H8S2164 Datasheet, PDF (161/906 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcomputer H8S Family / H8S/2400 Series

Section 6 Bus Controller (BSC)
6.5.2 Valid Strobes
Table 6.13 shows the data buses used and valid strobes for each access space.
In a read, the RD signal is valid for both 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 6.13 Data Buses Used and Valid Strobes
Area
Access Read/
Valid
Size
Write Address Strobe
Upper Data Bus
(D15 to D8/
AD15 to AD8)
Lower Data
Bus (D7 to
D0/AD7 to
AD0)
8-bit access Byte
space
Read —
Write —
RD
HWR
Valid
Ports or others
Ports or others
8-bit access Byte
space
(in address-
data multiplex
extended
mode)
Read —
Write —
RD
HWR
Ports or others Valid
16-bit access Byte
Read Even
RD
space
Odd
Valid
Invalid
Invalid
Valid
Write Even
HWR
Valid
Undefined
Odd
LWR
Undefined
Valid
Word Read —
RD
Valid
Valid
Write —
HWR, LWR Valid
Valid
[Legend]
Undefined:
Invalid:
Ports or others:
Undefined data is output.
Input state with the input value ignored.
Used as ports or I/O pins for on-chip peripheral modules, and are not used as the
data bus.
Rev. 1.00 Mar. 17, 2008 Page 121 of 862
REJ09B0429-0100