Datasheet

14. A/D Converter
page 196
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0020-2020B90JER
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Item Specification
Function The SCAN1 to SCAN0 bits in the ADCON1 register and ADGSEL1 to
ADGSEL0 bits in the ADCON2 register select pins. Analog voltage applied to
the selected pins is converted one-by-one to a digital code. At this time, the
input voltage of AN0 and AN1 are sampled simultaneously.
A/D Conversion Start Condition When the TRG bit in the ADCON0 register is "0" (software trigger)
Set the ADST bit in the ADCON0 register to “1” (A/D conversion started)
When the TRG bit in the ADCON0 register is "1" (hardware trigger)
The trigger is selected by TRG1 and HPTRG0 bits (See Table 14.1.6.2)
The ADTRG pin input changes state from “H” to “L” after setting the ADST bit
to “1” (A/D conversion started)
Timer B0, B2 or Timer B2 interrupt generation frequency setting counter
underflow after setting the ADST bit to “1” (A/D conversion started)
A/D Conversion Stop Condition A/D conversion completed (If selecting software trigger, the ADST bit is
automatically set to "0".
Set the ADST bit to "0" (A/D conversion halted)
Interrupt Generation Timing A/D conversion completed
Analog Input Pin Select from AN0 to AN1 (2 pins), AN0 to AN3 (4 pins), AN0 to AN5 (6 pins), or
AN0 to AN7 (8 pins)
(1)
Readout of A/D conversion result Readout one of the AN0 to AN7 registers that corresponds to the selected pin
NOTE:
1. AN30 to AN32 can be used in the same way as AN0 to AN7. However, all input pins need to belong to
the same group.
14.1.6 Simultaneous Sample Sweep Mode
In simultaneous sample sweep mode, analog voltages applied to the selected pins are converted one-by-
one to a digital code. At this time, the input voltage of AN0 and AN1 are sampled simultaneously using two
circuits of sample and hold circuit. Table 14.1.6.1 shows the simultaneous sample sweep mode specifica-
tions. Figure 14.1.6.1 shows the operation example in simultaneous sample sweep mode. Figure
14.1.6.2 shows ADCON0 to ADCON2 registers and Figure 14.1.6.3 shows ADTRGCON registers in
simultaneous sample sweep mode. Table 14.1.6.2 shows the trigger select bit setting in simultaneous
sample sweep mode. In simultaneous sample sweep mode, Timer B0 underflow can be selected as a
trigger by combining software trigger, ADTRG trigger, Timer B2 underflow, Timer B2 interrupt generation
frequency setting counter underflow or A/D trigger mode of Timer B.
•Example when selecting AN 0 to AN 3 to analog input pins (SCAN1 to SCAN0=01 2 )
A/D conversion started
A/D interrupt request generated
AN 0
AN 1
AN 2
AN 3
AN 4
AN 5
AN 6
AN 7
A/D pin input voltage
sampling
A/D pin conversion
Figure 14.1.6.1 Operation Example in Simultaneous Sample Sweep Mode
Table 14.1.6.1 Simultaneous Sample Sweep Mode Specifications