Altera RAM Initializer - Manual (Page 31)

Altera Corporation Confidential—Internal Use Only 2–19
May 2008 RAM Initializer (ALTMEM_INIT) Megafunction User Guide
Getting Started
Figure 2–15 also shows that the assertion of the init signal does not
affect the current initialization process while the init_busy signal is
high. The init signal is asserted only once to begin the initialization; to
re-initialize the RAM, you must wait until the current initialization is
complete.
Figure 2–16 shows the RAM initialization process at completion.
Figure 2–16. Design Example 2: RAM Initialization at Completion
At 337,500 ps, the last value, 0x1f, appears at the output port of the RAM.
The init_busy signal is deasserted to indicate the end of initialization.
1
If the external ROM has both its input and output ports
registered, and the ROM_READ_LATENCY is set to 1, the last
initialization data is not written to the RAM.
Conclusion The ALTMEM_INIT megafunction is designed specifically to support the
RAM initialization in HardCopy devices and Stratix devices that are
migratable to HardCopy devices. You can also use it for other Altera
devices that come with RAM.
The megafunction offers different initialization modes with either an
initialization data file or an external ROM, providing you with the
flexibility to choose a mode that suits your application. You can also select
the appropriate latency mode to control the initialization process
according to your design specifications.