HT46R53A datasheet(21/43 Pages) HOLTEK

21 / 43 page

HT46R53A/HT46R54A

Rev. 1.00

August 24, 2006

Example: using Interrupt Method to detect end of conversion

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

clr

ADF

; clear ADC interrupt request flag

set

EADI

; enable ADC interrupt

set

EMI

; enable global interrupt

; ADC interrupt service routine

ADC_ISR:

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,ADRH

; read conversion result high byte value from the ADRH register

mov

adrh_buffer,a

; save result to user defined register

mov

a,ADRL

; read conversion result low byte value from the ADRL register

mov

adrl_buffer,a

; save result to user defined register

clr

START

set

START

; reset A/D

clr

START

; start A/D

EXIT_INT_ISR:

mov

a,status_stack

mov

STATUS,a

; restore STATUS from user defined memory

mov

a,acc_stack

; restore ACC from user defined memory

reti

Low Voltage Reset

- LVR

There is a low voltage reset circuit (LVR) implemented in

the microcontrollers. The function can be enabled/dis-

abled by options.

If the supply voltage of the device is within the range

0.9V~VLVR such as changing a battery, the LVR will au-

tomatically reset the device internally.

The LVR includes the following specifications:

· The low voltage (0.9V~V

LVR) has to remain in their

original state to exceed 1ms. If the low voltage state

does not exceed 1ms, the LVR will ignore it and do not

perform a reset function.

· The LVR uses the

²OR² function with the external RES

signal to perform chip reset.

The relationship between VDD and VLVR is shown below.

Note: VOPR is the voltage range for proper chip

operation at 4MHz system clock.

5 . 5 V

3 . 0 V

2 . 2 V

0 . 9 V

V D D

V O P R

V L V R

5 . 5 V

HT46R53A Datasheet(PDF) 21 Page - Holtek Semiconductor Inc

HT46R53A Datasheet(HTML) 21 Page - Holtek Semiconductor Inc

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