HT46R49 Holtek Semiconductor, HT46R49 Datasheet - Page 31

• Manufacturer Part Number: HT46R49
• Description: Cost-Effective A/D Type 8-Bit MCU
• Manufacturer: Holtek Semiconductor

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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 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
Start_conversion:
Polling_EOC:
Rev. 1.30
clr EADI
mov a,00000001B
mov ACSR,a
mov a,00100000B
mov ADCR,a
clr START
set START
clr START
sz
jmp polling_EOC
mov a,ADR
mov adr_buffer,a
jmp start_conversion
:
:
:
EOCB
:
:
; disable ADC interrupt
; setup the ACSR register to select f
; the A/D clock
; setup ADCR register to configure Port PB0~PB3
; as A/D inputs
; 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
; reset A/D
; start A/D
; poll the ADCR register EOCB bit to detect end
; of A/D conversion
; continue polling
; read conversion result value from the ADR
; register
; save result to user defined memory
; start next A/D conversion
HT46R46/C46/R47/C47/R48A/C48A/R49
31
SYS
/8 as
June 5, 2008