CHAPTER 6 DMA FUNCTIONS (DMA CONTROLLER)
User’s Manual U12688EJ4V0UM00
189
6.7
Transfer Objects
6.7.1 Transfer type and transfer objects
Table 6-1 lists the relationship between transfer type and transfer object.
Cautions 1. Among the transfer destinations and sources shown in Table 6-1, when an “
××××
” is indicated
for a combination, that operation is not guaranteed.
2. Make the data bus width of the transfer destination and source the same (for two-cycle
transfer and flyby transfer).
Table 6-1. Relationship Between Transfer Type and Transfer Object
(a) Two-cycle transfer
(b) Flyby transfer
Remark
{
: Possible
×
: Impossible
6.7.2 External bus cycle during DMA transfer
The external bus cycle during DMA transfer is as follows.
Table 6-2. External Bus Cycle During DMA Transfer
Transfer Type
Transfer Object
External Bus Cycle
Internal peripheral I/O, Internal
RAM
None
Note
External I/O
Yes
SRAM cycle
Two-cycle transfer
External memory
Yes
Memory access cycle set in the BCT register
Between internal RAM and
internal peripheral I/O
None
Note
Flyby transfer
Between external memory and
external I/O
Yes
The memory access DMA flyby transfer cycle
set by the BCT register as external memory
Note Other external bus cycles, such as a CPU-based bus cycle, can be started.
Destination
Internal
peripheral
I/O
External
I/O
Internal
RAM
External
memory
Internal
peripheral I/O
×
×
{
×
External I/O
×
×
×
{
Internal RAM
{
×
×
×
External
memory
×
{
×
×
Destination
Internal
peripheral
I/O
External
I/O
Internal
RAM
External
memory
Internal
peripheral I/O
×
×
{
{
External I/O
×
×
{
{
Internal RAM
{
{
{
{
External
memory
{
{
{
{
S
ourc
e
S
ourc
e
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