Fujitsu Microelectronics Europe
MCU-AN-390012-E-V11
Application Note
Processing DCF77-time signals
with the MB90670/5 series
using the ICU
© Fujitsu Microelectronics Europe GmbH, Microcontroller Application Group
History
18th Feb. 97
28th june 00
MM
TKa
V1.0
V1.1.
started
New format
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and must only be used in an evaluation laboratory environment.
1.
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full effect.
.
MCU-AN-390012-E-V11
-2-
© Fujitsu Microelectronics Europe GmbH
In many applications, exact time information is essential. Using a LF receiver for the German
time standard DCF77 can be a simple, but effective solution for this problem. But how to
decode the time-signal ? This application note shows how to connect a DCF77 receiver to a
MB90678 using the input capture function.
The 1978 law on time standards defines legal time in Europe on the basis of “Coordinated World
Time (UTC)” and gives the PTB (Physikalisch-technische Bundesanstalt, Germany) responsibility
for the keeping and broadcasting of legal time. Legal time in Europe is either Middle European Time
(Mitteleuropäische Zeit) : MEZ(D) = UTC(PTB) + 1h or Middle European Summer Time MESZ(D)
= UTC(PTB) + 2h and is generated in the PTB Atomic Clock in Braunschweig. It is transmitted from
a 50kW-transmitter in Mainflingen (near Frankfurt) on the frequency 77.5 kHz with a relative
deviation of the carrier (averaged over a day) of < 1-12 . The signal is transmitted in a 24-hour
continuous service. Short interruptions (of a few minutes) are possible because of servicing, when
switching to a backup transmitter or antenna. Thunderstorms can cause longer interruptions to the
service.
The carrier is amplitude-modulated with second marks. At the beginning of each second (with the
exception of the 59th second of each minute), the carrier amplitude is reduced to 25% for the
duration of either 100 or 200ms. The start of the carrier reduction marks the precise beginning of the
second. The minute is marked by the absence of the previous second mark. It is possible to achieve
accuracy better than 1ms at distances of several hundred kilometers around Frankfurt.
The transmission of the numerical values for minute, hour, day, weekday, month and year are BCDencoded through the pulse duration modulation of the second marks. A second mark with duration
0.1s encodes a binary 0 and a duration of 0.2s encodes 1. The order of encoding is shown in diagram
1. In the case of transmission of MEZ, mark 18 has a duration of 0.2s and mark 17 a duration of 0.1s.
If MESZ is being transmitted, this is reversed. Furthermore, an approaching transition from MEZ to
MESZ or back is announced by extending mark 16 from 0.1 to 0.2s for one hour prior to the
changeover.
Mark
number
0
1-14
15
16
17,18
19
20
21-27
28
29-34
35
36-41
42-44
45-49
50-57
58
Encodes
(0.1s = logic “0” ; 0.2s = logic “1”)
Minute, always 0
Reserved
0=Normal antenna, 1=backup antenna in use
1=Approaching change from MEZ to MESZ or back (1 hour before)
Time zone 0,1=MEZ; 1,0=MESZ
The leap second is encoded in this bit one hour prior to occurrence.
Start bit for encoded time, always 1
1, 2, 4, 8, 10, 20, 40 Minutes
P1 maintains even parity for marks 21-28
1,2,4,8,10,20 Hours
P2 maintains even parity for marks 29-35
Day in month (1, 2, 4, 8, 10, 20)
Day in week (1,2,4)
Month number (1, 2, 4, 8, 10)
Year (1, 2, 4, 8, 10, 20, 40, 80)
P3 maintains even parity for marks 36-58 There is no mark transmitted for the 59th second.
Diagram 1 : Encoding diagram
© Fujitsu Microelectronics Europe GmbH
-3-
MCU-AN-390012-E-V11
To obtain the code, any active antenna capable of receiving 77kHz and demodulating the signal can
be used. Such devices can be purchased by a number of electronic distributors in Europe. To feed the
signal into the microcontroller, the input capture unit (ICU) of the MB90670/5 series is purposebuild. This module detects rising or falling edges, measures timeslots and generates interrupts. The
maximum capture accuracy is 250 ns.
Diagram 2 shows the example application using a FZD01020 active antenna connected to the input
capture pin ASR1 of the MCU. The written demo software drives a dot matrix display connected to
port 6 (see last issue of spectrum!) to show the actual time and date. Additionally the MCU sends the
time-information via RS232 to a connected PC once the program is running. If the signal will not be
received anymore, an internal timer (16-bit timer0) will continue to count the seconds up until the
DCF77-signal is available again.
MCU-AN-390012-E-V11
-4-
© Fujitsu Microelectronics Europe GmbH
DCF77 Transmitter
Active Antenna
MB90675 MCU System
ICU
Diagram 2 : A simple time processing system using the MB90675
A system like this has many advantages compared to a normal quartz-based clock :
•
•
•
•
•
very accurate time (+/- 1 second in 1 Mio. years!)
can be a timebase for a whole computer network
automatic recognition of MEZ and MESZ
automatic recognition of leap years and minutes (!!!)
easy to program accurate alarms over month
The input capture unit can be set up easily and then works independently from the CPU, so that a
“decode-DFC77”-task can be run almost in the background of a main MCU-program. The
MB90670/75 series feature four input capture units, so other applications needing edge detecting can
be run simultaneously. For further information (democode etc.) please contact the MCU-group in
FMG.
© Fujitsu Microelectronics Europe GmbH
-5-
MCU-AN-390012-E-V11
/*
*********************************************************************
**
**
**
DFC77-CLOCK
**
**
**
**
for MB90678 (16bit-Starterkit)
**
**
can be run with Emulator
**
**
**
**
reads DFC77-Signal-Pulses via ICU1 (ASR1-Pin)
**
**
decodes the time signal and displays it on a LCD
**
**
connected to Port 6 (default-LCD-Type : LTN111)
**
**
(active antenna is FZD01020 by Channel Microelectronics
**
**
don't forget to add a pullup-restistor for signal-output
**
**
of antenna - it's an open-drain type)
**
**
**
**
Author : Markus Mierse
**
**
Version : 1 (backup timer for "no-signal"-case disabled)
**
**
Date
: 17.2.97
**
**
**
**
(C) Fujitsu Mikroelektronik GmbH 1997
**
**
**
*********************************************************************
*/
#include <sample\extn\mb90675.h>
/* for all Register Names */
/*----------------------- variables --------------------*/
typedef unsigned char BYTE;
/* BYTE definition */
int cursor;
/* display position */
int
int
int
int
i;
counter;
index;
begin;
/*
/*
/*
/*
int
int
int
int
int
int
min;
hr;
day;
dow;
month;
year;
/* update time and date variables */
int
int
int
int
int
int
int
sec;
minr;
hrr;
dayr;
dowr;
monthr;
yearr;
/* actual time and date */
long int puls;
long int dist;
long int t1;
/*--------------------void
void
void
void
general purpose integer variable */
counter for timer 0 */
index (0-58) of time protocol */
1 if begun to decode */
/* pulswidth of received signal */
/* distance from last puls */
/* pulsvariable */
prototypes --------------------*/
Init_Timer16(void);
Init_ICU(void);
decode(void);
Init_Timer24(void);
/*
/*
/*
/*
init timer routine */
init ICU */
decode-routine */
init 24-bit-timer routine */
__interrupt
void
Timer16(void);
/* ISR for timer0 */
__interrupt
void
Timer24of(void);
/* ISR for 24-bit timer overflow */
__interrupt
void
ICU1(void);
/* ISR for ICU1 */
void
void
void
void
void
void
void
void
initdisp(void);
/* display routines */
outb(unsigned char);
busy(void);
print(char *Name2);
printnum(int n);
printtime(int h,int m,int s);
printdate(int dw,int dr,int mr, int yr);
wait(int i);
MCU-AN-390012-E-V11
-6-
© Fujitsu Microelectronics Europe GmbH
/*---------------------------------------------------------------*/
/*
MAIN PROGRAM
*/
/*---------------------------------------------------------------*/
void main(void)
{
initdisp();
print("DFC77-TIMER");
/*
Init_Timer16();
/* setup display on port 6 */
/* show header */
/* init 16-bit timer 0 (disabled) */
Init_Timer24();
Init_ICU();
/* init 24-bit timer */
/* init ICU */
dist = 0;
begin = 0;
i = 0;
minr = 0;
hrr = 0;
sec = 0;
dayr = 0;
dowr = 0;
monthr = 0;
yearr = 0;
/* init variables */
#pragma asm
MOV
ILM, #7
OR
CCR, #H'40
#pragma endasm
while(1);
; allow all interrupts with level<7
; enable interrupts
/* dummy loop (wait for interrupt) */
}
/*---------------------- function bodies ----------------------*/
/*---------------------------------------------------------------*/
/* Initial Routine for ICU : This routine sets the ICU0 as input */
/*---------------------------------------------------------------*/
void Init_ICU(void)
{
ICR07 = 6;
}
/* INT level 6 for ICU interrupt */
ICC_IRE0
ICC_IRE1
ICC_IRE2
ICC_IRE3
=
=
=
=
0;
1;
0;
0;
/* 1=Interrupt enable for ICU#0..3 */
ICC_IR0
ICC_IR1
ICC_IR2
ICC_IR3
=
=
=
=
0;
0;
0;
0;
/* Interrupt request (set to 0) */
ICC_EG0
ICC_EG1
ICC_EG2
ICC_EG3
=
=
=
=
0;
1;
0;
0;
/* detect : 0=no edges, 1=rising edges */
/*
2=falling or 3=both edges */
© Fujitsu Microelectronics Europe GmbH
-7-
MCU-AN-390012-E-V11
/*---------------------------------------------------------------*/
/* Interrupt Service Routine : Input capture unit 1 (Pin P65)
*/
/*---------------------------------------------------------------*/
__interrupt
void
ICU1(void)
{
ICC_IR1 = 0;
/* clear interrupt request */
if (ICC_EG1 == 1)
/* If rising edge was detected */
{
dist = ((ICR1 - t1) / 10000);
/* measure distance from last puls */
ICC_EG1 = 2;
/* detect falling edge now */
TCCR_CLR = 0;
/* reset 24-bit-timer */
}
else
/* If falling edge was detected */
{
t1 = ICR1;
puls = (t1 / 1000);
/* puls : 400..500=100ms ; 800..900=200ms */
if ((puls > 400) && (puls < 500))
/* 0 received (100ms) */
{
if (dist < 700)
/* within normal protocol ? */
{
sec++;
/* next second */
if ((sec == 10) || (sec == 20) || (sec == 30) || (sec == 40) || (sec == 50))
printdate(dowr,dayr,monthr,yearr); /* show date every 10 seconds */
else
printtime(hrr,minr,sec);
/* show time */
if (begin == 1)
/* if tracing protocol */
{
index++;
/* increase mark */
if (index == 58)
/* protocol finished ? */
{
hrr = hr;
/* update time & date */
minr = min;
dayr = day;
dowr = dow;
monthr = month;
yearr = year;
}
}
}
else
/* begin of protocol and new minute */
{
begin = 1;
index = 0;
sec = 0;
hr = 0;
min = 0;
day = 0;
dow = 0;
month = 0;
year = 0;
}
}
if ((puls > 800) && (puls < 900))
/* 1 received */
{
if (dist < 700)
/* within normal protocol ? */
{
sec++;
/* next second */
if ((sec == 10) || (sec == 20) || (sec == 30) || (sec == 40) || (sec == 50))
printdate(dowr,dayr,monthr,yearr); /* show date every 10 seconds */
else
printtime(hrr,minr,sec);
/* show time */
if (begin == 1)
/* tracing marks ? */
{
index++;
/* increase mark */
decode();
/* decode protocol */
if (index == 58)
/* protocol finished ? */
{
hrr = hr;
/* update time & date */
minr = min;
dayr = day;
dowr = dow;
monthr = month;
yearr = year;
}
}
}
else
{
begin = 0;
/* WRONG ! Do not begin to decode */
sec = 0;
}
}
ICC_EG1 = 1;
/* detect raising edge again */
}
}
MCU-AN-390012-E-V11
-8-
© Fujitsu Microelectronics Europe GmbH
/*---------------------------------------------------------------*/
/* Decode : This procedure decodes the puls-code into time & date*/
/* currently no parity-check (marks 28,35,58), no additional
*/
/* information (backup antenna, time zone etc)
*/
/*---------------------------------------------------------------*/
void decode(void)
{
switch(index)
{
case 21: {min++; break;}
case 22: {min = min + 2; break;}
case 23: {min = min + 4; break;}
case 24: {min = min + 8; break;}
case 25: {min = min + 10; break;}
case 26: {min = min + 20; break;}
case 27: {min = min + 40; break;}
case 29: {hr++; break;}
case 30: {hr = hr + 2; break;}
case 31: {hr = hr + 4; break;}
case 32: {hr = hr + 8; break;}
case 33: {hr = hr + 10; break;}
case 34: {hr = hr + 40; break;}
case 36: {day++; break;}
case 37: {day = day + 2; break;}
case 38: {day = day + 4; break;}
case 39: {day = day + 8; break;}
case 40: {day = day + 10; break;}
case 41: {day = day + 20; break;}
case 42: {dow++; break;}
case 43: {dow = dow + 2; break;}
case 44: {dow = dow + 4; break;}
case 45: {month++; break;}
case 46: {month = month + 2; break;}
case 47: {month = month + 4; break;}
case 48: {month = month + 8; break;}
case 49: {month = month + 10; break;}
case 50: {year++; break;}
case 51: {year = year + 2; break;}
case 52: {year = year + 4; break;}
case 53: {year = year + 8; break;}
case 54: {year = year + 10; break;}
case 55: {year = year + 20; break;}
case 56: {year = year + 40; break;}
case 57: {year = year + 80; break;}
}
}
/* index=second marks on "1" */
/* 21-27 minutes */
/* 29-34 hours */
/* 36-41 day in month */
/* 42-44 day in week */
/* 45-49 month */
/* 50-57 year */
/*---------------------------------------------------------------*/
void Init_Timer24(void)
/* init free run timer */
{
ICR06 = 6;
/* INT level 6 */
/*
}
TCCR_STP = 0;
/* stop timer */
TCCR_CLR = 0;
TCCR_PR0 = 0;
TCCR_IVF = 0;
TCCR_IVFE = 1;
TCCR_TIM = 0;
TCCR_TIME = 0;
TCCR_TIS1 = 0;
TCCR_TIS0 = 1;
/*
/*
/*
/*
/*
/*
/*
TCCR_STP = 1;
/* start timer (disabled) */
0=clear timer */
0=select clock : PLL/4 */
0=clear interrupt request */
1=enable overflow INT */
0=clear interrupt request */
1=enable bit interm. INT */
01=set bit period to 1024us */
/*---------------------------------------------------------------*/
/* Interrupt Service Routine : 24-bit timer overflow
*/
/* occurs every 4.1 seconds
*/
/* currently only used to indicate that no signal is available
*/
/*---------------------------------------------------------------*/
__interrupt
void
Timer24of(void)
{
TCCR_IVF = 0;
print("NO DFC-SIGNAL...");
/* clear int request */
/* occurs every 4.194 seconds */
/* show error massage */
}
/*---------------------------------------------------------------*/
/* Initial Routine for 16-bit timer0 : This routine sets the
*/
© Fujitsu Microelectronics Europe GmbH
-9-
MCU-AN-390012-E-V11
/* control register bits for reload-timer use and writes the
*/
/* appropriate value to the reload-register dep. on clock speed */
/*---------------------------------------------------------------*/
void Init_Timer16(void)
{
ICR09 = 6;
/* INT level 6 for timer interrupt */
TMCSR0_CSL1 = 1;
TMCSR0_CSL0 = 0;
TMCSR0_MOD2 = 0;
TMCSR0_MOD1 = 0;
TMCSR0_MOD0 = 0;
TMCSR0_OUTE = 0;
TMCSR0_OUTL = 0;
TMCSR0_RELD = 1;
TMCSR0_INTE = 1;
TMCSR0_UF
= 0;
TMCSR0_CNTE = 1;
/* Clock : 00 = PLL/2 (with 16MHz = 0.125us) */
/* 01 = PLL/8 (0.5us) ; 10 = PLL/32 (2us) */
/* 000 = Input trigger pin disabled */
TMRLR0 = 50000;
/* Reload-value for 16 MHz-clock source */
TMCSR0_TRG = 1;
/* Trigger : ...Go ! */
/*
/*
/*
/*
/*
/*
0
0
1
1
0
1
=
=
=
=
=
=
TOUT-pin disabled */
TOUT-pin output level */
reload timer; 0 = one shot timer */
Interrupt enable */
Underflow Interrupt disable */
timer enable - wait for trigger */
}
/*---------------------------------------------------------------*/
/* Interrupt Service Routine : 16-bit timer 0
*/
/* occurs every second - counts seconds up when no signal is
*/
/* available. Currently disabled...
*/
/*---------------------------------------------------------------*/
__interrupt
void Timer16(void)
{
TMCSR0_UF = 0;
counter++;
if (counter == 10)
{
if (begin == 0) {sec++;};
if (sec == 60)
{
sec = 0;
minr++;
if (minr == 60)
{
minr = 0;
hrr++;
if (hrr == 24)
{
hrr = 0;
}
}
}
/* clear int request */
/* 10 * 100msec = 1s */
/* increase second only if no signal */
/* check beginning of new min,hour */
/* every 10 seconds display date for one second */
}
}
if ((sec == 10) || (sec ==20) || (sec == 30) || (sec == 40) || (sec == 50))
{
printdate(dowr,dayr,monthr,yearr);
}
else
{
printtime(hrr,minr,sec);
}
counter = 0;
MCU-AN-390012-E-V11
- 10 -
© Fujitsu Microelectronics Europe GmbH
/*---------------------------------------------------------------*/
/* Display routines (Display LTN111 connected to port 6)
*/
/*---------------------------------------------------------------*/
void initdisp(void)
{
}
/* This Routine initializes the LCD on port6 */
DDR6=0x0DF;
PDR6=0;
/* Port 6 Output except P65 (ICU1 !) */
/* Port 6 Off*/
PDR6=0x013;
PDR6=0x03;
wait(1000);
PDR6=0x013;
PDR6=0x03;
wait(1000);
PDR6=0x013;
PDR6=0x03;
wait(1000);
PDR6=0x012;
PDR6=0x02;
/* Startup sequence */
outb(0x028);
outb(0x0C);
outb(0x06);
outb(0x03);
outb(0x01);
/*
/*
/*
/*
/*
void outb(unsigned char a)
{
BYTE b;
cursor++;
if (cursor == 9)
{
PDR6=0x01C;
PDR6=0x00C;
PDR6=0x010;
PDR6=0;
busy();
}
b=(a & 0x0F0);
b = b >> 4;
if (a & 0x080) {b=(b
b=(b & 135);
b=(b | 16);
PDR6=b;
b=(b & 135);
PDR6=b;
b=(a & 143);
b=(b | 16);
PDR6=b;
b=(b & 143);
PDR6=b;
busy();
Switch to 4-bit mode */
Cursor Off (on=0x0F) */
No shift */
Cursor home */
Display clear */
/* send one byte to the display */
/* correct position !LNT111-R only!*/
/* shift upper nibble */
/* to lower nibble */
| 0x080);};
/* but keep Bit 7 */
/* set other bits to zero
/* set E line */
/* send to LCD */
/* clear E line */
/* send to LCD */
/* take lower nibble */
/* set E line */
/* send to LCD */
/* clear E line */
/* send to LCD */
/* wait for busy-line */
*/
}
void busy(void)
{
BYTE b;
PDR6=0;
b=1;
while (b)
{
DDR6=0x0D0;
PDR6=0x05F;
b=PDR6_PD63;
PDR6_PD64 = 0;
PDR6_PD64 = 1;
PDR6_PD64 = 0;
PDR6_PD66 = 0;
DDR6=0x0DF;
}
}
void print(char *Name2)
/* This Routine polls the busy-line */
/* Port 3 Off before reading ! */
/* wait for Busy-line */
/* set Bus as input to read Bit .3 (Busy) */
/* busy request */
/* read Port */
/* toggle E */
/* reset Port to output */
/* This Routine displays a String */
© Fujitsu Microelectronics Europe GmbH
- 11 -
MCU-AN-390012-E-V11
{
unsigned char c;
BYTE b;
int i,l;
outb(1);
l=strlen(Name2);
cursor=0;
for (i=0; i<l; i++)
{
c=(Name2[i]);
b=(c | 128);
outb(b);
}
}
/* Display clear */
/* go through string */
/* pick char */
/* and display it */
void printnum(int n)
/* show integer value on LCD display */
{
float x;
int l;
if (n < 10)
/* only one digit value */
{
outb(0x0b0);
outb(0x0b0);
outb((n+48) | 128);
}
else if (n >= 10 && n<100) /* two digit value */
{
outb(0x0b0);
outb(((n/10)+48) | 128);
x = n-(10*(n / 10));
l = x;
outb((l+48) | 128);
}
else if (n >= 100)
/* show three digits */
{
outb(((n/100)+48) | 128);
x = n-(100*(n / 100));
n = x;
outb(((n/10)+48) | 128);
x = n-(10*(n / 10));
l = x;
outb((l+48) | 128);
}
}
void printdate(int dw,int dr,int mr, int yr) /* show date on LCD display
{
float x;
int l;
outb(1);
/* Display clear */
switch(dw)
{
case 1:{outb(77
case 2:{outb(84
case 3:{outb(87
case 4:{outb(84
case 5:{outb(70
case 6:{outb(83
case 7:{outb(83
}
outb(32 | 128);
/* display day of week */
|
|
|
|
|
|
|
128);
128);
128);
128);
128);
128);
128);
outb(79
outb(85
outb(69
outb(72
outb(82
outb(65
outb(85
if (dr < 10)
{
outb(0x0b0);
outb((dr+48) | 128);
}
else if (dr >= 10 && dr<100)
{
outb(((dr/10)+48) | 128);
x = dr-(10*(dr / 10));
l = x;
outb((l+48) | 128);
}
|
|
|
|
|
|
|
128);
128);
128);
128);
128);
128);
128);
break;}
break;}
break;}
break;}
break;}
break;}
break;}
/*
/*
/*
/*
/*
/*
/*
MO
TU
WE
TH
FR
SA
SU
*/
*/
*/
*/
*/
*/
*/
*/
/* day in month : only one digit value */
/* two digit value */
outb(46 | 128);
if (mr < 10)
{
outb(0x0b0);
MCU-AN-390012-E-V11
/* month : only one digit value */
- 12 -
© Fujitsu Microelectronics Europe GmbH
outb((mr+48) | 128);
}
else if (mr >= 10 && mr<100)
{
outb(((mr/10)+48) | 128);
x = mr-(10*(mr / 10));
l = x;
outb((l+48) | 128);
}
/* two digit value */
outb(46 | 128);
}
if (yr < 10)
{
outb(0x0b0);
outb((yr+48) | 128);
}
else if (yr >= 10 && yr<100)
{
outb(((yr/10)+48) | 128);
x = yr-(10*(yr / 10));
l = x;
outb((l+48) | 128);
}
void printtime(int h,int m,int s)
{
float x;
int l;
outb(1);
if (h < 10)
{
outb(0x0b0);
outb((h+48) | 128);
}
else if (h >= 10 && h<100)
{
outb(((h/10)+48) | 128);
x = h-(10*(h / 10));
l = x;
outb((l+48) | 128);
}
/* year : only one digit value */
/* two digit value */
/* show time on LCD display hh:mm:ss */
/* Display clear */
/* hours : only one digit value */
/* two digit value */
outb(58 | 128);
if (m < 10)
{
outb(0x0b0);
outb((m+48) | 128);
}
else if (m >= 10 && m<100)
{
outb(((m/10)+48) | 128);
x = m-(10*(m / 10));
l = x;
outb((l+48) | 128);
}
/* minutes : only one digit value */
/* two digit value */
outb(58 | 128);
}
if (s < 10)
{
outb(0x0b0);
outb((s+48) | 128);
}
else if (s >= 10 && s<100)
{
outb(((s/10)+48) | 128);
x = s-(10*(s / 10));
l = x;
outb((l+48) | 128);
}
/* seconds : only one digit value */
/* two digit value */
/*---------------------------------------------------------------*/
void wait(int i)
{
for (; i ; i--);
/* very simple delay loop */
}
/*---------------------------------------------------------------*/
© Fujitsu Microelectronics Europe GmbH
- 13 -
MCU-AN-390012-E-V11