BAT32G1x9 user manual | Chapter 24 Enhanced DMA
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Rev.1.02
24.5.4
Response time of the DMA
The DMA response time is shown in Table 24-12. DMA response time is the time from the time when the
DMA initiates the source when the DMA is detected and the DMA transmission begins, excluding the number
of execution clocks for the DMA.
Table 24-12Response times for
DMA
Minimum time
Maximum time
Response time
3 clocks
23 clocks
However, the response of the DMA may also be delayed in the following cases. The number of clocks
delayed varies depending on the condition.
•
Maximum response time in
case of executing
instructions from internal
RAM: 20 clocks
•
Maximum response time for access to timerA
registers in which wait occurs: Maximum
response time + 1 clock for each condition
Note 1
clock:
1/f
CLK
(f
CLK
:
CPU/peripheral hardware clock).
24.5.5
The startup source for the DMA
•
You cannot enter the same startup source between entering the DMA boot source and ending the
DMA transfer.
•The
DMA boot allow bit corresponding to that boot source cannot be manipulated at the location
where the DMA boot source is generated.
•
If the DMA boot source sends a competition, the CPU determines the priority when it accepts the
DMA transfer and decides to start the boot source. For the priority of the startup source, refer to the
"23.3.3 Vector Table".
•If DMA startup is allowed in one of the following states, DMA transmission begins and an interruption
occurs after the transfer ends. Therefore, it is necessary to allow DMA to start after the monitor flag
(CnMON) of the acknowledging comparator.
- Set to generate interrupt requests through the one-edge detection of the comparator
note
(CnEDG=0) and interrupt requests through the rising edge of the comparator (CnEPO=0) and
IVCMP > IVREF (or internal reference voltage of 1.45V).
-
Set to produce an interrupt request through the comparator's one-edge detection
(CnEDG=0and an interrupt request is generated through the falling edge of the comparator
(CnEPO=1AndIVCMP
<
IVREF(Or internal reference voltage.)1.45V)
。
(n=0, 1)