1075
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
41.6.7
DACC Timings
The DACC startup time must be defined by the user in the STARTUP field of the
.
This startup time differs depending of the use of the fast wake-up mode along with sleep mode,
in this case the user must set the STARTUP time corresponding to the fast wake up and not the
standard startup time.
A max speed mode is available by setting the MAXS bit to 1 in the DACC_MR register. Using
this mode, the DAC Controller no longer waits to sample the end of cycle signal coming from the
DACC block to start the next conversion and uses an internal counter instead. This mode gains
2 DACC Clock periods between each consecutive conversion.
Warning: Using this mode, the EOC interrupt of the DACC_IER register should not be used as it
is 2 DACC Clock periods late.
After 20 µs the analog voltage resulting from the converted data will start decreasing, therefore it
is necessary to refresh the channel on a regular basis to prevent this voltage loss. This is the
purpose of the REFRESH field in the DACC Mode Register where the user will define the period
for the analog channels to be refreshed.
Warning: A REFRESH PERIOD field set to 0 will disable the refresh function of the DACC
channels.
Figure 41-2. Conversion Sequence
MCK
Write USER_SEL
field
Selected Channel
Write DACC_CDR
DAC Channel 0
Output
DAC Channel 1
Output
EOC
Read DACC_ISR
Select Channel 0
Channel 0
Channel 1
Data 0
Data 1
Data 2
Data 0
Data 1
Data 2
Select Channel 1
None
TXRDY
CDR FIFO not full
Содержание SAM4S Series
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