12.3 Functional Description
An overview of the SMU module within the system is shown in
Figure 12.1 Bus-Level Security System View on page 365
.
Bus Matrix
ARM Core
Code
SRAM
Peripherals
MPU
PPU
Memory Space
SMU
IRQs
Control/Status
Figure 12.1. Bus-Level Security System View
12.3.1 PPU - Peripheral Protection Unit
The number of peripheral memory regions on the device exceeds the number of configurable regions available using the MPU. While it
is possible to manage finer granularity of memory security through software, the PPU provides a hardware solution for fine-grained pe-
ripheral-level protection to eliminate the performance degradation associated with a partially software-managed solution.
The PPU provides a hardware access barrier to any peripheral that is configured to be protected. When an attempt is made to access a
peripheral without the required privilege level, the PPU detects the fault and intercepts the access. No write or read of the peripheral
register space occurs, and an all-zero value is returned if the access is a read. See
for more details on how ac-
cess faults are reported to the CPU.
Note:
The CPU is the only system bus master in the EFR32 that can trigger access faults. All other masters are given full access privi-
leges and have no configurable context switching enabled.
Reference Manual
SMU - Security Management Unit
silabs.com
| Building a more connected world.
Rev. 1.1 | 365