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A-D CONVERTER
7902 Group User’s Manual
13-21
13.8 Single sweep mode
In the single sweep mode, the A-D conversions for the input voltages from multiple selected analog input
pins are performed, one at a time. The A-D conversion is performed in ascending sequence from pin AN0
to pin AN7. An A-D conversion interrupt request occurs when the A-D conversions for all selected input pins
are completed.
13.8.1 Settings for single sweep mode
Figure 13.8.1 shows an initial setting example for related registers in the single sweep mode.
When using an interrupt, it is necessary to set the related registers to enable an interrupt. Refer to
“CHAPTER 7. INTERRUPTS” for more details.
Fig. 13.8.1 Initial setting example for related registers in single sweep mode
A-D control registers 0 and 1
b7
b0
A-D control register 0 (Address 1E16)
10
0
Trigger select bit
0 : Internal trigger
1 : External trigger
A-D conversion start bit
0 : A-D conversion halts.
A-D conversion frequency (
φAD) select bit 0
See Table 13.2.1.
Single sweep mode
b7
A-D control register 1 (Address 1F16)
! : It may be either “0” or “1.”
b0
0
Resolution select bit
0 : 8-bit resolution mode
1 : 10-bit resolution mode
A-D sweep pin select bits
0 0 : AN0, AN1 (2 pins)
0 1 : AN0 to AN3 (4 pins)
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
Interrupt priority level
b7
b0
A-D conversion interrupt control register 0
(Address 7016)
Interrupt priority level select bits
Set the level to one of 1 through 7 when using
this interrupt.
Set the level 0 when disabling interrupts.
Interrupt request bit
“0” : No interrupt requested.
0
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
!
1 0 : AN0 to AN5 (6 pins)
1 1 : AN0 to AN7 (8 pins)
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