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Section 12 Bus State Controller (BSC)
Rev. 4.00 Sep. 14, 2005 Page 400 of 982
REJ09B0023-0400
The sequence for reclaiming the bus mastership from an external device is described below. 1.5
cycles after the negation of
BREQ
is detected at the falling edge of CKIO, the bus control signals
are driven high. The bus enable signal is negated at the next falling edge of the clock. The fastest
timing at which actual bus cycles can be resumed after bus control signal assertion is at the rising
edge of the
CKIO where address and data signals are driven. Figure 12.48 shows the bus
arbitration timing.
While releasing the bus mastership, the SLEEP instruction (to enter the sleep mode or the standby
mode), as well as a manual reset, cannot be executed until the LSI obtains the bus mastership. The
BREQ
input signal is ignored in the standby mode and the
BACK
output signal are placed in the
high impedance state. If the bus mastership request is required in this state, the bus mastership
must be released by pulling down the
BACK
pin to enter the standby mode. The bus mastership
release (
BREQ
signal for high level negation) after the bus mastership request (
BREQ
signal for
low level assertion) must be performed after the bus usage permission (
BACK
signal for low level
assertion). If the
BREQ
signal is negated before the
BACK
signal is asserted, only one cycle of the
BACK
signal is asserted depending on the timing of the
BREQ
signal to be negated and this may
cause a bus contention between the external device and the LSI.
CKIO
Other bus
contorol sigals
BREQ
BACK
A25 to A0
D31 to D0
CSn
Figure 12.48 Bus Arbitration Timing (Clock Mode 7 or CMNCR.HIZCNT = 1)
Содержание HD6417641
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Страница 11: ...Rev 4 00 Sep 14 2005 Page xi of l USB Universal serial bus WDT Watch dog timer...
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Страница 204: ...Section 4 Clock Pulse Generator CPG Rev 4 00 Sep 14 2005 Page 154 of 982 REJ09B0023 0400...
Страница 212: ...Section 5 Watchdog Timer WDT Rev 4 00 Sep 14 2005 Page 162 of 982 REJ09B0023 0400...
Страница 228: ...Section 6 Power Down Modes Rev 4 00 Sep 14 2005 Page 178 of 982 REJ09B0023 0400...
Страница 246: ...Section 8 X Y Memory Rev 4 00 Sep 14 2005 Page 196 of 982 REJ09B0023 0400...
Страница 318: ...Section 11 User Break Controller UBC Rev 4 00 Sep 14 2005 Page 268 of 982 REJ09B0023 0400...
Страница 454: ...Section 12 Bus State Controller BSC Rev 4 00 Sep 14 2005 Page 404 of 982 REJ09B0023 0400...
Страница 500: ...Section 13 Direct Memory Access Controller DMAC Rev 4 00 Sep 14 2005 Page 450 of 982 REJ09B0023 0400...
Страница 504: ...Section 14 U Memory Rev 4 00 Sep 14 2005 Page 454 of 982 REJ09B0023 0400...
Страница 566: ...Section 17 Compare Match Timer CMT Rev 4 00 Sep 14 2005 Page 516 of 982 REJ09B0023 0400...
Страница 734: ...Section 18 Multi Function Timer Pulse Unit MTU Rev 4 00 Sep 14 2005 Page 684 of 982 REJ09B0023 0400...
Страница 868: ...Section 21 A D Converter Rev 4 00 Sep 14 2005 Page 818 of 982 REJ09B0023 0400...
Страница 914: ...Section 23 I O Ports Rev 4 00 Sep 14 2005 Page 864 of 982 REJ09B0023 0400...
Страница 956: ...Section 24 List of Registers Rev 4 00 Sep 14 2005 Page 906 of 982 REJ09B0023 0400...
Страница 1016: ...Section 25 Electrical Characteristics Rev 4 00 Sep 14 2005 Page 966 of 982 REJ09B0023 0400...
Страница 1024: ...Appendix Rev 4 00 Sep 14 2005 Page 974 of 982 REJ09B0023 0400...
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