Motorola MPC8260 User Manual

10-30

MOTOROLA

The 60x bus assigned UPM refresh timer register (PURT) is shown in Figure 10-14. 

Table 10-12 describes PURT Þelds. 

The local bus assigned UPM refresh timer register (LURT) is shown in Figure 10-15. 

0Ð31

A

Memory address. The memory address register can be output to the address lines under control of 
the AMX bits in the UPM

Bit

0

1

2

3

4

5

6

7

Field

PURT

Reset

0000_0000

R/W

R/W

Addr

0Ð7

PURT

Refresh timer period. Determines the timer period according to the following equation:

This timer generates a refresh request for all valid banks that selected a UPM machine assigned to 
the 60x bus (MxMR[BSEL] = 0) and is refresh-enabled (MxMR[RFEN] = 1). Each time the timer 
expires, a qualiÞed bank generates a refresh request using the selected UPM. The qualiÞed banks 
are rotating their requests. 
Example: For a 25-MHz SYSTEM CLOCK and a required service rate of 15.6 µs, given 
MPTPR[PTP] = 32, the PURT value should be 12 decimal. 12/(25 MHz/32) = 15.36 µs, which is less 
than the required service period of 15.6 µs.

Bit

0

1

2

3

4

5

6

7

Field

LURT

Reset

0000_0000

R/W

R/W

Addr

TimerPeriod

PURT

F

MPTC

-----------------

è

ø

æ

ö

=