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CHAPTER 18 8-/10-BIT A/D CONVERTER
Table 18.3-5 Function of A/D Setting Register (ADSR0/ADSR1) (1/2)
Bit Name Function
bit15
to
bit13
ST2, ST1, ST0:
Sampling time select
bits
These bits set the sampling time of A/D conversion.
• These bits set the time when the A/D conversion is started and
inputted analog voltage is sampled by the sample & hold circuit
until it is retained.
• See Table 18.3-6 for the setting of these bits.
bit12
to
bit10
CT2, CT1, CT0:
Comparing time
select bits
Comparing time of A/D conversion (comparing time) is set.
• These bits set the time when the analog input is A/D converted until
it stores to the data bits (D9 to D0).
• See Table 18.3-7 for the setting of these bits.
bit9,
bit4 Reserved bits Always write 0 to these bits. Reading value is always 0.
bit8
to
bit5
ANS3 to ANS0:
A/D conversion start
channel select bits
These bits set the channel at which A/D conversion start.At read, the
channel number under conversion can be checked if the A/D
conversion is in progress and last A/D converted channel number can
be checked if the A/D conversion is completed or is stopping.
And before A/D conversion starts, the previous conversion channel
will be read even if these bits have already been set to the new value.
These bits are initialized to "0000B" at reset.
Start channel < end channel:
A/D conversion starts at channel set by A/D conversion start channel
select bits (ANS3 to ANS0) and terminates channel set by A/D
conversion end channel select bits (ANE3 to ANE0)
Start channel = end channel:
A/D conversion is performed only for one channel set by A/D
conversion start (= end) channel select bits (ANS3 to ANS0 = ANE3
to ANE0)
Start channel > end channel:
Do not set
Continuous conversion mode and pause-conversion mode:
When A/D conversion terminated at the channel set by the A/D
conversion end channel select bits (ANE3 to ANE0), it returns to the
channel set by the A/D conversion start channel select bits (ANS3 to
ANS0).
Read (Other than pause-conversion mode) :
The channel numbers (15 to 0) under A/D conversion are read.
Read (Pause-conversion mode) :
At read during a pause, the channel number A/D-converted
immediately before a pause is read.
Notes:
• Do not set the A/D conversion start channel bits (ANS3 to ANS0)
during A/D conversion.
• Access in units of word when writing to these bits. If the byte write
or bit operation is performed, the A/D conversion may be started
from unexpected channel.