277
Figure 8-28 shows a transfer example in which
TEND
output is enabled and word-size single
address mode transfer (read) is performed from external 8-bit, 2-state access space to an external
device.
DMA read
ø
Address bus
DMA read
DMA read
DMA
dead
RD
TEND
DACK
Bus
release
Bus
release
Bus
release
Bus
release
Last transfer
cycle
Figure 8-28 Example of Single Address Mode (Word Read) Transfer
A one-byte or one-word transfer is performed for one transfer request, and after the transfer the
bus is released. While the bus is released, one or more bus cycles are inserted by the CPU or
DTC.
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.