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3 how do i set a conversion time, 4 how do i enable analog pin input – FUJITSU MB91460 SERIES FR60 User Manual

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Chapter 44 A/D Converter

6.Q & A

6.3 How do I set a conversion time?

Use Conversion Time Setting registers ADCT to set.

[bit 15 to 10] CT5-0 (A/D conversion time set)

These bits specify clock division of conversion time.
Setting "000001" means one division (=CLKP).
Do not set these bits "000000".
Initialized these bits to "000100" by reset.
Conversion time = CT value * CLKP cycle * 10 + (4 * CLKP)

Remarks : Do not set conversion time over 500 us.

[bit 9 to 0] ST9-0 (Analog input sampling time set)

These bits specify sampling time of analog input.
Initialized these bits to "0000101100" by reset.

Sampling time = ST value * CLKP cycle

Remarks : Do not set sampling time below 1.2 us when AVCC is below 4.5 V.

Necessary sampling time and ST value are calculated by following.
Necessary sampling time (Tsamp) = (Rext + Rin) * Cin * 7
ST9 to ST0 = Tsamp / CLKP cycle

ST has to be set that sampling time is over Tsamp.
ex. CLKP = 32MHz, AVCC >= 4.5V, Rext = 200K
Tsamp = ( 200 * 103 + 2.52 * 103 ) * 10.7 * 10-12 * 7 = 15.17 [us]
ST = 15.17-6 / 31.25-9 = 485.44
ST has to be set over 486

D

(111100110

B

).

Tsamp is decided by Rext. Thus conversion time should be considered together with Rext.

6.4 How do I enable analog pin input?

Use Port Function register PFR and Extra Port Function register EPFR.

Operation

PFR setting

EPFR setting

To program the AN0 pin as an input

PFR29.0 = ‘1’

EPFR29.0 = ‘0’

To program the AN1 pin as an input

PFR29.1 = ‘1’

EPFR29.1 = ‘0’

To program the AN2 pin as an input

PFR29.2 = ‘1’

EPFR29.2 = ‘0’

To program the AN3 pin as an input

PFR29.3 = ‘1’

EPFR29.3 = ‘0’

To program the AN4 pin as an input

PFR29.4 = ‘1’

EPFR29.4 = ‘0’

To program the AN5 pin as an input

PFR29.5 = ‘1’

EPFR29.5 = ‘0’

To program the AN6 pin as an input

PFR29.6 = ‘1’

EPFR29.6 = ‘0’

To program the AN7 pin as an input

PFR29.7 = ‘1’

EPFR29.7 = ‘0’

To program the AN8 pin as an input

PFR28.0 = ‘1’

EPFR28.0 = ‘0’

To program the AN9 pin as an input

PFR28.1 = ‘1’

EPFR28.1 = ‘0’

To program the AN10 pin as an input

PFR28.2 = ‘1’

EPFR28.2 = ‘0’

To program the AN11 pin as an input

PFR28.3 = ‘1’

EPFR28.3 = ‘0’

To program the AN12 pin as an input

PFR28.4 = ‘1’

EPFR28.4 = ‘0’

To program the AN13 pin as an input

PFR28.5 = ‘1’

EPFR28.5 = ‘0’

To program the AN14 pin as an input (*)

PFR28.6 = ‘1’

EPFR28.6 = ‘0’

To program the AN15 pin as an input (*)

PFR28.7 = ‘1’

EPFR28.7 = ‘0’

To program the AN16 pin as an input

PFR27.0 = ‘1’

EPFR27.0 = ‘1’

To program the AN17 pin as an input

PFR27.1 = ‘1’

EPFR27.1 = ‘1’