HT45R35V Holtek Semiconductor Inc., HT45R35V Datasheet - Page 25

• Manufacturer Part Number: HT45R35V
• Description: C/r To F Type 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

Programming Example
The following example shows how the VFD display data is programmed by the microcontroller.
strobe
clk
data
data_2_register:
data_2_register_1:
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~V
will automatically reset the device internally.
The LVR includes the following specifications:
Note:
Rev. 1.00
The low voltage (0.9V~V
nal state for longer than t
does not exceed t
perform a reset function.
The LVR uses an OR function with the external RES
signal to perform a chip reset.
mov
mov
clr
clr
set
snz
clr
rlc
rlc
rlc
set
sdz
jmp
set
ret
LVR
*1: To make sure that the system oscillator has stabilized, the SST provides an extra delay of 1024 system
*2: Since low voltage has to be maintained its original state for longer than t
, such as when changing a battery, the LVR
clock pulses before starting the normal operation.
the reset mode.
equ pb.5
equ pb.6
equ pb.7
a,024d
count,a
strobe
clk
data
vfd_grid.7
data
vfd_segl
vfd_segh
vfd_grid
clk
count
data_2_register_1
strobe
LVR
, the LVR will ignore it and will not
LVR
LVR
) has to remain in its origi-
; send data to vfd driver
; shift register counter
; strobe = 0
; clk = 0
; data = 1
; data = 0
; shift data to vfd[7:0]
; shift data to vfd[15:8]
; shift data to vfd[22:16]
; clk = 1 (rising edge)
; strobe = 1, vfd output
. If the low voltage state
Low Voltage Reset
25
The relationship between V
Note:
V
operation at 4MHz system clock.
OPR
is the voltage range for proper chip
LVR
, therefore a t
DD
and V
LVR
LVR
January 15, 2009
HT45R35V
is shown below.
delay enters