h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 585

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

17.2.6
STR1 is an 8-bit register that indicates status information during host interface processing. Bits 3,
1, and 0 are read-only bits to both the host and slave processors.
STR1 is initialized to H'00 by a reset and in hardware standby mode.
Bits 7 to 4 and Bit 2—Defined by User (DBU): The user can use these bits as necessary.
Bit 3—Command/Data (C/D D D D ): Receives the HA0 input when the host processor writes to IDR1,
and indicates whether IDR1 contains data or a command.
Bit 1—Input Buffer Full (IBF): Set to 1 when the host processor writes to IDR1. This bit is an
internal interrupt source to the slave processor. IBF is cleared to 0 when the slave processor reads
IDR1.
The IBF flag setting and clearing conditions are different when the fast A20 gate is used. For
details see table 17.8, Fast A20 Gate Output Signals.
Bit 3
C/D D D D
0
1
Bit 1
IBF
0
1
Bit
Initial value
Slave Read/Write
Host Read/Write
Note: * Only 0 can be written, to clear the flag.
Status Register 1 (STR1)
Description
Contents of input data register (IDR1) are data
Contents of input data register (IDR1) are a command
Description
[Clearing condition]
When the slave processor reads IDR1
[Setting condition]
When the host processor writes to IDR1
DBU
R/W
R
7
0
DBU
R/W
R
6
0
DBU
R/W
R
5
0
DBU
R/W
R
4
0
Section 17 Host Interface [H8S/2138 Group]
Rev. 4.00 Jun 06, 2006 page 531 of 1004
C/D
R
R
3
0
DBU
R/W
R
2
0
REJ09B0301-0400
IBF
R
R
1
0
(Initial value)
(Initial value)
R/(W) *
OBF
R
0
0