HT46R01A datasheet(24/58 Pages) HOLTEK

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HT46R01A

Rev. 1.10

August 13, 2008

PWM Output Control

The PWM output is pin-shared with the I/O pin PA4. To

operate as a PWM output and not as an I/O pin, the cor-

rect bits must be set in the CTRL0 register. A zero value

must also be written to the corresponding bit in the I/O

port control register PAC.4 to ensure that the PWM out-

put pin is setup as an output. After these two initial steps

have been carried out, and of course after the required

PWM value has been written into the PWM register, writ-

ing a high value to the corresponding bit in the output

data register PA.4 will enable the PWM data to appear

on the pin. Writing a zero value will disable the PWM

output function and force the output low. In this way, the

Port A data output register can be used as an on/off con-

trol for the PWM function. Note that if the CTRL0 register

has selected the PWM function, but a high value has

been written to its corresponding bit in the PAC control

still function as a normal input line, with pull-high resistor

options.

PWM Programming Example

The following sample program shows how the PWM

output is setup and controlled.

mov a,64h

; setup PWM value of 100

; decimal which is 64H

mov pwm,a

set ctrl.5

; select the 7+1 PWM mode

set ctrl.3

; select pin PA4 to have a PWM

; function

clr pac.4

; setup pin PA4 as an output

set pa.4

; PD.0=1; enable the PWM

; output

clr pa.4

; disable the PWM output

- pin

; PD4 forced low

Analog to Digital Converter

The need to interface to real world analog signals is a

common requirement for many electronic systems.

However, to properly process these signals by a

microcontroller, they must first be converted into digital

signals by A/D converters. By integrating the A/D con-

version electronic circuitry into the microcontroller, the

need for external components is reduced significantly

with the corresponding follow-on benefits of lower costs

and reduced component space requirements.

A/D Overview

The device contains a 4-channel analog to digital con-

verter which can directly interface to external analog sig-

nals, such as that from sensors or other control signals

and convert these signals directly into an 8-bit digital

value.

The following diagram shows the overall internal struc-

ture of the A/D converter, together with its associated

registers.

A D C S o u r c e

f S Y S / 2

¸ N

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

A D C

V D D

P A 0 / A N 0

P A 1 / A N 1

P A 2 / A N 2

P A 3 / A N 3

A / D r e f e r e n c e v o l t a g e

A D R

A / D D a t a

R e g i s t e r s

P C R 0 ~ P C R 2

A D C S 0 ~ A D C S 2

S T A R T E O C

A D C R

R e g i s t e r

P i n C o n f i g u r a t i o n

B i t s

C h a n n e l S e l e c t

B i t s

S t a r t a n d E n d o f

C o n v e r s i o n B i t s

C l o c k D i v i d e R a t i o

A/D Converter Structure

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