Altera Active Serial Memory Interface - Manual (Page 21)

Protect a Sector on the EPCS/EPCQ/EPCQ-L Device
Use the
sector_protect
signal to instruct the IP core to protect a sector on the EPCS/EPCQ/EPCQ-L
device.
Figure 5: Protecting a Sector
This figure shows an example of the latency when the Altera ASMI Parallel IP core is executing the sector
protect command. The latency shown does not correctly reflect the true processing time. It shows the
command only.
This command writes the EPCS/EPCQ/EPCQ-L status register to set the block protection bits.
The block protection bits show which sectors are protected from write or erase, and provide
protection in addition to that provided by the
wren
signal.
You can set the block protection bits in the EPCS/EPCQ/EPCQ-L status register to protect those
sectors that contain configuration data, and are not intended for general-purpose memory usage.
Ensure that the 8-bit code is available on the
datain[7..0]
signal before asserting the
sector_protect
and
wren
signals. The IP core registers the
sector_protect
signal at the
positive edge of the
clkin
signal.
The IP core asserts the
busy
signal as soon as it receives the
sector_protect
signal. The
busy
signal remains asserted while the EPCS/EPCQ/EPCQ-L status register is written.
If the
wren
signal has a value of zero, the IP core will not carry out the
sector_protect
signal,
and the
busy
signal remains deasserted.
Note: If you keep the
wren
and
sector_protect
signals asserted while the
busy
signal is
deasserted after the IP core has finished processing the sector protect command,
the IP core re-registers the
wren
and
sector_protect
signals as a value of one and
carries out another write status register operation. Therefore, before the IP core
deasserts the
busy
signal, you must deassert the
sector_protect
signal.
The IP core uses only bits 2 to 3, or 2 to 4 for EPCS devices, and 2 to 5, or 2 to 6 for EPCQ/EPCQ-
L devices out of the 8 bits for block protection. The rest of the bits have other meanings for the
ASMI operation, and cannot be overwritten by the sector protect operation. Whenever the input
address is in a protected sector, the IP core omits the operation and the
busy
signal remains
deasserted.
UG-ALT1005
2014.12.15
Protect a Sector on the EPCS/EPCQ/EPCQ-L Device 21
Altera ASMI Parallel IP Core User Guide Altera Corporation
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