Application Examples
EXAMPLE 3: REAL-TIME CLOCK DRIVERS
Objectives
•
Write the read and write routines which can initialize the time
and read it back.
•
Write the real-time clock access routine, which is required
before reading or writing the clock.
System Configuration
The ZT 8809A must be configured for the factory default jumper
assignments for this example. It is assumed that STD DOS is not
installed, since the clock is handled by STD DOS.
Software Outline
INIT_CLK Routine
BEGIN
Perform one read from the real-time clock to reset the
signature comparator
Send the 64-byte string to the real-time clock
END
READ_CLK Routine
BEGIN
Read 64 bytes from the real-time clock
Massage the data into separate bytes
4-40
