Motorola MPC860 PowerQUICC, User Manual, Page: 459 / 1106

MOTOROLA Chapter 16. Memory Controller 16-33
Part IV. Hardware Interface
16.6.2 Programming the UPM
The UPM is a microsequencer that requires microinstructions or RAM words to generate
signal timings for different memory cycles. Program the UPMs in the following steps:
1. Write patterns into the RAM array.
2. Program MPTPR
3. Program the machine mode register (MAMR and MBMR).
4. Set up BRx and ORx.
16.6.3 Clock Timing
Fields in the RAM word specify the value of the various external signals at each clock edge.
The signal timing generator causes external signals to behave according to the timing
speciÞed in the current RAM word. Figure 16-34 and Figure 16-35 show the clock schemes
of the UPMs in the memory controller. The clock phases shown reßect timing windows
during which generated signals can change state. Figure 16-34 shows the clock scheme
selected when the SCCR[EBDF] = 00; CLKOUT is the same as system clock.
Figure 16-34. UPM Clock Scheme One (Division Factor = 1)
In Figure 16-35, if SCCR[EBDF] = 01, CLKOUT equals the system clock divided by 2. In
this scheme GCLK1_50 does not have a 50% duty cycle.
Figure 16-35. UPM Clock Scheme Two (Division Factor = 2)
System Clock
CLKOUT
GCLK1_50
GCLK2_50
Clock Phase 1 2 3 4 1 2 3 4
System Clock
CLKOUT
GCLK1_50
GCLK2_50
Clock Phase 1 2 3 4 1 2 3 4