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A-D CONVE R T E R
7751 Group User’s Manual
8–4
8.2.1 A-D control register 0
Figure 8.2.2 shows the structure of the A-D control register 0. The A-D operation mode select bits 0 select
the operation mode of the A-D converter. The other bits are described below.
8.2 Block description
Fig. 8.2.2 Structure of A-D control register 0
(1)
Analog input select bits (bits 2 to 0)
These bits are used to select an analog input pin in the one-shot mode and repeat mode. Pins which
are not selected as analog input pins function as programmable I/O ports.
These bits must be set again when the user switches the A-D operation mode to the one-shot mode
or repeat mode after performing the operation in the single sweep mode, repeat sweep mode 0 or
repeat sweep mode 1.
b7
b6
b5
b4
b3
b2
b1
b0
A-D control register 0 (Address 1E
16
)
Bit
A-D conversion frequency
(
φ
AD
) select bit 0
Notes 1:
These bits are ignored in the single sweep and repeat sweep mode 0 and repeat
sweep mode 1. (They may be either “0” or “1.”)
2:
When selecting an external trigger, the AN
7
pin cannot be used as an analog input pin.
3:
Use the A-D operation mode select bit 1 (bit 2 at address 1F
16
) to select either the
repeat sweep mode 0 or repeat sweep mode 1.
4:
Writing to each bit (except bit 6) of the A-D control register 0 must be performed while
the A-D converter halts.
A-D conversion start bit
Trigger select bit
4
A-D operation mode select bits 0
2
1
0
Bit name
At reset
0
Undefined
RW
Functions
0
selected
0 0 1 : AN
1
selected
0 1 0 : AN
2
selected
0 1 1 : AN
3
selected
1 0 0 : AN
4
selected
1 0 1 : AN
5
selected
1 1 0 : AN
6
selected
1 1 1 : AN
7
selected
(Note 2)
b2 b1 b0
0 : Internal trigger
1 : External trigger
0 0 : One-shot mode
0 1 : Repeat mode
1 0 : Single sweep mode
1 1 : Repeat sweep mode 0 /
Repeat sweep mode 1
(Note 3)
0 : Stop A-D conversion
1 : Start A-D conversion
b4 b3
Analog input select bits
(Valid in one-shot and repeat
modes)
(Note 1)
3
7
6
5
Undefined
Undefined
RW
RW
RW
RW
RW
RW
RW
RW
0
0
0
0
Refer to
Table 8.2.1