HT45R35V datasheet(25/42 Pages) HOLTEK

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HT45R35V

Rev. 1.00

January 15, 2009

Programming Example

The following example shows how the VFD display data is programmed by the microcontroller.

strobe

equ pb.5

clk

equ pb.6

data

equ pb.7

data_2_register:

; send data to vfd driver

mov

a,024d

; shift register counter

mov

count,a

clr

strobe

; strobe = 0

data_2_register_1:

clr

clk

; clk = 0

set

data

; data = 1

snz

vfd_grid.7

clr

data

; data = 0

rlc

vfd_segl

; shift data to vfd[7:0]

rlc

vfd_segh

; shift data to vfd[15:8]

rlc

vfd_grid

; shift data to vfd[22:16]

set

clk

; clk = 1 (rising edge)

sdz

count

jmp

data_2_register_1

set

strobe

; strobe = 1, vfd output

ret

Low Voltage Reset

- LVR

The microcontroller provides a low voltage reset circuit

in order to monitor the supply voltage of the device. If the

supply voltage of the device is within the range

0.9V~VLVR, such as when changing a battery, the LVR

will automatically reset the device internally.

The LVR includes the following specifications:

· The low voltage (0.9V~V

LVR) has to remain in its origi-

nal state for longer than tLVR. If the low voltage state

does not exceed tLVR, the LVR will ignore it and will not

perform a reset function.

· The LVR uses an

²OR² function with the external RES

signal to perform a chip reset.

The relationship between VDD and VLVR is shown below.

Note:

VOPR is the voltage range for proper chip

operation at 4MHz system clock.

5 . 5 V

3 . 0 V

2 . 2 V

0 . 9 V

V D D

V O P R

V L V R

5 . 5 V

V D D

5 . 5 V

V L V R

0 . 9 V

0 V

R e s e t S i g n a l

R e s e t

* 1

* 2

N o r m a l O p e r a t i o n

R e s e t

L V R D e t e c t V o l t a g e

Low Voltage Reset

Note:

*1: To make sure that the system oscillator has stabilized, the SST provides an extra delay of 1024 system

clock pulses before starting the normal operation.

*2: Since low voltage has to be maintained its original state for longer than tLVR, therefore a tLVR delay enters

the reset mode.

HT45R35V Datasheet(PDF) 25 Page - Holtek Semiconductor Inc

HT45R35V Datasheet(HTML) 25 Page - Holtek Semiconductor Inc

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