Chapter 7: User Flash Memory in MAX V Devices
7–11
UFM Operating Modes
Erase
The ERASEsignal initiates an erase sequence to erase one sector of the UFM. The data
register is not needed to perform an erase sequence. To indicate the sector of the UFM
to be erased, the MSB of the address register should be loaded with 0 to erase UFM
sector 0, or 1 to erase UFM sector 1 (Figure 7–2 on page 7–5). On a rising edge of the
ERASEsignal, the memory sector indicated by the MSB of the address register will be
erased. The BUSYsignal is asserted until the erase sequence is completed. The address
register should not be modified until the BUSYsignal is de-asserted to prevent the flash
content from being corrupted. This ERASEsignal is ignored when the BUSYsignal is
asserted. Figure 7–8 illustrates the UFM waveforms during erase mode.
1
When the UFM sector is erased, it has 16-bit locations all filled with FFFF. Each UFM
storage bit can be programmed only once between erase sequences. You can write to
any word up to two times providing the second programming attempt at that location
only adds 0s. 1s are mask bits for your input word that cannot overwrite 0s in the
flash array. New 1s in the location can only be achieved by an erase. Therefore, it is
possible for you to perform byte writes because the UFM array is 16 bits for each
location.
Figure 7–8. UFM Erase Waveforms
ARSHFT
ARCLK
ARDin
9 Address Bits
tACLK
tAH
tASU
tADH
tADS
DRSHFT
DRCLK
DRDin
DRDout
OSC_ENA
tOSCS
tOSCH
PROGRAM
ERASE
tEB
tBE
BUSY
tEPMX
January 2011 Altera Corporation
MAX V Device Handbook
ALTERA [ ALTERA CORPORATION ]
