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8XC196NP, 80C196NU USER’S MANUAL
13-34
Figure 13-17. Write-control Signal Waveforms
Table 13-14 compares the values of the write-control signals for write operations in the standard
mode and the write strobe mode. The table lists values of WR# and BHE# and values of WRL#
and WRH# for 8-bit and 16-bit writes on an 8-bit and 16-bit bus.
To select the standard write-control mode, set CCR0.2. In standard mode, the WR#/WRL# pin
operates as WR#, and the BHE#/WRH# pin operates as BHE#. WR# is asserted for every external
memory write. BHE# is asserted for word accesses (read and write) and for byte accesses to odd
addresses. BHE# can be used to select the bank of memory that stores the high (odd) byte. Figure
13-10 on page 13-22 illustrates use of the standard mode in a 16-bit system. In this example, WR#
writes words to the 16-bit flash memory. To write individual bytes, you can use the decoding logic
in Figure 13-18 or use the write strobe mode.
Table 13-14. Write Signals for Standard and Write Strobe Modes
Bus
Width
Word/Byte
Written
A0
Standard
(CCR0.2 = 1)
Write Strobe
(CCR0.2 = 0)
WR#
BHE#
WRL#
WRH#
8
Low Byte
0
0
1
0
0
High Byte
1
0
0
0
0
Word
0
0
0
0
0
1
Illegal
Illegal
16
Low Byte
0
0
1
0
1
High Byte
1
0
0
1
0
Word
0
0
0
0
0
1
Illegal
Illegal
A2472-02
ALE
WR#
BHE#
ALE
WRL#
WRH#
Standard Mode
Write Strobe Mode
Active for low- or high-byte write.
Active for low-byte write.
Active for high-byte write.
Active for high-byte write.
Содержание 80C196NU
Страница 1: ...8XC196NP 80C196NU Microcontroller User s Manual...
Страница 2: ...8XC196NP 80C196NU Microcontroller User s Manual August 1995 Order Number 272479 002...
Страница 18: ...1 Guide to This Manual...
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Страница 31: ......
Страница 32: ...2 Architectural Overview...
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Страница 48: ...3 Advanced Math Features...
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Страница 56: ...4 Programming Considerations...
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Страница 72: ...5 Memory Partitions...
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Страница 106: ...6 Standard and PTS Interrupts...
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Страница 144: ...7 I O Ports...
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Страница 166: ...8 Serial I O SIO Port...
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Страница 184: ...9 Pulse width Modulator...
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Страница 196: ...10 Event Processor Array EPA...
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Страница 226: ...11 Minimum Hardware Considerations...
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Страница 240: ...12 Special Operating Modes...
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Страница 256: ...13 Interfacing with External Memory...
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Страница 304: ...A Instruction Set Reference...
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Страница 374: ...B Signal Descriptions...
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Страница 390: ...C Registers...
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Страница 448: ...Glossary...
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Страница 458: ...Index...
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