Section 8 RAM-FIFO Unit (RFU)
Rev. 3.00 Jan 25, 2006 page 188 of 872
REJ09B0286-0300
8.7
RFU Bus Cycle
8.7.1
Clock Division
As this LSI supports medium-speed mode, current consumption can be reduced by dividing the
operating clock of the bus master. On the other hand, high-speed response may be requested of the
RFU, which is one of the bus masters. In particular, if the RFU is used as a slave of a host
interface, such as the USB, transfer data should be supplied with a sufficient transfer rate.
The RFU does not support medium-speed mode. The clock division in the medium-speed mode
should be temporarily suspended to switch the clock to high-speed mode by setting the DTSPEED
bit in SBYCR to 1 during DTC and RFU operations (and during CPU operation when transfer
request is generated).
RFU activation
request
1 state
T1
T1
T1
T1
T2
T2
T2
T2
CPU bus cycle
CPU bus cycle
CPU bus cycle
RFU bus cycle
φ
Bus master clock
RFU activation
request
2 states
T1
T1
T1
T1
T2
T2
T2
T2
CPU bus cycle
CPU bus cycle
CPU bus cycle
RFU bus cycle
φ
Bus master clock
The clock division is restored to high-speed mode from medium-speed mode after high-speed 1- to 2-state clocks
when the RFU activation request is generated.
Figure 8.2 Examples of Temporary Cancellation of Medium-Speed Mode
Содержание H8S/2158
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Страница 440: ...Section 15 Watchdog Timer WDT Rev 3 00 Jan 25 2006 page 386 of 872 REJ09B0286 0300...
Страница 606: ...Section 17 I 2 C Bus Interface IIC Rev 3 00 Jan 25 2006 page 552 of 872 REJ09B0286 0300...
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Страница 744: ...Section 20 Encryption Operation Circuit DES and GF Rev 3 00 Jan 25 2006 page 690 of 872 REJ09B0286 0300...
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Страница 768: ...Section 22 A D Converter Rev 3 00 Jan 25 2006 page 714 of 872 REJ09B0286 0300...
Страница 770: ...Section 23 RAM Rev 3 00 Jan 25 2006 page 716 of 872 REJ09B0286 0300...
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Страница 878: ...Section 28 List of Registers Rev 3 00 Jan 25 2006 page 824 of 872 REJ09B0286 0300...
Страница 926: ...Index Rev 3 00 Jan 25 2006 page 872 of 872 REJ09B0286 0300...