TMS470R1VC334A

16/32-BIT RISC ROM MICROCONTROLLER

SPNS080A – MARCH 2004 – REVISED MARCH 2006

11

POST OFFICE BOX 1443

memory selects

Memory selects allow the user to address memory arrays (i.e., ROM, RAM, and HET RAM) at user-defined

addresses. Each memory select has its own set (low and high) of memory base address registers (MFBAHRx

and MFBALRx) that, together, define the array’s starting (base) address, block size, and protection.

The base address of each memory select is configurable to any memory address boundary that is a multiple

of the decoded block size. The decoded block size for the ROM memory on this device is 0x00100000. For

more information on how to control and configure these memory select registers, see the bus structure and

memory sections of the TMS470R1x System Module Reference Guide (literature number SPNU189).

For the memory selection assignments and the memory selected, see Table 2.

Table 2. Memory Selection Assignment

† The starting addresses for both RAM memory-select signals cannot be offset from each other by a multiple of the user-defined block size in the

memory-base address register.

RAM

The VC334A device contains 4K bytes of internal static RAM configurable by the SYS module to be addressed

within the range of 0x0000_0000 to 0xFFE0_0000. This VC334A RAM is implemented in one 4K array selected

by two memory-select signals. This VC334A configuration imposes an additional constraint on the memory

map for RAM; the starting addresses for both RAM memory selects cannot be offset from each other by the

multiples of the size of the physical RAM (i.e., 4K for the VC334A device). The VC334A RAM is addressed

through memory selects 2 and 3.

The RAM can be protected by the memory protection unit (MPU) portion of the SYS module, allowing the user

finer blocks of memory protection than is allowed by the memory selects. The MPU is ideal for protecting an

operating system while allowing access to the current task. For more detailed information on the MPU portion

of the SYS module and memory protection, see the memory section of the TMS470R1x System Module

Reference Guide (literature number SPNU189).

ROM

The VC334A program ROM consists of 64K bytes mask programmable read-only memory. The program ROM

is used for permanent storage of data or instructions. Programming the mask ROM is performed at the time of

device fabrication.

HET RAM

The VC334A device contains HET RAM. The HET RAM has a 64-instruction capability. The HET RAM is

configurable by the SYS module to be addressed within the range of 0x0000_0000 to 0xFFE0_0000. The HET

RAM is addressed through memory select 4.

MEMORY

SELECT

MEMORY SELECTED

(ALL INTERNAL)

MEMORY

SIZE

MPU

MEMORY BASE ADDRESS REGISTER

STATIC MEM

CTL REGISTER

0 (fine)

ROM

64K

NO

MFBAHR0 and MFBALR0

1 (fine)

ROM

NO

MFBAHR1 and MFBALR1

2 (fine)

RAM

YES

MFBAHR2 and MFBALR2

3 (fine)

RAM

YES

MFBAHR3 and MFBALR3

4 (fine)

HET RAM

1K

MFBAHR4 and MFBALR4

SMCR1