i m lacking of output

---------- Post added at 08:44 ---------- Previous post was at 08:42 ----------
bigdogguru said:
The reports I've read indicate the problem is very batch oriented. Some of the mbeds, which are LPC1768 based, had several problems including the RTC, while other units worked fine. I'll still keep an eye out for other workarounds or tips.
Click to expand...

ya still i m trying all the tricks
 

what happens if you dont use any capacitors... even then it should work..... did you try replacing the crystal oscillator..... can you measure the frequency at those point using a multimeter or oscilloscope.....
 

ckshivaram said:
what happens if you dont use any capacitors... even then it should work..... did you try replacing the crystal oscillator..... can you measure the frequency at those point using a multimeter or oscilloscope.....
Click to expand...

i ll check it and come back to you sir



thanks

hussain

---------- Post added at 08:47 ---------- Previous post was at 08:46 ----------

i have changed the oscillator also but no use sir
 

You know things are bad when NXP's Errata sheet states:

Problem:
The RTC does not work reliably within the temperature specification.
Work-around:
None.
Click to expand...

NXP announced that sometime this year they should have the problem solved with a new die. Of course this doesn't help all the people who have already purchased units of the previous design.
 

bigdogguru said:
You know things are bad when NXP's Errata sheet states:



NXP announced that sometime this year they should have the problem solved with a new die. Of course this doesn't help all the people who have already purchased units of the previous design.
Click to expand...


I have have one proto type board which is working,, but i ordered same boards of 100 no.s they r not working i tried with all the thing s which u have posted previously

but Ic s are off same packing
 

What is the exact date and lot or batch code on the LPC1768 chip? I know someone else who experienced a the same problem. I believe he has a sheet with defective lots, I have him check it for you.
 

bigdogguru said:
What is the exact date and lot or batch code on the LPC1768 chip? I know someone else who experienced a the same problem. I believe he has a sheet with defective lots, I have him check it for you.
Click to expand...

serial no which is on LPC 1768

SR6975.1 08
ZSD1044-

plz check it


thanks & regards
hussain

---------- Post added at 04:51 ---------- Previous post was at 04:50 ----------
ckshivaram said:
did you check oscillations on thise pins??/

---------- Post added at 17:18 ---------- Previous post was at 16:53 ----------
Click to expand...



ya sir i have gone through the voltages are 0.7 and 0.01 at terminals of oscillator
 

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