160
7.4.3
Valid Strobes
Table 7-4 shows the data buses used and valid strobes for the access spaces.
In a read, the
RD
signal is valid without discrimination between the upper and lower halves of the
data bus.
In a write, the
HWR
signal is valid for the upper half of the data bus, and the
LWR
signal for the
lower half.
Table 7-4
Data Buses Used and Valid Strobes
Area
Access
Size
Read/
Write
Address
Valid
Strobe
Upper Data Bus
(D15 to D8)
Lower data bus
(D7 to D0)
8-bit access
Byte
Read
—
RD
Valid
Invalid
space
Write
—
HWR
Hi-Z
16-bit access
Byte
Read
Even
RD
Valid
Invalid
space
Odd
Invalid
Valid
Write
Even
HWR
Valid
Hi-Z
Odd
LWR
Hi-Z
Valid
Word
Read
—
RD
Valid
Valid
Write
—
HWR
,
LWR
Valid
Valid
Note:
Hi-Z: High impedance.
Invalid: Input state; input value is ignored.
Содержание H8S/2645
Страница 4: ......
Страница 16: ......
Страница 58: ...26 ...
Страница 110: ...78 ...
Страница 120: ...88 ...
Страница 132: ...100 ...
Страница 160: ...128 ...
Страница 172: ...140 ...
Страница 235: ...203 Transfer SAR or DAR DAR or SAR Block area First block Nth block Figure 8 8 Memory Mapping in Block Transfer Mode ...
Страница 418: ...386 ...
Страница 444: ...412 ...
Страница 530: ...498 ...
Страница 562: ...530 ...
Страница 642: ...610 ...
Страница 662: ...630 ...
Страница 688: ...656 ...
Страница 756: ...724 ...
Страница 784: ...752 ...
Страница 812: ...780 ...
Страница 837: ...805 A 2 Instruction Codes Table A 2 shows the instruction codes ...
Страница 1152: ...1120 ...