D12320VF25V Datasheet, PDF (193/1146 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
Access Read/
Valid
Size Write Address Strobe
Upper Data Bus
(D15 to D8)
8-bit access Byte
space
Read —
Write —
RD
HWR
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.7.00 Feb. 14, 2007 page 159 of 1108
REJ09B0089-0700