LGOTO    INIT

158A   BSF    PCLATH,3
120A   BCF    PCLATH,4
2BFE   GOTO   h'3FE'

   LCALL   GET_TBL_DATA

118A   BCF    PCLATH,3
120A   BCF    PCLATH,4
20ED   CALL   h'ED"

setpch  macro
        if      ($ >= 0) && ($ < 0x800)
        bcf     PCLATH,3
        else
        bsf     PCLATH,3
        endif
        endm

03433 ;####################################################################
03434 ;
03435 ;                          Initial routine
03436 ;
03437 ;####################################################################

Register Initial value Description PORTA PORTB PORTC 00000000 The contents of each port register are cleared. RCSTA 10010000 A serial port is used. Continuing reception is set. ADCON0 00000000 A/D conversion function isn't used. ADCON1 00000110 All ports are used as the digital port. TRISA 00010000 RA4 is set as input mode. Others are set as output mode. TRISB 00001100 RB2, RB3 are set as input mode. Others are set as output mode. TRISC 11000000 RC6, RC7 are set as input mode. Others are set as output mode. OPTION_REG 00000000 Inner pull up isn't used. Internal clock is used. Prescaler is used for the TMR0 timer. Prescaler value is 1:2. SPBRG 01010010 9,600 bps is specified. ( Value is 82 ) TXSTA 00100110 8 bits communication. Transmit enable. Asynchronous mode. High speed. "1" is set to the TRMT bit. But it's unnecessary because it's read only. T2CON 00000110 Postscaler of timer 2 is 1:1. Timer 2 is used. Prescaler is 1:16. TMR2 00000000 The value of timer 2 is cleared. PR2 00010011 Timer 2 period is set. Set value is count value (20) - 1. (1/12.8MHz)*(4cycle/clock)*(20count(PR2))*(16(Prescaler)) 0,078125uS*4*20*16=100uS PIE1 00100010 USART receive interrupt is used. TMR2 to PR2 match interrupt is used. INTCON 11000000 Enables all un-masked interrupts. Enables all un-masked peripheral interrupts

Initialization of various work areas
Initialization of time area
Time display mode reading from EEPROM
Initialization of a liquid crystal display

03536 ;####################################################################
03537 ;
03538 ;                           Main routine
03539 ;
03540 ;####################################################################

Initial message display Software flow chart (1/11)
	Initial message is displayed for 2 seconds immediately after the turning on.
Update of the time display Software flow chart (1/11)
	A time stamp is updated every second by "clock_main" subroutine. The calling of a subroutine is cyclically done irrespective of 1 second. Update timing in 1 second is judged in the subroutine. The reason for making a subroutine is to update a time stamp while time setting is done. In case of keying-in wait, "clock_main" is always called and a time stamp update is done.
Processing of a time setting key Software flow chart (2/11), Software flow chart (3/11)
	This processing is processing with most steps in a main routine. At first, whether or not a menu key was pushed is checked. The key which should be pushed first is a menu key and the other key push is invalid. In the waiting time of the key operation, it is set to 10 seconds. If 10 seconds pass since the last key operation, the key operation till then will become invalid. 03672 CALL DISP_MAIN ;Time display Above-mentioned processing is the subroutine calling which is written in the lower right of Software flow chart (1/11). You can think that there is no necessity since "disp_main" subroutine is used also in "clock_main" subroutine. However, "clock_main" subroutine updates a display only every second. Therefore, when escaping from key processing, it is necessary to call "disp_main" subroutine, and it is necessary to display time immediately. At the time of key operation, the message of key operation is displayed on the display, and time is not displayed. "Time stamp mode changing" or "Setting of a timer" is performed by the key to operate after the first menu key.
"clock_main" subroutine Software flow chart (4/11)
	The display timing of a display and the timing of decoding are judged in this subroutine. A display is updated by "disp_main" subroutine every 0 second. Moreover, "dec_time" subroutine is executed for every 400 miliseconds. In this subroutine, processing which analyzes the information put on the electric wave and is changed into time information is performed.
"disp_main" subroutine Software flow chart (5/11)
	In this subroutine, processing which displays time or a message on LCD is performed.

03973 ;####################################################################
03974 ;
03975 ;                      Interruption processing
03976 ;
03977 ;####################################################################

03979         BTFSC   PIR1,TMR2IF     ;timer2(100uS) int ?
03980         GOTO    TIMER_INT       ;Yes.
03981         BTFSC   PIR1,RCIF       ;RX int ?
03982         GOTO    SIO_INT         ;Yes.
              GOTO    INT_VEC1        ;No. Jump to return

By interruption processing for 100 microseconds, the following processings are executed.

* Subtraction of a 100uS counter ( Every 100uS ) Software flow chart (6/11)

In this software, LCD etc. are controlled per 100uS. ( delay 100u subroutine )
In order to make this time, the counter value is subtracted by interruption processing of 100uS.


* Subtraction of a 10mS counter ( Every 10mS ) Software flow chart (6/11)

Time is measured to 10mS based on 100uS interruption, and the counter of 10mS is subtracted.


* LED lighting time control ( Every 10mS ) Software flow chart (6/11)

The signal of true second, true minute, true hour, true day and true month are outputted only 100mS.


* Information analysis of TCO(Time Code Output) ( Every 10mS ) Software flow chart (7/11), Software flow chart (8/11)

There are three kinds of signals of TCO. They are operating by the following standards and judging standards.



Kind	Standard	Criterion in processing
Marker	200mS ± 5mS	80mS to 280mS
"1" signal	500mS ± 5mS	400mS to 600mS
"0" signal	800mS ± 5mS	700mS to 880mS



As for a TCO signal, the kind of signal is judged by the time from falling edge to rising edge of the signal.
The detected TCO code is stored in "tco_code" and it is analyzed in the second, the minute, the hour, the week, the day, the month and the year by the time decoding processing. The information on the month and the day are not included in TCO. The leap year and the normalized day information (sum total day from January 1st) are included. The processing which changes into the information the month and the day based on them is executed with this equipment.


* Key push detection ( Every 10mS ) Software flow chart (9/11), Software flow chart (10/11)

The control ports of the keys(F2, F3, F4 and timer-OFF) and the LCD are sharing. Therefore, when detecting a key condition, RB4, RB5, RB6 and RB7 should be changed to the input mode from the output mode. It is again returned to the output mode when the key condition detection ends.
When a key push was detected, the number of the key which was pushed is checked. The number of the key is stored in "key_dat".
When a key is continuously pushed, it does the same operation when operating more than one time like a keyboard operation of the PC. This is for operation to be simplified. This operation is managed using "key_sts". When setting "key_sts" to "1", it becomes a key processing request. Because it is, when detecting continuous key operation, the effect which is the same when operating more than one time is gotten by setting "key_sts" by the specific time. On the flow chart, some of the parts of the set/clear of "key_sts" is shown. It is not all. For details, please refer to the source code.
The update speed by the continuing push time changes as follows.



Continuing push time	Update speed
to 500mS	no updat automatically
500mS to 2400mS	every 300mS
over 2400mS	every 100mS



The operation of the timer time setting can be done quickly by this function.
However, this function works by all key operation in addition to the time setting. So, when pushing Menu key continuously from the condition of the time display, it repeats the following operation.
Time display screen -> Timer selection screen -> 12H/24H mode selection screen -> Time display screen ... (Repeat)
This prevention processing isn't done.

Every time the data of 1 character is received with the serial circuit, the interruption occurs.
Reception processing itself is executed with the hardware of PIC. Even if the reception interruption occurs, it isn't always normally received. Therefore, in the beginning of the reception interruption processing, the confirmation whether or not which was normally received is done. In the malfunction in the reception operation, there are following two kinds.


Framing error : When the stop bit can not be detected in the signal from the serial circuit
Overrun error : When the following data is sent from the serial circuit while not reading contents in the reception buffer


When above-mentioned error occurs, a received data is canceled and the initialization of the reception circuit is done.
The framing error occurs with the noise. Also, it occurs to the thing except the above when the speed specification of the sender and receiving end aren't right. The overrun error occurs when the reception processing of software isn't working normally. It's when the data which was received with the hardware isn't read by the software. It doesn't occur if the software doesn't have a bug.
When the result of above-mentioned error checking is normally, received data is stored in the memory address which "rx_ptr" shows. The reception of the command ends when receiving CR(Carriage Return : It returns a print head to the origin) information as the received data. LF(Line Feed) is the signal which proceeds with the paper for 1 line. These signals are a data format from the time when the printer of the typewriter formula was used.