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A-D CONVERTER
7902 Group User’s Manual
13-19
13.7 Repeat mode
In the repeat mode, the A-D conversion for an input voltage from one selected analog input pin is performed
repeatedly.
In this mode, no A-D conversion interrupt request occurs. Additionally, the A-D conversion start bit (bit 6 at
address 1E16) remains set to “1” until it is cleared to “0” by software, and the A-D converter repeates its
operation while the A-D conversion start bit = “1.”
13.7.1 Settings for repeat mode
Figure 13.7.1 shows an initial setting example for related registers in the repeat mode.
Fig. 13.7.1 Initial setting example for related registers in repeat mode
A-D control registers 0 and 1
b7
b0
A-D control register 0 (Address 1E16)
01
0
b1 b0
b2
Trigger select bit
0 : Internal trigger
1 : External trigger
A-D conversion start bit
0 : A-D conversion halts.
Analog input pin select bits
A-D conversion frequency (
φAD) select bit 0
See Table 13.2.1.
Repeat mode
b7
A-D control register 1 (Address 1F16)
! : It may be either “0” or “1.”
b0
!
0
Resolution mode select bit
0 : 8-bit resolution mode
1 : 10-bit resolution mode
A-D conversion frequency (
φAD) select bit 1
See Table 13.2.1.
External trigger polarity select bit
0 : Falling edge of pin ADTRG’s input signal
1 : Rising edge of pin ADTRG’s input signal
Note: Writing to the following must be performed during the A-D conversion halts
(berore an trigger is generated).
Each bit of the A-D control register 0 (except bit 6)
Each bit of the A-D control register 1
Set A-D conversion start bit to “1.”
b7
b0
A-D control register 0
(Address 1E16)
A-D conversion start bit
1
Operation starts.
Trigger generated
Input an external trigger to
pin ADTRG (falling edge/
rising edge).
Selecting external trigger
Setting internal trigger
VREF connection select bit
0 : Pin VREF is connected.
0
0 0 0 : AN0 selected
0 0 1 : AN1 selected
0 1 0 : AN2 selected
0 1 1 : AN3 selected
1 0 0 : AN4 selected
1 0 1 : AN5 selected
1 1 0 : AN6 selected
1 1 1 : AN7 selected
Port P7 direction register
b7
b0
Port P7 direction register (Address 1116)
AN0
AN1
AN2
AN3
Clear the bits corresponding to analog input
pins to “0.”
Clear bit 7 to “0” when selecting an external
trigger.
AN4
AN5
AN6
AN7