A-D Converter
M30240 Group
Rev.1.00 Sep 24, 2003 Page 235 of 360
2.6.2.2 One-shot mode, external trigger selected
In one-shot mode, select functions from those listed in Table 2.28 . An example using the indicated
options is described below. Figure 2.81 shows the timing chart, and Figure 2.82 shows the set-up
procedure.
Table 2.28: A-D converter in one-shot mode (with an external trigger selected) functions
Operation
(1) If the level of the AD
TRG changes from “H” to “L” with the A-D conversion start flag set to “1”, the
A-D converter begins operating.
(2) After A-D conversion is completed, the content of the successive comparison register (conversion
result) is transmitted to A-D register i. At this time, the A-D conversion interrupt request bit goes to “1”.
Also the A-D converter stops operating.
(3) If the level of the AD
TRG pin changes from “H” to “L”, the A-D converter carries out conversion from
step (1) again. If the level of the AD
TRG pin changes from “H” to “L” while conversion is in progress,
the A-D converter stops the A-D conversion in process, and carries out the conversion from step (1)
again.
Figure 2.81: Operation timing of one-shot mode with an external trigger selected
Item
Set-up Item Set-up
Operation clock ΦAD O
Divided-by-4 fAD/ divided-by-2
fAD/fAD
Trigger for starting A-D
conversion
Software trigger
Resolution O 8-bit / 10-bit O Trigger by AD
TRG
Analog input pin O
One of AN
0
pin to AN
7
pin
Sample & Hold
Not activated
O Activated
A-D
conversion
start flag
“1”
“0”
A-D conversion
interrupt request
AD
TRG
A-D register i
“H”
“L”
“1”
“0”
Cleared to “0” when interrupt request is accepted, or cleared by software
Result
φAD
Set to “1” by software
8-bit resolution : 28 φAD cycles
10-bit resolution : 33 φ
AD cycles
(1) Start A-D conversion (2) A-D conversion is
complete
(3) Start A-D
conversion
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