CHAPTER 4 BUS CONTROL FUNCTION
User’s Manual U13850EJ6V0UD
136
4.7.2 Bus hold procedure
The procedure of the bus hold function is illustrated below.
Figure 4-7. Bus Hold Procedure
HLDRQ
HLDAK
<1> <2> <3><4><5>
<7><8><9>
<6>
<1>HLDRQ = 0 acknowledged
<2>All bus cycle start requests held pending
<3>End of current bus cycle
<4>Bus idle status
<5>HLDAK = 0
<6>HLDRQ = 1 acknowledged
<7>HLDAK = 1
<8>Clears pending bus cycle start requests
<9>Start of bus cycle
Normal status
Bus hold status
Normal status
4.7.3 Operation in power save mode
In the IDLE or software STOP 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 V850/SB1
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