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GR716-DS-UM, May 2019, Version 1.29
467
www.cobham.com/gaisler
GR716
47
AMBA Protection Unit
The GR716 microcontroller comprises two separate AMBA memory protection units (MEMPROT).
The MEMPROT units described in this section have the capability to detect and protect memory areas
from write accesses.
The first AMBA memory protection units (MEMPROT0) is connected to Main AHB bus and the sec-
ond AMBA memory protection units (MEMPROT1) is connected to the DMA AMBA bus. Each
AMBA memory protection unit has a unique AMBA address described in chapter 2.11 for configura-
tion and status.
The control and status registers for the AMBA memory protection units are located on the APB bus in
the address range from 0x80005000 to 0x80005FFF and in the range from 0x8010A000 to
0x8010AFFF. See AMBA memory protection units connections in the next drawing. The figure
shows memory locations and functions used for AMBA memory protection units configuration and
control.
The primary clock gating unit
GRCLKGATE
described in section 26 is used to enable/disable the
AMBA memory protection units. The unit
GRCLKGATE
can also be used to perform reset of indi-
vidual AMBA memory protection units. Software must enable clock and release reset described in
section 26 before configuration.
The system can be configured to protect and restrict access to the AMBA memory protection units.
47.1
Overview
The AMBA Protection unit allows user to define memory segments for protection, memory segments
are defined by an start and stop address, to which write permissions can be set. The AMBA protection
unit supports up to four individual segments for the system bus and four segments for the dma bus.
The memory protection unit can also restrict write access to individual APB slave interface for spe-
cific AHB masters. The restriction needs to be enabled by the user or software. It should be noted that
write access to registers in the memory protection can not be restricted to prevent situation where the
system can’t control APB accesses.
The LEON3FT microcontroller includes 2 separate memory protection units hence register map is
split into separate chapters for system and dma bus. The first protection unit monitors masters
accesses on the system bus and the second protection unit monitors masters accesses on the DMA bus.
Figure 82.
GR716 MEMPROTx bus connection
LEON3FT
Processor
APB4
Main AHB
(0x00000000-
0xFFFFFFFFF)
DMA
AHB
Bridge
Memory Protection
(0x8010A000 -
0x8010AFFF)
APB1
APB2
APB3
IMEM
128K
DMEM
64K
Memory Protection
(0x80005000 -
0x80005FFF)
MEMPROT1
Bridge4
Bridge0
Bridge1
Bridge3
MEMPROT2
AMB
A
FTMCTRL
write protection
write detection
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