D12320VF25IV Datasheet, PDF (204/1304 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 6 Bus Controller
6.4.3 Valid Strobes
Table 6.4 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 6.4 Data Buses Used and Valid Strobes
Area
8-bit access
space
Access
Size
Byte
Read/
Write
Read
Write
Address
—
—
Valid
Strobe
RD
HWR
Upper Data Bus
(D15 to D8)
Valid
16-bit access Byte Read Even
RD
space
Odd
Valid
Invalid
Write Even
HWR
Valid
Odd
LWR
Hi-Z
Word Read —
RD
Valid
Write —
HWR, LWR Valid
Notes: Hi-Z: High impedance
Invalid: Input state; input value is ignored.
Lower Data Bus
(D7 to D0)
Invalid
Hi-Z
Invalid
Valid
Hi-Z
Valid
Valid
Valid
Rev.6.00 Sep. 27, 2007 Page 172 of 1268
REJ09B0220-0600