< 7/19>SMPC User's Manual/2.5 RTC Command

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SMPC User's Manual/Chapter 2 SMPC Commands

■2.5 RTC commands

Details of RTC commands are shown in table format. The table of each command and notes are as follows. In addition, by using status flags in all commands, you can manage double issuing of commands.

●SMPC interrupt

Items marked as "occurrence" generate an SMPC interrupt to the SH-2 via the SCU at the end of the command. Additionally, interrupts can be enabled/disabled by setting the SCU.

●IREG, OREG

Details of IREG and OREG used in the command are shown.
Command parameters are parameters that are set in IREG before issuing the command.
Result parameters are parameters set in OREG by command execution.
Result parameter OREG31 is set by SMPC when command processing begins. The command code is output to OREG31. By using it together with status flag (SF),

By using it together with status flag (SF),

Which command is being executed ( SF=1 )
Which command finished ( SF=0 )

can be judged.

●Execution time

The execution time is calculated from the number of steps in the SMPC internal firmware. If there is a conflict with an internal task such as RTC increment, the command execution time will change, so it is described in the range of minimum and maximum values.

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No.1

SETTIME

Time setting

Command code 16H SMPC interrupt generation disabled IREG 0 to 6 OREG 31 Execution time max=xxx 　　　　　　　　min=70μsec

Functional details

Set RTC time.

command parameters

		bit7	bit3
OREG0	20100001H	Year 1000 (BCD)	Year 100 (BCD)
OREG1	20100003H	Year number 10 (BCD)	First place in the Western calendar (BCD)
OREG2	20100005H	Day of the week (hexadecimal) Note 1	Month (hexadecimal) Note 2
OREG3	20100007H	10th place per day (BCD)	No. 1 per day (BCD)
OREG4	20100009H	10th position (BCD)	1st place (BCD)
OREG5	2010000BH	Tenth place (BCD)	Minute 1st place (BCD)
OREG6	2010000DH	Ten seconds (BCD)	Second place (BCD)

Note 1

day of week	Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
value	0H	1H	2H	3H	4H	5H	6H

Note 2

Month	January	February	March	April	May	June	July	August	September	October	November	December
value	1H	2H	3H	4H	5H	6H	7H	8H	9H	AH	BH	CH

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	1	0	1	1	0

remarks

●The time is initialized to " 23:59:59, Friday, December 31, 1993 " at the time of SMPC cold reset and starts counting.

SMPC cold reset occurs under the following conditions

When you press the reset switch inside the battery box on the back of Sega Saturn
When the main power is turned on (ON) when the battery is not installed or when the battery is exhausted
When the battery is inserted while the power is OFF

●If you set data that does not actually exist, a day of the week 7 or more, a month 13 or more, a date that does not correspond to a month (leap year correction is corrected up to 2099), a time 24 or more, minutes and seconds 60 or more, The set value and subsequent count will be undefined.

●If the power is turned OFF while the SETTIME command is being issued,

If the internal processing of the SETTIME command can be executed before the power OFF sequence, all data will be updated.
If the power OFF sequence is executed first, the data before the command is issued will be retained.

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