HT66F13 datasheet(117/173 Pages) HOLTEK

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A/D Programming Example

The following two programming examples illustrate how to setup and implement an A/D conversion.

In the first example, the method of polling the EOCB bit in the ADCR0 register is used to detect when

the conversion cycle is complete, whereas in the second example, the A/D interrupt is used to

determine when the conversion is complete.

Example 1: using an EOCB polling method to detect the end of conversion

clr

ADE

; disable ADC interrupt

mov

a,03H

mov

ADCR1,a

; select fSYS/8 as A/D clock and switch off 1.25V

clr

ADOFF

mov

a,0Fh

; setup ACER register to configure pins AN0~AN3

mov

ACER,a

mov

a,00h

mov

ADCR0,a

; enable and connect AN0 channel to A/D converter

start_conversion:

clr

START

; high pulse on start bit to initiate conversion

set

START

; reset A/D

clr

START

; start A/D

polling_EOC:

EOCB

; poll the ADCR0 register EOCB bit to detect end of A/D conversion

jmp

polling_EOC

; continue polling

mov

a,ADRL

; read low byte conversion result value

mov

ADRL_buffer,a

; save result to user defined register

mov

a,ADRH

; read high byte conversion result value

mov

ADRH_buffer,a

; save result to user defined register

jmp

start_conversion

; start next a/d conversion

Rev. 1.10

117

February 9, 2011

HT66F13/HT66F14/HT66F15

Enhanced A/D Flash Type MCU

F F E H

(

)

A / D C o n v e r s i o n

R e s u l t

F F F H

F F D H

0 3 H

0 2 H

0 1 H

0 . 5 L S B

4 0 9 3 4 0 9 4 4 0 9 5 4 0 9 6

A n a l o g I n p u t V o l t a g e

1 . 5 L S B

V D D o r V R E F

4 0 9 6

Ideal A/D Transfer Function

HT66F13 Datasheet(PDF) 117 Page - Holtek Semiconductor Inc

HT66F13 Datasheet(HTML) 117 Page - Holtek Semiconductor Inc

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