HD6412350 Hitachi, HD6412350 Datasheet - Page 278

• Manufacturer Part Number: HD6412350
• Description: (HD6412350 / HD6432351) 16-BIT MICROCONTROLLER
• Manufacturer: Hitachi

Full Address Mode (Burst Mode): Figure 7-21 shows a transfer example in which TEND output
is enabled and word-size full address mode transfer (burst mode) is performed from external 16-
bit, 2-state access space to external 16-bit, 2-state access space.
In burst mode, one-byte or one-word transfers are executed consecutively until transfer ends.
In the transfer end cycle (the cycle in which the transfer counter reaches 0), a one-state DMA dead
cycle is inserted after the DMA write cycle.
If a request from another higher-priority channel is generated after burst transfer starts, that
channel has to wait until the burst transfer ends.
If an NMI is generated while a channel designated for burst transfer is in the transfer enabled state,
the DTME bit is cleared and the channel is placed in the transfer disabled state. If burst transfer
has already been activated inside the DMAC, the bus is released on completion of a one-byte or
one-word transfer within the burst transfer, and burst transfer is suspended. If the last transfer
cycle of the burst transfer has already been activated inside the DMAC, execution continues to the
end of the transfer even if the DTME bit is cleared.
258
Address bus
TEND
HWR
Bus release
LWR
RD
ø
Figure 7-21 Example of Full Address Mode (Burst Mode) Transfer
DMA
read
DMA
write
DMA
read
Burst transfer
DMA
write
DMA
read
Last transfer cycle
DMA
write
DMA
dead
Bus release