CHAPTER 4 BUS CONTROL FUNCTION
User’s Manual U13850EJ4V0UM
114
4.7.2 Bus hold procedure
The procedure of the bus hold function is illustrated below.
Figure 4-10. Bus Hold Procedure
HLDRQ
HLDAK
<1> <2> <3><4><5>
<7><8><9>
<6>
<1>HLDRQ = 0 accepted
<2>All bus cycle start request pending
<3>End of current bus cycle
<4>Bus idle status
<5>HLDAK = 0
<6>HLDRQ = 1 accepted
<7>HLDAK = 1
<8>Clears bus cycle start request pending
<9>Start of bus cycle
Nomal status
Bus hold status
Normal status
4.7.3 Operation in power save mode
In the STOP or IDLE mode, the system clock is stopped. Consequently, the bus hold status is not set even if the
HLDRQ pin becomes active.
In the HALT mode, the HLDAK pin immediately becomes active when the HLDRQ pin becomes active, and the
bus hold status is set. When the HLDRQ pin becomes inactive, the HLDAK pin becomes inactive. As a result, the
bus hold status is cleared, and the HALT mode is set again.
Содержание MPD703030A
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