Datum bc630AT, User Manual

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CHAPTER SIX
6-4 bc630AT Real Time Clock Module Datum Inc
outportb(BASE+COMMAND, 0x84); /* Issue 'Set RTC Chip Time' command */
do
{
time_delay(); /* Function slows polling rate to */
} /* < 500 KHz */
while (inportb(BASE+COMMAND) != 4); /* Wait for ready flag status of 4 */
/* Polling rate not to exceed 500 kHz*/
/* RTC Chip time successfully set */
6.4 SYNCHRONIZING THE RTC IC TO EXTERNAL TIME CODE
The following example illustrates how to synchronize the Battery Backed RTC IC time to the external
time code. Before synchronizing be sure RTC IC is loaded with the valid year. The example assumes
the year is accurately set in the RTC chip.
outportb(BASE+COMMAND, 0x93); /* Initialize bc630AT */
do
{
time_delay(); /* Function slows polling rate to */
} /* < 500 KHz */
while (inportb(BASE+COMMAND) != 0x13); /* Wait for ready value of 0x13 */
/* from bc630AT, indicating */
/* synchronization process */
/* initiated. Process will be */
/* complete in approximately two */
/* seconds */
/* Polling rate not to exceed */
/* 500 KHz */
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