Hardware, Function block operations, 7) operation description – Renesas 4514 User Manual
Page 56
4513/4514 Group User’s Manual
HARDWARE
1-43
FUNCTION BLOCK OPERATIONS
Table 16 Change of successive comparison register AD during A-D conversion
Comparison voltage (V
ref
) value
Change of successive comparison register AD
At starting conversion
±
±
±
±
±
(7) Operation description
A-D conversion is started with the A-D conversion start instruction
(ADST). The internal operation during A-D conversion is as follows:
➀
When A-D conversion starts, the register AD is cleared to
“000
16
.”
➁
Next, the topmost bit of the register AD is set to “1,” and the
comparison voltage V
ref
is compared with the analog input volt-
age V
IN
.
➂
When the comparison result is V
ref
< V
IN
, the topmost bit of the
register AD remains set to “1.” When the comparison result is
V
ref
> V
IN
, it is cleared to “0.”
The 4513/4514 Group repeats this operation to the lowermost bit of
the register AD to convert an analog value to a digital value. A-D
conversion stops after 62 machine cycles (46.5
µ
s when f(X
IN
) =
4.0 MHz in high-speed mode) from the start, and the conversion re-
sult is stored in the register AD. An A-D interrupt activated condition
is satisfied and the ADF flag is set to “1” as soon as A-D conversion
completes (Figure 27).
✼
1: 1st comparison result
✼
3: 3rd comparison result
✼
9: 9th comparison result
✼
2: 2nd comparison result
✼
8: 8th comparison result
✼
A: 10th comparison result
1st comparison
2nd comparison
3rd comparison
After 10th comparison
completes
1
✼
1
✼
1
✼
1
-----
-----
-----
-----
0
1
✼
2
✼
2
0
0
1
✼
3
0
0
0
✼
8
0
0
0
✼
9
0
0
0
✼
A
A-D conversion result
V
DD
2
V
DD
2
V
DD
2
V
DD
2
V
DD
4
V
DD
4
V
DD
8
V
DD
1024
○
○
○
○
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