HT48RA0-5 Holtek Semiconductor, HT48RA0-5 Datasheet - Page 15

• Manufacturer Part Number: HT48RA0-5
• Description: Remote Type 8-Bit OTP MCU
• Manufacturer: Holtek Semiconductor

Note:
Rev.1.00
The values of CARH and CARL can be calculated from the following expressions.
D: Carrier duty ratio (0 < D < 1)
f
T: Carrier cycle ( s)
Ensure to input values in the range of 001H to 1FFH to CARL and CARH.
Example:
Carrier output control
The remote controller carrier can be output from the REM/REMDRV pin by clearing to zero bit 9 (CARY) of the
modulo register for setting the high-level period (CARH).
When performing a carrier output, be sure to set the timer operation after setting the CARH (CARH1.0,
CARH0.7~CARH0.0) and CARL (CARL1.0, CARL0.7~CARL0.0) values.
Note that a malfunction may occur if the values of CARH (CARH1.0, CARH0.7~CARH0.0) and CARL (CARL1.0,
CARL0.7~CARL0.0) are changed while the carrier is being output on the REM/REMDRV pin.
Executing the timer manipulation instruction starts the carrier output from the low level.
There is a dual function remote controller carrier output pin named REM/REMDRV. The selection of REM or
REMDRV is determined by a configuration option. The REM pin has a CMOS output structure while the REMDRV pin
has a NMOS open drain output structure. After a reset, the REM carrier output pin will have a low level while the
REMDRV carrier output pin will be in a floating condition. The generic structures of the REM and REMDRV pins are il-
lustrated in the accompanying diagram. As the exact construction of the carrier output pin will differ from these draw-
ings, they are supplied as a guide only to assist with the functional understanding of the remote carrier output pins.
The output from the REM/REMDRV pin is in accordance with the value of bit 9 (CARY) of CARH and the timer output
enable flag (t9), and the value of the timer 9-bit down counter (t0 to t8).
SYS
MOV
MOV
MOV
MOV
CLR
: Input clock (MHz)
CARL (CARL1.0, CARL0.7~CARL0.0) = ( f
CARH (CARH1.0, CARH0.7~CARH0.0) = ( f
f
CARL = (4M
CARH = (4M
SYS
When the carrier signal is active and during the time when the signal is high, if the timer output should go low,
the carrier signal will first complete its high level period before going low.
= 4MHz, fc = 38.1kHz, T = 1/ fc = 26.25 s, duty = 1/3
A,045H
CARL0,A
A,022H
CARH0,A
CARH1.1
(1 1/3)
1/3
26.25 s)
; The carrier is started by clearing CARY(CARH1.1) = 0
26.25 s)
1 = 34 = 22H
Timer Output when Carrier is Output
1 = 69 = 45H
SYS
SYS
(1 D)
D
15
T)
T)
1
1
HT48RA0-5
March 23, 2010
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