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5 adc pin select register (adcchn) – NEC PD17062 User Manual

Page 236

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236

µ

PD17062

b

3

b

2

b

1

#0

(MSB)

(LSB)

(RF : 21H)

ADCCMP

ADCCH2

ADCCH1

ADCCH0

Selected pin

0

0

0

ADC

0

0

0

1

P1C

3

/ADC

1

0

1

0

P0D

0

/ADC

2

0

1

1

P0D

1

/ADC

3

1

0

0

P0D

2

/ADC

4

1

0

1

P0D

3

/ADC

5

1

1

0

No corresponding pin
(do not set)

1

1

1

19.5 ADC PIN SELECT REGISTER (ADCCHn)

The ADCCHn register selects an A/D converter input pin. It is mapped at the upper 3 bits of the register

file at address 21H. Table 19-2 lists the relationships between the ADCCHn and the actually selected pins.

Table 19-2 ADC Pin Selection

When using P1C

3

/ADC

1

as the A/D converter, specify the P1C as an input port.

The P0D

0

/ADC

2

to P0D

3

/ADC

5

pins are internally equipped with pull-down resistors, but the pull-down

resistors are disconnected when they are selected as the A/D converter.

If P1C and P0D pins selected as the A/D converter are accessed as ports, “0” is read out.