HT46R006 datasheet(51/72 Pages) HOLTEK

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HT48R006/HT46R006

Rev. 1.00

October 24, 2011

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

clr

ADI

; disable ADC interrupt

mov

a,00000001B

mov

ACSR,a

; select fSYS/8 as A/D clock and ADONB=0

mov

a,00100000B

; setup ADCR register to configure Port as A/D inputs

mov

ADCR,a

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

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,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

Note: To power off ADC module, it is necessary to set ADONB as

²1².

Example: using the interrupt method to detect the end of conversion

clr

ADI

; disable ADC interrupt

mov

a,00000001B

mov

ACSR,a

; select fSYS/8 as A/D clock and ADONB=0

mov

a,00100000B

; setup ADCR register to configure Port as A/D inputs

mov

ADCR,a

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

Start_conversion:

clr

START

set

START

; reset A/D

clr

START

; start A/D

clr

ADF

; clear ADC interrupt request flag

set

ADI

; enable ADC interrupt

set

EMI

; enable global interrupt

; ADC interrupt service routine

ADC_:

mov

acc_stack,a

; save ACC to user defined memory

mov

a,STATUS

mov

status_stack,a

; save STATUS to user defined memory

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

EXIT_ISR:

mov

a,status_stack

mov

STATUS,a

; restore STATUS from user defined memory

mov

a,acc_stack

; restore ACC from user defined memory

clr

ADF

; clear ADC interrupt flag

reti

Note: To power off ADC module, it is necessary to set ADONB as

²1².

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