Datasheet

Section 18 Host Interface
Rev. 4.00 Sep 27, 2006 page 594 of 1130
REJ09B0327-0400
Bit 0—Output Buffer Full (OBF): Set to 1 when the slave processor writes to ODR1. Cleared to
0 when the host processor reads ODR.
Bit 0
OBF Description
0 [Clearing condition]
When the host processor reads ODR or the slave writes 0 in the OBF bit (Initial value)
1 [Setting condition]
When the slave processor writes to ODR
Table 18.3 shows the conditions for setting and clearing the STR flags.
Table 18.3 Set/Clear Timing for STR Flags
Flag Setting Condition Clearing Condition
C/D Rising edge of host’s write signal
(IOW) when HA0 is high
Rising edge of host’s write signal (IOW) when
HA0 is low
IBF
*
Rising edge of host’s write signal
(IOW) when writing to IDR1
Falling edge of slave’s internal read signal (RD)
when reading IDR1
OBF Falling edge of slave’s internal write
signal (WR) when writing to ODR1
Rising edge of host’s read signal (IOR) when
reading ODR1
Note: * The IBF flag setting and clearing conditions are different when the fast A20 gate is
used. For details see table 18.7.