AT91SAM9G45-EKES Atmel, AT91SAM9G45-EKES Datasheet - Page 48

• Manufacturer Part Number: AT91SAM9G45-EKES
• Description: KIT EVAL FOR AT91SAM9G45
• Manufacturer: Atmel
• Series: AT91SAM Smart ARMr
• Type: MCUr

Specifications of AT91SAM9G45-EKES

• Contents: Board
• Processor To Be Evaluated: SAM9G45
• Data Bus Width: 32 bit
• Interface Type: I2C, SPI, UART
• Maximum Operating Temperature: + 50 C
• Minimum Operating Temperature: - 10 C
• Operating Supply Voltage: 1.8 V to 3.3 V
• For Use With/related Products: AT91SAM9G45
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: Q4626953

9.8
9.8.1
9.8.2
9.8.3
48
Tightly-Coupled Memory Interface
AT91SAM9G45
TCM Description
Enabling and Disabling TCMs
TCM Mapping
The ARM926EJ-S processor features a Tightly-coupled Memory (TCM) interface, which enables
separate instruction and data TCMs (ITCM and DTCM) to be directly reached by the processor.
TCMs are used to store real-time and performance critical code, they also provide a DMA sup-
port mechanism. Unlike AHB accesses to external memories, accesses to TCMs are fast and
deterministic and do not incur bus penalties.
The user has the possibility to independently configure each TCM size with values within the fol-
lowing ranges, [0K Byte, 64K Bytes] for ITCM size and [0K Byte, 64K Bytes] for DTCM size.
TCMs can be configured by two means: HMATRIX TCM register and TCM region register (regis-
ter 9) in CP15 and both steps should be performed. HMATRIX TCM register sets TCM size
whereas TCM region register (register 9) in CP15 maps TCMs and enables them.
The data side of the ARM9EJ-S core is able to access the ITCM. This is necessary to enable
code to be loaded into the ITCM, for SWI and emulated instruction handlers, and for accesses to
PC-relative literal pools.
Prior to any enabling step, the user should configure the TCM sizes in HMATRIX TCM register.
Then enabling TCMs is performed by using TCM region register (register 9) in CP15. The user
should use the same sizes as those put in HMATRIX TCM register. For further details and pro-
gramming tips, please refer to chapter 2.3 in ARM926EJ-S TRM.
The TCMs can be located anywhere in the memory map, with a single region available for ITCM
and a separate region available for DTCM. The TCMs are physically addressed and can be
placed anywhere in physical address space. However, the base address of a TCM must be
aligned to its size, and the DTCM and ITCM regions must not overlap. TCM mapping is per-
formed by using TCM region register (register 9) in CP15. The user should input the right
mapping address for TCMs.
6438F–ATARM–21-Jun-10