HD64F2145 Datasheet, PDF (536/829 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

processing using interrupts. Table 18.5 lists the conditions that set and clear GA20 (P81). Figure
18.2 shows the GA20 output in flowchart form. Table 18.6 indicates the GA20 output signal
values.
Table 18.5 GA20 (P81) Set/Clear Timing
Pin Name
GA20
(P81)
Setting Condition
Rising edge of the host’s write signal
(,2:) when bit 1 of the written data is 1
and the data follows an H'D1 host
command
Clearing Condition
Rising edge of the host’s write signal
(,2:) when bit 1 of the written data is 0
and the data follows an H'D1 host
command
Also, when bit FGA20E in HICR is cleared
to 0
Start
Host write
No
H'D1 command
received?
Yes
Wait for next byte
Host write
No
Data byte?
Yes
Write bit 1 of data byte
to DR bit of P81/GA20
Figure 18.2 GA20 Output
Rev. 2.0, 08/02, page 496 of 788