HT66F03T3/68F03T3 MCU with 315MHz/433MHz ASK Transmitter
1
HT66F03T3/68F03T3 MCU with
315MHz/433MHz ASK Transmitter
D/N：AN0220E
General Description
The HT66F03T3/68F03T3 is a Flash type MCU with an RF ASK transmitter function. Data
generated from the MCU will be transmitted at a carrier frequency of 315M/433MHz to a
receiver.
Functions
Complete UHF transmitter
Frequency range of 300MHz to 450MHz
Output power up to 10dBm
Low external part count with minimal external components
Low voltage operation (down to 2.2V)
Diagram
Hardware Diagram Description
Output matching circuit: the following example uses a low pass matching circuit.
KEY PAD: the following example uses PA0~PA3 and PA6~PA7 as switch input pins.
HT66F03T3/68F03T3 MCU with 315MHz/433MHz ASK Transmitter
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Application Circuit
The circuit in the frame is the harmonic inhibiting enhancement circuit which can be
ignored if not necessary.
Note: The value in the parentheses is for 433MHz. For example, 433.92MHz the Crystal
Y1 should be 13.56MHz.
Adjust Output Power with External Resistors
R1 in the application circuit is used to adjust the RF output power. In this example, the R1
resistor values for the 50 demo board and corresponding typical values of conducted
RF output levels are listed in the table below. R1 in the HT46/48R01T3 demo board uses
a dipole antenna which can be adjusted to an appropriate radiation to meet the
specifications of the design.
Typical ID of PA (mA) Output Power
(dBm) R1() 433MHz 315MHz
10 0 7.8 8.8
3 390 5.0 5.0
0 560 4.0 4.0
HT66F03T3/68F03T3 MCU with 315MHz/433MHz ASK Transmitter
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Reference Clock (CREF ) Example
The Clock CREF is provided for IRC frequency calibration of the MCU. It is useful for
devices that require accurate frequencies, such as RTC applications. The following
example demonstrates an RF transmission from PA4 with data received on PA5 and
calibrated by CREF.
;; PA4 is the toggle output pin
;; PA5 is the cref intput pin
;; tmr0 is used to counte cref
;; tmr1 is used to generate toggle
#INCLUDE HT48R01B.INC
CREF_DEMO .section 'data'
CA1_TMP DB 1
CA2_TMP DB 1
GEN1_TMR_TMP DB 1
GEN2_TMR_TMP DB 1
PA5_TMP DB 1
CREF_COUNT DB 1
CREF_DEMO .section at 0 'code'
ORG 00H
JMP MAIN
ORG 08H
JMP TMR0INT
org 0ch
JMP TMR1INT
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
;~~~~~~~~~~timer0 int
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TMR0INT:
SDZ CA1_TMP
JMP POLLIN_PA5
INC CA2_TMP
POLLIN_PA5:
SZ PA5_TMP
JMP HI
LO:
SNZ PA5 ;POLLING PA5 STATUS
JMP NO_CHANGE
SET PA5_TMP
JMP INC_CREF_COUNT
HI:
SZ PA5 ;POLLING PA5 STATUS
JMP NO_CHANGE
CLR PA5_TMP
JMP INC_CREF_COUNT
INC_CREF_COUNT:
SDZ CREF_COUNT
JMP EXIT
CLR ACC
SUBM A,CA1_TMP
HT66F03T3/68F03T3 MCU with 315MHz/433MHz ASK Transmitter
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CLR tmr0c.4
JMP EXIT
EXIT:
NO_CHANGE:
RETI
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
;~~~~~~~~~~timer1 int
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TMR1INT:
SDZ CREF_COUNT
RETI
SZ PA4 ;TOGGLE PA4
JMP CLR_PA4
SET PA4
JMP $+2
CLR_PA4:
CLR PA4
MOV A,GEN1_TMR_TMP
MOV CREF_COUNT,A
reti
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
;~~~~~~~~~~MAIN
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
MAIN:
;INITIAL I/O
CLR PBC1 ;INITIAL PA4 INTO OUTPUT MODE(dout)
SET PBC0 ;INITIAL PA4 INTO INPUT MODE (cref)
;INITIAL COUNT
CLR PA5_TMP
MOV A,32
MOV CREF_COUNT,A
CLR CA1_TMP
CLR CA2_TMP
;INITIAL TIMER0
mov a,05h ;; enable interupt
mov intc0,a
mov a,82h ;; tmr internal mode
mov tmr0c,a
mov a,236 ;; time base is (256-216)*1us=40us
mov tmr0,a
;INITIAL TIMER1
set et1i ;; enable interupt
mov a,236 ;; time base is (256-216)*1us=40us
mov tmr1,a
mov a,80h ;; tmr internal mode
mov tmr1c,a
SNZ PA5
JMP $-1
SZ PA5
JMP $-1
set tmr0c.4 ;; start tmr
sz CREF_COUNT ;;WAIT COUNTER FINISH
JMP $-1
CLR ET0I ;;Disable the timer 0 interrupt
RLC CA1_TMP ;both ca1_tmp and ca2_tmp are store
HT66F03T3/68F03T3 MCU with 315MHz/433MHz ASK Transmitter
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RLC CA2_TMP ;count value of one cycle * 32 ,so
RLC CA1_TMP ;one cycle is CA1_TMP Divided by 32
RLC CA2_TMP ;
RLC CA1_TMP ;
RLC CA2_TMP ;divide 32
;generate one 2.5ms cycle wave
;20us*CA2_TMP=5ms (1/200=5ms)
;tmr1 2.5ms=> 100us*CA2_TMP*2.5/5
;so tmr1= CA2_TMP/2
CLR C
RRC CA2_TMP
RRC CA1_TMP
MOV A,CA1_TMP ;load counter value
MOV GEN1_TMR_TMP,A
MOV A,CA2_TMP
MOV GEN1_TMR_TMP,A
set tmr1c.4 ;; start tmr1 to generate
JMP $
END
Layout Notes
Component Placement
The first consideration for component placement are their signal lines which must be as
short as possible.
In addition to the antenna matching components, the RF PAOUT pin area should avoid
being occupied with components which may influence proper RF operation.
Routing
As right angles more easily accumulate charge, they will have larger discharges which
will influence PCB stability. It is recommended to conduct all routing using 45 degree
bevels or curves.
The distance between tracks should not be less than 6 mils.
The distance between the wires and the apertures should not be less than 6 mils.
The distance between two linked apertures should not be less than 6 mils.
The width of the VCC and GND tracks should not be less than 12 mils.
Each IC power source must have a decoupling capacitor located adjacent to the IC.
The power supply of the RF and the MCU should be independent so as to avoid
interference.
The RF antenna trace should not have a ground plane so as not to affect performance,
as shown in the figure.
Antenna
A typical application is shown in the figure below.
A market available 50 SMA plug dipole patch antenna
λ/4 length of copper wire, single-core wire, twisted wire
Cost Down applications
RF antenna Trace width=35mil，FR4 PCB material of 1mm thickness
HT66F03T3/68F03T3 MCU with 315MHz/433MHz ASK Transmitter
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Tool Notes
Use the Flash MCU ICE M1001A + D1006A, and select the CFG in the HT68F03 or
HT66F03 to develop the program.
If RF simulation is also required, connect the Holtek 315MHz/433MHz ASK Tx RF Module
to the ICE.
Execute write operations using the e-Writer with Adapter CADP16NSOP-S and
Hope3000 software.
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Holtek HT66F03T3 Quick start guide
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