Operation Of A/D Converter (In One-Shot Mode, An External Trigger Selected) - Renesas M30245 Series User Manual

M30245 Group

2.9.3 Operation of A/D Converter (in one-shot mode, an external trigger selected)

In one-shot mode, choose functions from those listed in Table 2.9.3. Operations of the circled items are
described below. Figure 2.9.6 shows timing chart, and Figure 2.9.7 shows the set-up procedure.
Table 2.9.3. Choosed functions
Item
Operation clock
φ
AD
Resolution
Analog input pin
Trigger for starting
A/D conversion
Sample & Hold
Operation (1) If the level of the AD
the A/D converter begins operating.
(2) After A/D conversion is completed, the content of the successive comparison register (con-
version result) is transmitted to AD register i. At this time, the A/D conversion interrupt re-
quest bit goes to "1". Also the A/D converter stops operating.
(3) If the level of the AD
from step (1) again. If the level of the AD
in progress, the A/D converter stops the A/D conversion in process, and carries out conver-
sion from step (1) again.
φA D
A / D
c o n v e r s i o n
s t a r t f l a g
" H "
A D
T R G
A D r e g i s t e r i
A / D c o n v e r s i o n
i n t e r r u p t r e q u e s t
N o t e : W h e n φ
C o n v e r s i o n r a t e p e r a n a l o g i n p u t p i n i s 4 9 φ
Figure 2.9.6. Operation timing of one-shot mode, with an external trigger selected
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
Set-up
Divided-by-4 f
O
by-3 f / divided-by-2 f
AD
O 8-bit / 10-bit
O One of AN
0
Software trigger
O Trigger by AD
Not activated
O Activated
___________
changes from "H" to "L" with the A/D conversion start flag set to "1",
TRG
___________
pin changes from "H" to "L", the A/D converter carries out conversion
TRG
( 1 ) S t a r t A / D c o n v e r s i o n
8 - b i t r e s o l u t i o n : 2 8 φ
1 0 - b i t r e s o l u t i o n : 3 3 φ
S e t t o " 1 " b y s o f t w a r e
" 1 "
" 0 "
" L "
" 1 "
" 0 "
C l e a r e d t o " 0 " w h e n i n t e r r u p t r e q u e s t i s a c c e p t e d , o r c l e a r e d b y s o f t w a r e
f r e q u e n c y i s l e s s t h a n 1 M H
A D
page 220 of 354
/ divided-
AD
/ f
AD AD
pin to AN pin
7
TRG
___________
pin changes from "H" to "L" while conversion is
TRG
(2) A/D conversion is
c y c l e s
A D
c y c l e s
A D
, s a m p l e a n d h o l d f u n c t i o n c a n n o t b e s e l e c t e d .
Z
c y c l e s f o r 8 - b i t r e s o l u t i o n a n d 5 9 φ
A D
(3) Start A/D
complete conversion
R e s u l t
c y c l e s f o r 1 0 - b i t r e s o l u t i o n .
A D
2. A/D Converter