MAC7200 datasheet(535/976 Pages) FREESCALE

535 / 976 page

Functional Description

MAC7200 Microcontroller Family Reference Manual, Rev. 2

Freescale Semiconductor

457

25.4

Functional Description

This section provides a complete functional description of the System Services Module. The primary

purpose of the SSM is to provide information about the current state and configuration of the system that

may be useful for configuring application software and for debug of the system.

25.4.1

System Configuration/Status

The MAC7200 provides three registers in the SSM to aid in configuring software and debugging your

system:

•STATUS

•

MEMCONFIG

The STATUS register is a 16-bit read-only register that reflects the current status of the DMA, and is

primarily used for debug. By reading the STATUS register, you can determine which DMA channel, if any,

is currently active. This information should not be used as part of the execution of application code, but

Address Refer to Table 25-1

Access: Refer to

Table 25-12

9876543210

SYSRESET

RESET:

000000000000000

= Writes have no effect on this bit

rsvd

= Reserved for future use

Figure 25-6. System Reset (SYSRESET) Register

Table 25-11. SYSRESET Field Descriptions

Field

Description

15–0

SYS

RESET

Execute a system reset. This register enables software to reset the system. In order to prevent spurious resets, a

hardware interlock has been implemented. In order to reset the system, the following sequence of writes must be

executed:

• 16-bit Write of 0xb6b6

• 16-bit Write of 0x3535

Once the final write to the SYSRESET register is performed, the system will reset itself. If any value other than

0x3535 is written to the register after writing 0xb6b6, or an 8-bit write of the register is performed, the sequence must

be started again from the beginning. Once the final write is performed, the system will reset itself, with all further

writes to the register being ignored until the reset sequence is complete.

Table 25-12. SYSRESET Allowed Register Accesses

8-bit

16-bit

32-bit

READ

Allowed

WRITE

Not Allowed

Allowed

Not Allowed

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