4. Memory and Bus System
0 1 2 3
4
ARM Cortex-M
DMA Controller
RAM
Peripherals
Flash
Quick Facts
What?
A low latency memory system including low energy
Flash and RAM with data retention which makes the
energy modes attractive.
Why?
RAM retention reduces the need for storing data in
Flash and enables frequent use of the ultra low en-
ergy modes EM2 DeepSleep and EM3 Stop.
How?
Low energy and non-volatile Flash memory stores
program and application data in all energy modes
and can easily be reprogrammed in system. Low
leakage RAM with data retention in EM0 Active to
EM3 Stop removes the data restore time penalty,
and the DMA ensures fast autonomous transfers
with predictable response time.
4.1 Introduction
The EFM32 Jade Gecko contains an AMBA AHB Bus system to allow bus masters to access the memory mapped address space. A
multilayer AHB bus matrix connects the 4 master bus interfaces to the AHB slaves (
Figure 4.1 EFM32 Jade Gecko Bus System on
). The bus matrix allows several AHB slaves to be accessed simultaneously. An AMBA APB interface is used for the peripher-
als, which are accessed through an AHB-to-APB bridge connected to the AHB bus matrix. The 4 AHB bus masters are:
•
Cortex-M3 ICode:
Used for instruction fetches from Code memory (valid address range: 0x00000000 - 0x1FFFFFFF)
•
Cortex-M3 DCode:
Used for debug and data access to Code memory (valid address range: 0x00000000 - 0x1FFFFFFF)
•
Cortex-M3 System:
Used for data and debug access to system space. It can access entire memory space except Code memory
(valid address range: 0x20000000 - 0xFFFFFFFF)
•
DMA:
Can access entire memory space except internal core memory region and Code memory (valid address range: 0x20000000 -
0xDFFFFFFF)
ARM
Cortex-M
AHB Multilayer
Bus Matrix
DCode
System
DMA
Flash
RAM
AHB/
APB
Bridge
ICode
CRYPTO
Peripheral 0
Peripheral n
Figure 4.1. EFM32 Jade Gecko Bus System
EFM32JG1 Reference Manual
Memory and Bus System
silabs.com
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