483
Status Flag Clearing Timing: After a status flag is read as 1 by the CPU, it is cleared by writing
0 to it. When the DTC or DMAC is activated, the flag is cleared automatically. Figure 11-46
shows the timing for status flag clearing by the CPU, and figure 11-47 shows the timing for status
flag clearing by the DTC or DMAC.
Status flag
Write signal
Address
ø
TSR address
Interrupt
request
signal
TSR write cycle
T1
T2
Figure 11-46 Timing for Status Flag Clearing by CPU
Interrupt
request
signal
Status flag
Address
ø
Source address
DTC/DMAC
read cycle
T1
T2
Destination
address
T1
T2
DTC/DMAC
write cycle
Figure 11-47 Timing for Status Flag Clearing by DTC or DMAC Activation