HT46R92 datasheet(27/61 Pages) HOLTEK

27 / 61 page

HT46R92

Rev. 1.10

November 5, 2008

The START bit in the ADCR register is used to start and

reset the A/D converter. When the microcontroller sets

this bit from low to high and then low again, an analog to

digital conversion cycle will be initiated. When the

START bit is brought from low to high but not low again,

the EOCB bit in the ADCR register will be set to a

²1²

and the analog to digital converter will be reset. It is the

START bit that is used to control the overall on/off opera-

tion of the internal analog to digital converter.

The EOCB bit in the ADCR register is used to indicate

when the analog to digital conversion process is com-

plete. This bit will be automatically set to

²0² by the

microcontroller after a conversion cycle has ended. In

addition, the corresponding A/D interrupt request flag

will be set in the interrupt control register, and if the inter-

rupts are enabled, an appropriate internal interrupt sig-

nal will be generated. This A/D internal interrupt signal

will direct the program flow to the associated A/D inter-

nal interrupt address for processing. If the A/D internal

interrupt is disabled, the microcontroller can be used to

poll the EOCB bit in the ADCR register to check whether

it has been cleared as an alternative method of detect-

ing the end of an A/D conversion cycle.

A/D Converter Power Control

As an integrated circuit function within the device, the

A/D converter will naturally consume a limited amount of

power. However to provide users with a means of on/off

control to reduce power consumption, two methods are

provided. One means of turning off the A/D converter

circuitry is to ensure that the PCR0~PCR2 bits in the

ADCR register are cleared to zero. Another method is to

use the ADONB bit in the ACSR register, which if set

high will also turn off the A/D internal circuitry. Both

power off methods are independent and have overriding

control over the other.

PCR Bits

ADONB Bit

A/D Circuits

Off

> 0

Off

A/D Power Control

It should be noted that the power supply to the A/D con-

verter is supplied via the VDD pin. However the lowest

operating voltage of the analog circuitry is higher than

that of the digital circuitry and therefore the analog cir-

cuits will fail to operate at the lower end of the VDD

specification. The DC Characteristics therefore specify

a separate operating voltage specification for the analog

circuitry.

A/D Converter Clock Source Register

- ACSR

The clock source for the A/D converter, which originates

from the system clock fSYS, is first divided by a division

ratio, the value of which is determined by the ADCS1

and ADCS0 bits in the ACSR register.

b 7

b 0

S T A R T

P C R 2 P C R 1 P C R 0 A C S 2 A C S 1 A C S 0

S e l e c t A / D c h a n n e l

A C S 2

A C S 1

A C S 0

A N 0

A N 1

A N 2

A N 3

A N 4

A N 5

u n d e f i n e d

P o r t B A / D c h a n n e l c o n f i g u r a t i o n s

P C R 2

P C R 1

P C R 0

P o r t B A / D c h a n n e l s - a l l o f f

P B 0 e n a b l e d a s A N 0

P B 0 ~ P B 1 e n a b l e d a s A N 0 ~ A N 1

P B 0 ~ P B 2 e n a b l e d a s A N 0 ~ A N 2

P B 0 ~ P B 3 e n a b l e d a s A N 0 ~ A N 3

P B 0 ~ P B 4 e n a b l e d a s A N 0 ~ A N 4

P B 0 ~ P B 5 e n a b l e d a s A N 0 ~ A N 5

E n d o f A / D c o n v e r s i o n f l a g

1 : n o t e n d o f A / D c o n v e r s i o n - A / D c o n v e r s i o n w a i t i n g o r i n p r o g r e s s

0 : e n d o f A / D c o n v e r s i o n - A / D c o n v e r s i o n e n d e d

S t a r t t h e A / D c o n v e r s i o n

0 ® 1 ® 0 : S t a r t

0 ® 1 : R e s e t A / D c o n v e r t e r a n d s e t E O C B t o " 1 "

E O C B

A D C R R e g i s t e r

A/D Converter Control Register

HT46R92 Datenblatt(PDF) 27 Page - Holtek Semiconductor Inc

HT46R92 Datenblatt(HTML) 27 Page - Holtek Semiconductor Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61

Datenblatt Download

Link URL