HT86AR72 datasheet(44/68 Pages) HOLTEK

44 / 68 page

HT86Axx/HT86ARxx

Rev. 1.10

December 12, 2012

In the following table, D0~D11 are the A/D conversion

data result bits.

Bit

ADRL

¾¾¾¾

ADRH

D11 D10 D9

A/D Data Register

A/D Converter Control Register

- ADCR

To control the function and operation of the A/D con-

verter, a control register known as ADCR is provided.

This 8-bit register defines functions such as the selec-

tion of which analog channel is connected to the internal

A/D converter, which pins are used as analog inputs and

which are used as normal I/Os as well as controlling the

start function and monitoring the A/D converter end of

conversion status.

One section of this register contains the bits

ACS1~ACS0 which define the channel number. As each

of the devices contains only one actual analog to digital

converter circuit, each of the individual 4 analog inputs

must be routed to the converter. It is the function of the

ACS1~ACS0 bits in the ADCR register to determine

which analog channel is actually connected to the inter-

nal A/D converter.

The ADCR control register also contains the

PCR2~PCR0 bits which determine which pins on Port C

are used as analog inputs for the A/D converter and

which pins are to be used as normal I/O pins. Note that if

the PCR2~PCR0 bits are all set to zero, then all the Port

C pins will be setup as normal I/Os and the internal A/D

converter circuitry will be powered off to reduce the

power consumption.

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 EOC bit in the ADCR register will be set high and the

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

bit that is used to control the overall on/off operation of

the internal analog to digital converter.

The EOC bit in the ADCR register is used to indicate

when the analog to digital conversion process is com-

plete. This bit will be automatically cleared to zero 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 EOC bit in the ADCR register to check whether it

has been cleared as an alternative method of detecting

the end of an A/D conversion cycle.

A/D Converter Clock Source Register

- ACSR

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

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

ratio, the value of which is determined by the ADCS1

and ADCS0 bits in the ACSR register.

Although the A/D clock source is determined by the sys-

tem clock fOSC, and by bits ADCS1 and ADCS0, there

are some limitations on the maximum A/D clock source

speed that can be selected. Refer to the following table.

ACS1

ACS0

Analog Channel

AN0

AN1

AN2

AN3

ACS Table: A/D Channel Select Table

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

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

T h e d e t a i l r e f e r e n c e A C S t a b l e

b 7

b 0

S T A R T

P C R 2 P C R 1 P C R 0

A C S 1 A C S 0

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

T h e d e t a i l r e f e r e n c e P C R t a b l e

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

N o t i m p l e m e n t e d r e a d a s " 0 "

ADCR Register

HT86AR72 Datasheet(PDF) 44 Page - Holtek Semiconductor Inc

HT86AR72 Datasheet(HTML) 44 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 62 63 64 65 66 67 68

Datasheet Download

Link URL