HT45R37V datasheet(22/90 Pages) HOLTEK

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HT45R37V

Rev. 1.00

October 20, 2009

· PFD Output

The device contains a PFD function whose single out-

put is pin-shared with I/O pin PA3. The output function

of this pin is chosen via a configuration option and re-

mains fixed after the device is programmed. Note that

the corresponding bit of the port control register,

PAC.3, must setup the pin as an output to enable the

PFD output. If the PAC port control register has setup

the pin as an input, then the pin will function as a nor-

mal logic input with the usual pull-high selection, even

if the PFD configuration option has been selected.

· PWM Outputs

The device contains two PWM outputs shared with

pins PD0 and PD1. The PWM output functions are

chosen via registers. Note that the corresponding bit

of the port control register, PDC, must setup the pin as

an output to enable the PWM output. If the PDC port

control register has setup the pin as an input, then the

pin will function as a normal logic input with the usual

pull-high selection, even if the PWM registers have

enabled the PWM function.

· A/D Inputs

The device contains a multi-channel A/D converter in-

puts. All of these analog inputs are pin-shared with I/O

pins on Port B. If these pins are to be used as A/D in-

puts and not as normal I/O pins then the corresponding

bits in the A/D Converter Control Register, ADCR, must

be properly set. There are no configuration options as-

sociated with the A/D function. If used as I/O pins, then

full pull-high resistor register remain, however if used

as A/D inputs then any pull-high resistor selections as-

sociated with these pins will be automatically discon-

nected.

I/O Pin Structures

The accompanying diagrams illustrate the internal

structures of some I/O pin types. As the exact logical

construction of the I/O pin will differ from these draw-

ings, they are supplied as a guide only to assist with the

functional understanding of the I/O pins. The wide range

of pin-shared structures does not permit all types to be

shown.

Programming Considerations

Within the user program, one of the first things to con-

sider is port initialisation. After a reset, all of the I/O data

and port control registers will be set high. This means

that all I/O pins will default to an input state, the level of

which depends on the other connected circuitry and

whether pull-high selections have been chosen. If the

port control registers, PAC, PBC, PCC and PDC, are

then programmed to setup some pins as outputs, these

output pins will have an initial high output value unless

the associated port data registers, PA, PB, PC and PD,

are first programmed. Selecting which pins are inputs

and which are outputs can be achieved byte-wide by

loading the correct values into the appropriate port con-

trol register or by programming individual bits in the port

control register using the

²SET [m].i² and ²CLR [m].i² in-

structions. Note that when using these bit control in-

structions, a read-modify-write operation takes place.

The microcontroller must first read in the data on the en-

tire port, modify it to the required new bit values and then

rewrite this data back to the output ports.

Port A has the additional capability of providing wake-up

functions. When the device is in the Power Down Mode,

various methods are available to wake the device up.

One of these is a high to low transition of any of the Port

A pins. Single or multiple pins on Port A can be setup to

have this function.

P A P U , P B P U , P C P U , P D P U R e g i s t e r

P A . 0 , P B . 0 , P D . 0 P u l l - h i g h

1 : e n a b l e

0 : d i s a b l e

P A . 1 , P B . 1 , P C . 1 , P D . 1 P u l l - h i g h

1 : e n a b l e

0 : d i s a b l e

P A . 7 , P B . 5 , P C . 4 , P D . 7 P u l l - h i g h

1 : e n a b l e

0 : d i s a b l e

b 7

P X P U 0

b 0

P X P U 1

P X P U 7

Pull-High Resistor Register

- PAPU, PBPU, PCPU, PDPU

T 1

T 2

T 3

T 4

T 1

T 2

T 3

T 4

W r i t e t o P o r t

R e a d f r o m P o r t

S y s t e m C l o c k

P o r t D a t a

Read/Write Timing

HT45R37V Datasheet(PDF) 22 Page - Holtek Semiconductor Inc

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