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Section 2 Software Specifications when Using the SH7781

Rev. 2.00 Jan. 28, 2008 Page 10 of 32

REJ10J1422-0200

3. Low-Power States (Sleep and Module Standby)

For low-power consumption, the SH7781 has sleep and module standby states.

The sleep and module standby states are switched using the SLEEP instruction. When the

emulator is used, the sleep state can be cleared with either the normal clearing function or with

the [STOP] button, and a break will occur.

Note: The memory must not be accessed or modified in sleep state.

4. Reset Signals

The SH7781 reset signals are only valid during emulation started with clicking the GO or

STEP-type button. If these signals are enabled on the user system in command input wait

state, they are not sent to the SH7781.

Note: Do not break the user program when the _PRESET or _BREQ signal is being low and the

WAIT control signal is being active. A TIMEOUT error will occur. If the WAIT control

signal and the _BREQ signal are fixed to active and low during break, respectively, a

TIMEOUT error will occur at memory access.

5. Direct Memory Access Controller (DMAC)

The DMAC operates even when the emulator is used. When a data transfer request is

generated, the DMAC executes DMA transfer.

6. Memory Access during User Program Execution

When a memory is accessed from the memory window, etc. during user program execution,

the user program is resumed after it has stopped in the emulator to access the memory.

Therefore, realtime emulation cannot be performed.

The stopping time of the user program is as follows:

Environment:

Host computer: 800 MHz (Pentium

III)

JTAG clock: 30 MHz (TCK clock)

When a one-byte memory is read from the command-line window, the stopping time will be

about 45 ms.

7. Memory Access during User Program Break

The emulator can download the program for the flash memory area (for details, refer to section

6.22, Download Function to the Flash Memory Area, in the SH-4A, SH4AL-DSP E200F

Emulator User’s Manual). Other memory write operations are enabled for the RAM area.

Therefore, an operation such as memory write or BREAKPOINT should be set only for the

RAM area.

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