Chapter 7: User Flash Memory in MAX V Devices
7–7
UFM Functional Description
Oscillator
OSC_ENA, one of the input signals in the UFM block, is used to enable the oscillator
signal to output through the OSCoutput port. You can use this OSCoutput port to
connect with the interface logic in the logic array. It can be routed through the logic
array and fed back as an input clock for the address register (ARCLK) and the data
register (DRCLK). The output frequency of the OSCport is one-fourth that of the
oscillator frequency. As a result, the frequency range of the OSCport is 3.9 to 5.3 MHz.
The maximum clock frequency accepted by ARCLKand DRCLKis 10 MHz and the duty
cycle accepted by the DRCLKand ARCLKinput ports is approximately 45% to 50%.
When the OSC
_
ENAinput signal is asserted, the oscillator is enabled and the output is
ENAsignal is set low,
routed to the logic array through the OSCoutput. When the OSC
_
the OSCoutput drives constant high. The routing delay from the OSCport of the UFM
block to OSCoutput pin depends on placement. You can analyze this delay using the
TimeQuest timing analyzer.
The undivided internal oscillator, which is not accessible, operates in a frequency
range from 15.6 to 21.2 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
To see how specific operating modes of the ALTUFM megafunction handle OSC
_
ENAport is asserted.
ENA
_
and the oscillator, refer to “Software Support for UFM Block” on page 7–13. For user-
generated logic interfacing to the UFM, the oscillator must be enabled during
program or erase operations, but not during read operations. The OSC_ENAsignal can
be tied low if you are not issuing any PROGRAM or ERASE commands.
1
1
During real-time ISP operation, the internal oscillator automatically enables and
outputs through the OSCoutput port (if this port is instantiated) even though the
OSC_ENAsignal is tied low. You can use the RTP_BUSYsignal to detect the beginning and
ending of the real-time ISP operation for gated control of this self-enabled OSCoutput
condition.
The internal oscillator is not enabled all the time. The internal oscillator for the
program or erase operation is only activated when the flash memory block is being
programmed or erased. During a read operation, the internal oscillator is activated
whenever the flash memory block is reading data.
Instantiating the Oscillator without the UFM
You can use the MAX II/MAX V 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. Figure 7–4 shows the
ALTUFM_OSC megafunction instantiation in the Quartus II software.
Figure 7–4. The Quartus II ALTUFM_OSC Megafunction
January 2011 Altera Corporation
MAX V Device Handbook
ALTERA [ ALTERA CORPORATION ]
