EP80579 Datasheet, PDF (1636/1916 Pages) Intel Corporation – Intel® EP80579 Integrated Processor Product Line

Intel^® EP80579 Integrated Processor
41.5.6
Target Time Expiration
A system time that is greater than or equal to the target time sets the target time
expiration condition and generates an interrupt if enabled.
Two independent target times are supported.
Refer to Section 41.6.1.11, “Offset 0028h: TS_TrgtLo - Target Time Low Register” and
Section 41.6.1.12, “Offset 002Ch: TS_TrgtHi - Target Time High Register”.
Also, Section 41.6.1.28, “Offset 01F0h: TS_Aux_TrgtLo - Auxiliary Target Time Low
Register” and Section 41.6.1.29, “Offset 01F4h: TS_Aux_TrgtHi -Auxiliary Target Time
High Register”
41.5.7
System Time
The system timer is derived from the source clock through a frequency divider. The
frequency divider is based on the value in the Addend register. Once every system clock
cycle the value in the Addend register is added to the value in the Accumulator register.
When the accumulator register rolls over, the system timer is incremented.
A single SourceClock is provided from which the desired SystemClock can be derived
via a frequency divider. The frequency divider is implemented by using the Addend
register. Once every SourceClock cycle the value in the Addend register is added to the
value in the Accumulator register. When the accumulator register rolls over, the system
timer is incremented. Thus, the system timer is incremented once every SystemClock
period.
The value in the Addend register represents the frequency compensation value. This
value is determined as follows:
FreqDivisionRatio = FreqOscillator / FreqClock
The equation for the frequency compensation value utilizes the precision of the
accumulator and the FreqDivisionRatio. Since the accumulator is 32 bits, the following
equation applies:
FreqCompensationValue = 2³² / FreqDivisionRatio
The hexadecimal representation of the FreqCompensationValue is the value that is
written to the Addend register. The following table gives examples of addend values
based on a 66.67 MHz FreqOscillator:
Table 41-9. Addend Values
FreqOscillator¹
FreqClock
FreqDivisionRatio
FreqCompensationValue
66.67 MHz
40 MHz
1.67
0x994B1D20
66.67 MHz
50 MHz
1.33
0xC07B301E
66.67 MHz
60 MHz
1.11
0xE6A17102
1.
50 MHz for 600 MHz IA-32 core and 66.67 MHz for 1066 MHz/1200 MHz IA-32 core.
Intel^® EP80579 Integrated Processor Product Line Datasheet
1636
August 2009
Order Number: 320066-003US