Chapter 9: Using User Flash Memory in MAX II Devices
UFM Functional Description
9–7
The undivided internal oscillator, which is not accessible, operates in a frequency
range from 13.33 to 22.22 MHz. The internal oscillator is enabled during power-up, in-
system programming, and real-time ISP. At all other times, the oscillator is not
running unless the UFM is instantiated in the design and the
OSC_ENA
port is
asserted. To see how specific operating modes of
ALTUFM
handle
OSC_ENA
and the
oscillator, refer to
For user
generated logic interfacing to the UFM, the oscillator must be enabled during
PROGRAM
or
ERASE
operations, but not during
READ
operations.
OSC_ENA
can be tied
low if you are not issuing any
PROGRAM
or
ERASE
commands.
1
During real-time ISP operation, the internal oscillator automatically enables and
outputs through the
OSC
output port (if this port is instantiated) even though the
OSC_ENA
signal is tied low. You can use the
RTP_BUSY
signal to detect the beginning
and ending of the real-time ISP operation for gated control of this self-enabled
OSC
output condition.
The internal oscillator is not enabled all the time. The internal oscillator for the
program/erase
operation is only activated when the flash memory block is being
programmed or erased. During the
READ
operation, the internal oscillator is activated
whenever the flash memory block is reading data.
1
Instantiating the Oscillator without the UFM
You can use the IO/MAX II oscillator megafunction selection in the MegaWizard
®
Plug-In Manager to instantiate the UFM oscillator if you intend to use this signal
without using the UFM memory block.
shows the altufm_osc
megafunction instantiation in the Quartus II software.
Figure 9–4.
The Quartus II altufm_osc Megafunction
This megafunction is in the I/O folder on page 2a of the MegaWizard
®
Plug-In
Manager, as shown in
You can start the MegaWizard Plug-In Manager on
the Tools menu.
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