Table of Contents
Advertisement
When activated by a transfer request, the DMAC executes a burst transfer. During the transfer
MARA and MARB are updated according to the DTCR settings, and ETCRAH is decremented.
When ETCRAH reaches H'00, it is reloaded from ETCRAL to restore the initial value. The
memory address register of the block area is also restored to its initial value, and ETCRB is
decremented. If ETCRB is not H'0000, the DMAC then waits for the next transfer request.
ETCRAH and ETCRAL should be initially set to the same value.
The above operation is repeated until ETCRB reaches H'0000, at which point the DTE bit is
cleared to 0 and the transfer ends. If the DTIE bit is set to 1, a CPU interrupt is requested at this
time.
Figure 7.11 shows examples of a block transfer with byte data size when the block area is the
destination. In (a), the block area address is cycled. In (b), the block area address is held fixed.
Transfers can be requested (activated) by compare match/input capture A interrupts from 16-bit
timer channels 0 to 2, by a conversion-end interrupt from the A/D converter, and by external
request signals.
For the detailed settings see section 7.3.4, Data Transfer Control Registers (DTCR).
219
Advertisement
Table of Contents
