HT46R46 datasheet(31/77 Pages) HOLTEK

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HT46R46/C46/R47/C47/R48A/C48A/R49

Rev. 1.30

June 5, 2008

A/D Programming Example

The following two programming examples illustrate how to setup and implement an A/D conversion. In the first exam-

ple, the method of polling the EOCB bit in the ADCR 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: using an EOCB polling method to detect the end of conversion for the HT46R46

clr

EADI

; disable ADC interrupt

mov

a,00000001B

mov

ACSR,a

; setup the ACSR register to select fSYS/8 as

; the A/D clock

mov

a,00100000B

; setup ADCR register to configure Port PB0~PB3

; as A/D inputs

mov

ADCR,a

; and select AN0 to be connected to the A/D

; converter

; As the Port B channel bits have changed the

; following START

; signal (0-1-0) must be issued within 10

; instruction cycles

Start_conversion:

clr

START

set

START

; reset A/D

clr

START

; start A/D

Polling_EOC:

EOCB

; poll the ADCR register EOCB bit to detect end

; of A/D conversion

jmp

polling_EOC

; continue polling

mov

a,ADR

; read conversion result value from the ADR

; register

mov

adr_buffer,a

; save result to user defined memory

jmp

start_conversion

; start next A/D conversion

HT46R46 Datasheet(PDF) 31 Page - Holtek Semiconductor Inc

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