HT56R656 datasheet(30/108 Pages) HOLTEK

30 / 108 page

HT56R62/HT56R65

HT56R642/HT56R644/HT56R654/HT56R656

Rev. 1.00

July 20, 2009

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 and PDC, are then pro-

grammed to setup some pins as outputs, these output

pins will have an initial high output value unless the as-

sociated port data registers, PA, PB 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 control register

or by programming individual bits in the port control reg-

ister using the

²SET [m].i² and ²CLR [m].i² instructions.

Note that when using these bit control instructions, a

read-modify-write operation takes place. The

microcontroller must first read in the data on the entire

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

write 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.

LCD and LED Driver

For large volume applications, which incorporate an

LCD in their design, the use of a custom display rather

than a more expensive character based display reduces

costs significantly. However, the corresponding COM

and SEG signals required, which vary in both amplitude

and time, to drive such a custom display require many

special considerations for proper LCD operation to oc-

cur. These devices all contain an LCD Driver function,

which with their internal LCD signal generating circuitry

and various options, will automatically generate these

time and amplitude varying signals to provide a means

of direct driving and easy interfacing to a range of cus-

tom LCDs.

Additionally some of the devices also include LED driver

circuitry which can generated the required signals to

drive the COM and SEGMENT signals for LED panels.

All device include a wide range of options to enable LCD

and LED displays of various types to be driven. The ta-

ble shows the range of options available across the de-

vice range.

Part No.

Duty

Driver

No.

Bias

Type

Wave

Type

HT56R62

1/2

´2

1/2

1/3

´3

1/4

´4

HT56R65

1/2

´2

1/3

´3

1/4

´4

HT56R642

1/8

´8

1/3,

1/4

1/5

1/16

´16

HT56R644

HT56R654

1/8

´8

1/16

´16

HT56R656

1/8

´8

1/16

´16

LCD Selections

Note:

1. The HT56R62 and HT56R65 52-pin

packages only have R-bias type.

2. The HT56R62 and HT56R65 devices do not

have an LED driver function.

Device

LED Duty

LED Driver No.

HT56R642

Static

´1

1/4

´4

1/8

´8

1/12

´12

1/16

´16

HT56R644

HT56R654

Static

´1

1/4

´4

1/8

´8

1/12

´12

1/16

´16

HT56R656

Static

´1

1/4

´4

1/8

´8

1/12

´12

1/16

´16

LED Selections

Note:

The HT56R62 and HT56R65 devices do not

have an LED driver function.

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

HT56R656 Datasheet(PDF) 30 Page - Holtek Semiconductor Inc

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