M306V2ME Datasheet, PDF (32/276 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER

MITSUBISHI MICROCOMPUTERS
M306V2ME-XXXFP
M306V2EEFP
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
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(5) RDY signal
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RDY signal facilitates access of external devices that require a long time for access. As shown in
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Figure 2.4.6, if an “L” is being input to the RDY pin at the BCLK falling edge, the bus turns to the wait
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state. If an “H” is being input to the RDY pin at the BCLK falling edge, the bus cancels the wait state.
Table 2.4.6 shows the microcomputer state in the wait state. Figure 2.4.6 shows the example of the
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RD signal being extended using the RDY signal.
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The RDY signal is valid when accessing the external area during the bus cycle in which bits 4 to 7 of
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the chip select control register (address 000816) are set to “0.” The RDY signal is invalid when setting
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“1” to all bits 4 to 7 of the chip select control register (address 000816), but the RDY pin should be
treated as properly as in non-using.
Table 2.4.6 Microcomputer status in ready state (Note)
Item
Status
Oscillation
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R/W signal, address bus, data bus, CS
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ALE signal, HLDA, programmable I/O ports
On
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Maintain status when RDY signal received
Internal peripheral circuits
On
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Note: The RDY signal cannot be received immediately prior to a software wait.
In an instance of separate bus
BCLK
RD
CSi
(i=0 to 3)
RDY
tsu(RDY - BCLK)
Accept timing of RDY signal
In an instance of multiplexed bus
BCLK
RD
CSi
(i=0 to 3)
RDY
tsu(RDY - BCLK)
: Wait using RDY signal
: Wait using software
Accept timing of RDY signal
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Figure 2.4.6 Example of RD signal extended by RDY signal
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Rev. 1.0