CHAPTER 3 CPU FUNCTIONS
User’s Manual U13850EJ6V0UD
114
Figure 3-17. External Memory Area (When Expanded to 4 MB)
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Image
On-chip peripheral I/O
Internal RAM
Image
Image
Image
Internal ROM
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xx800000H
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xx0FFFFFH
xx400000H
xx3FFFFFH
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Physical external memory
External memory
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3.4.6 External expansion mode
The V850/SB1 and V850/SB2 allow external devices to be connected to the external memory space by using the
pins of ports 4, 5, 6, and 9. To connect an external device, the port pins must be set in the external expansion mode
by using the memory expansion mode register (MM).
The address bus (A1 to A15) is set to multiplexed output with data bus (D1 to D15), though separate output is also
available by setting the memory address output mode register (MAM) (see the User’s Manual of relevant in-circuit
emulator about debugging when using the separate bus).
Caution
Because the A1 pin and WAIT pin are alternate-function pins, the wait function by the WAIT pin
cannot be used when using a separate bus (programmable wait can be used however).
Similarly, a separate bus cannot be used when the wait function by the WAIT pin is being used.
Because the V850/SB1 and V850/SB2 are fixed to single-chip mode in the normal operation mode, the port
alternate pins become the port mode, thereby the external memory cannot be used. When the external memory is
used (external expansion mode), specify the MM register by the program.