Force SYS68K/CPU-30 R4, Техническое справочное руководство

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Hardware Description SYS68K/CPU-30 R4 Technical Reference Manual
Page 56
3.8.4 Backup Power
for the RTC There are two sources for backup power. One from the VMEbus
+5VSTDBY line and the other one from a CR2032-type lithium battery
installed in the battery socket at location BAT 1.
Backup power from the 5VSTDBY line is enabled by
SW11-2. Backup power from the battery is enabled by SW11-1.
The RTC is powered by backup power circuitry. This circuitry maintains
power supply for the RTC to guarantee continuous operation.
Under normal operation the backup power circuitry connects the +5V
power supply to the RTC. When the main +5V supply fails, backup
power may be supplied from one of two alternate sources. The VMEbus
+5VSTDBY line may be used to provide backup power under power-fail
conditions. The switchover from 5V to +5VSTDBY is fully
automatic; whichever voltage is higher will be available to the RTC.
As a second alternative, the backup power may be supplied by an on-
board lithium battery. Should the +5V and/or +5VSTDBY supplies drop
below approxi3.3 volts, the on-board battery will be used.
This is controlled for +5VSTDBY by switch SW11-2.
rtc->fcontrol = 5;
rtc->fcontrol = 4; /* 24-hour clock */
rtc->sec10reg = sy->_ssec[0]/10;
rtc->sec1reg = sy->_ssec[0]%10;
rtc->min10reg = (char)(sy->_smin/10);
rtc->min1reg = (char)(sy->_smin%10);
rtc->hou10reg = (char)(sy->_shrs/10);
rtc->hou1reg = (char)(sy->_shrs%10);
rtc->yr10reg = sy->_syrs[0]/10;
rtc->yr1reg = sy->_syrs[0]%10;
rtc->day10reg = sy->_sday/10;
rtc->day1reg = sy->_sday%10;
rtc->mon10reg = sy->_smon/10;
rtc->mon1reg = sy->_smon%10;
rtc->dcontrol = 0; /* start clock */
}
SW11-2 Description
OFF (default) Backup from +5VSTDBY for RTC and SRAM disabled
ON Backup from +5VSTDBY for RTC and SRAM enabled