HT45R37V datasheet(24/90 Pages) HOLTEK

24 / 90 page

HT45R37V

Rev. 1.00

October 20, 2009

The accompanying table shows the 24-bit shift regis-

ter/latch function truth table:

Clock Strobe Data

VFD0

VFDn

No change No change

VFDn-1

No change No change

Note:

²X² means don¢t care

²VFDn² means VFD1~VFD23

Programming Considerations

After power on all the I/O lines will be automatically

setup as inputs. However as lines PB2~PB5 are used to

drive the VFD interface, they should be setup as outputs

after power is applied to the device. Allowing the VFD in-

terface control lines to be setup as inputs will create an

incorrect VFD display operation. It is advised that the

configuration options select pull-high resistors to be

connected to these lines to keep the lines at a fixed high

level when power is initially applied and until the lines

can be setup as outputs.

Programming Example

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

strobe

equ pb.3

clk

equ pb.4

data

equ pb.5

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

HT45R37V Datasheet(PDF) 24 Page - Holtek Semiconductor Inc

HT45R37V Datasheet(HTML) 24 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 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90

Datasheet Download

Link URL