RF-Star RF-42UP User manual

z
RF-42UP SX1278 433 MHz LoRa Module
Version 1.3
Shenzhen RF-star Technology Co., Ltd.
Jan. 19th, 2020

RF-42UP
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Shenzhen RF-star Technology Co., Ltd. Page 1 of 34
RF-star LoRa Module List
Chipset
Model
Antenna
Dimension
(mm)
Package
Frequency
(MHz)
TX Power
(dBm)
Range
(Km)
Photo
ASR6501
RF-
AL42UH
Half-hole
13.9  13.9
Half-hole
433
22
3
ASR6505
RF-
AL42UHB2
Half-hole
18.3  18.3
Half-hole
433
22
3
SX1278
RF-42UH
Half-hole /
IPEX
16  26
Half-hole
433
18
3/4.5
RF-42UP
SMA
21.1  36
DIP
433
18
3
RF-42SH
Half-hole
16  16
Half-hole
433
18
3
RF-43UH
Half-hole /
IPEX
25  40.3
Half-hole
433
27
10
Contact Me
RF-43UP
SMA
24  43
Half-hole
433
27
10
RF-43SH
Half-hole
25  40
DIP
433
27
10
Contact Me
SX1276
RF-82UH
Half-hole /
IPEX
16  26
Half-hole
868
915
18
3/4.5
RF-82UP
SMA
21.1  36
DIP
868
18
3
RF-82SH
Half-hole
16  16
Half-hole
915
18
3
RF-83UH
Half-hole /
IPEX
25  40.3
Half-hole
868
27
10
Contact Me
RF-83UP
SMA
24  43
DIP
915
27
10
Contact Me
RF-83SH
Half-hole
25  40
Half-hole
868
27
10
Note:
1. The communication distance is the longest distance obtained by testing the module's maximum transmission power
in an open and interference-free environment in sunny weather.
2. Click the picture to jump to buy modules.

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1 Device Overview
1.1 Description
RF-42UP module is a LoRa spread spectrum module, with operating frequency of 410 MHz ~ 525 MHz, based on the
Semtech SX1278. It is a wireless transceiver module with 3.3 V TTL level output. RF-star LoRa module features with
ultra-long range spread spectrum communication, concentrated power density, high interference immunity ability,
confidentiality, and significantly lower current consumption. The communication interface of RF-42UP is UART.
1.2 Key Features
•LoRaTM Modem
•168 dB maximum link budget
•RF output power: +20 dBm
•+14 dBm high efficiency PA
•Programmable bit rate up to 300 kbps
•High sensitivity: down to -148 dBm
•Bullet-proof front end: IIP3 = -11 dBm
•Excellent blocking immunity
•Low RX current of 9.9 mA, 200 nA register retention
•Fully integrated synthesizer with a resolution of 61 Hz
•(G)FSK, (G)MSK, LoRaTM and OOK modulation
•Built-in bit synchronizer of clock recovery
•Preamble detection
•127 dB Dynamic Range RSSI
•Automatic RF Sense and CAD with ultra-fast AFC
•Packet engine up to 256 bytes with CRC
•Built-in temperature sensor and low battery indicator
•Power supply: 3.3 V ~ 5.2 V
•Transmission distance: up to 3000 m
•Compact size: 36.0 mm x 21.1 mm
1.3 Applications
•Automated meter reading
•Home and building automation
•Wireless alarm and security systems
•Industrial monitoring and control
•Long range irrigation system

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1.4 Functional Block Diagram
Figure 1. Functional Block Diagram of RF-42UP
1.5 Part Number Conventions
The part numbers are of the form of RF-42UP where the fields are defined as follows:
Figure 2. Part Number Conventions of RF-42UP
RF
4
Company Name
RF-STAR
-
2
Communication Interface Mode
UART
TX Power
+20 dBm
U
Frequency Range
410 MHz ~ 525 MHz
P
Package Mode
DIP Package
32.0 MHz
MCU
SX1278
SPI
Matching
LPF
Matching
SMA
Connector
LDO
Switching
Low-pass
Filter
Power
Interface
Power Filter

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Table of Contents
RF-star LoRa Module List ............................................................................................................................................... 1
1 Device Overview............................................................................................................................................................. 2
1.1 Description............................................................................................................................................................ 2
1.2 Key Features ....................................................................................................................................................... 2
1.3 Applications .......................................................................................................................................................... 2
1.4 Functional Block Diagram .............................................................................................................................. 3
1.5 Part Number Conventions.............................................................................................................................. 3
Table of Contents................................................................................................................................................................ 4
Table of Figures................................................................................................................................................................... 5
Table of Tables..................................................................................................................................................................... 6
2 Module Configuration and Functions ...................................................................................................................... 7
2.1 Module Parameters........................................................................................................................................... 7
2.2 Module Pin Diagram ......................................................................................................................................... 8
2.3 Pin Functions....................................................................................................................................................... 8
3 Specifications .................................................................................................................................................................10
3.1 Recommended Operating Conditions .....................................................................................................10
3.2 Handling Ratings..............................................................................................................................................10
3.3 Current Consumption .....................................................................................................................................10
4 Application and Layout ...............................................................................................................................................12
4.1 Module Photos..................................................................................................................................................12
4.2 Recommended PCB Footprint....................................................................................................................12
4.3 Schematic Diagram.........................................................................................................................................13
4.4 Reference Design of the Connection between MCU and Module................................................13
5 Module Functions .........................................................................................................................................................14
5.1 Working Mode...................................................................................................................................................14
5.2 Mode Switching (0 for Low Level, 1 for High Level)...........................................................................14
5.3 Normal Mode.....................................................................................................................................................15
5.4 Wake-up Mode..................................................................................................................................................16
5.5 Low-power Mode .............................................................................................................................................16
5.6 Sleep Mode........................................................................................................................................................16

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5.7 Data Security.....................................................................................................................................................17
6 Module Functions .........................................................................................................................................................18
6.1 Transparent Transmission............................................................................................................................18
6.2 Fixed Point Transmission .............................................................................................................................18
6.3 Broadcast and Listening ...............................................................................................................................19
6.4 Module Reset ....................................................................................................................................................19
6.5 EN Function .......................................................................................................................................................20
7 Command Format.........................................................................................................................................................22
7.1 AT Command.....................................................................................................................................................22
7.2 Parameters of Command Setting ..............................................................................................................23
7.2.1 Format.....................................................................................................................................................23
7.2.2 Detailed Parameters..........................................................................................................................23
7.2.3 Examples ...............................................................................................................................................26
8 Implementation ..............................................................................................................................................................29
8.1 Hardware Design .............................................................................................................................................29
8.2 Trouble Shooting..............................................................................................................................................30
8.2.1 Unsatisfactory Transmission Distance........................................................................................30
8.2.2 Vulnerable Module..............................................................................................................................30
8.2.3 High Bit Error Rate .............................................................................................................................30
8.3 Electrostatics Discharge Warnings ...........................................................................................................30
8.4 Soldering and Reflow Condition.................................................................................................................31
8.5 Optional Packaging.........................................................................................................................................32
9 Revision History ............................................................................................................................................................33
10 Contact Us ....................................................................................................................................................................34
Table of Figures
Figure 1. Functional Block Diagram of RF-42UP.......................................................................................... 3
Figure 2. Part Number Conventions of RF-42UP ......................................................................................... 3
Figure 3. Pin Diagram of RF-42UP .................................................................................................................... 8
Figure 4. Photos of RF-42UP .............................................................................................................................12
Figure 5. Recommended PCB Footprint of RF-42UP (mm) ...................................................................12
Figure 6. Schematic Diagram of RF-42UP....................................................................................................13

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Figure 7. Reference Design of the Connection between MCU and Module ....................................13
Figure 8. Transparent Transmission Function Diagram ...........................................................................18
Figure 9. Point Transmission Function Diagram .........................................................................................19
Figure 10. EN Timing Diagram of Wake-up Sleep MCU..........................................................................20
Figure 11. EN Timing Diagram during Sending Data ................................................................................20
Figure 12. EN Timing Diagram during Receiving Data.............................................................................21
Figure 13. EN Timing Diagram during Setting Data...................................................................................21
Figure 14. Recommended Reflow for Lead Free Solder .........................................................................32
Figure 15. Optional Packaging Mode ..............................................................................................................32
Table of Tables
Table 1. Parameters of RF-42UP........................................................................................................................ 7
Table 2. Pin Functions of RF-42UP.................................................................................................................... 8
Table 3. Recommended Operating Conditions of RF-42UP...................................................................10
Table 4. Handling Ratings of RF-42UP...........................................................................................................10
Table 5. Current Consumption of RF-42UP ..................................................................................................10
Table 6. Temperature Table of Soldering and Reflow................................................................................31

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2 Module Configuration and Functions
2.1 Module Parameters
Table 1. Parameters of RF-42UP
Chipset
Semtech SX1278
Supply Power Voltage
3.3 V ~ 5.2 V, recommended to 5.0 V
UART Communication Level
2.5 V ~ 3.6 V, typical: 3.3 V
Frequency
410 MHz ~ 525 MHz, typical: 433 MHz
Transmit Power
+10.0 dBm ~ +20.0 dBm
Receiving Sensitivity
-148 dBm
Number of Channels
116
Default Channel
23 (433 MHz)
Module Address Number
65538 (default as 0)
Crystal
32 MHz
Package
DIP Package
Dimension
36.0 mm x 21.1 mm x (2.5 ± 0.1) mm
Antenna
SMA connector
Operating Humidity
10% RH ~ 90% RH (no condensation)
Storage Humidity
10% RH ~ 90% RH (no condensation)
Operating Temperature
-40 ℃ ～ +85 ℃
Storage Temperature
-45 ℃ ～ +90 ℃
Data Interface Rate @ 3.3 V (TTL)
1200 bps ~ 115200 bps, typical: 9600 bps
Air Rate
0.3 kbps ~ 19.2 kbps (typical: 2.4 kbps)
Single Package Size
196 byte
Cache Size
512 byte
Transmission Distance
3000 m (Test conditions: sunny weather, empty, +20 dBm, antenna gain of
5 dBi, height of above 2.5 m, air speed of 2.4 kbps)
Operating
Current @ 3.3 V
Tx Current
101 mA
Rx Current
15 mA
Sleep Current
3.4 μA

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2.2 Module Pin Diagram
Figure 3. Pin Diagram of RF-42UP
2.3 Pin Functions
Table 2. Pin Functions of RF-42UP
Pin
Name
Pin Type
Description
1
RES_MCU
I
Reset pin, NC.
2
SWIM_MCU
I/O
SWIM pin of internal MCU
3
S0
I
Cooperate with S1 to determine the working mode.
(Cannot be NC, need be grounded if not used.)
4
S1
I
Cooperate with S0 to determine the working mode.
(Cannot be NC, need be grounded if not used.)
5
RXD
I
UART RX signal
6
TXD
O
UART TX signal

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7
EN / AUX
O
Pull the serial port high before sending data and pull low after sending.
Timed wake-up pin, pull high when wake-up.
Pull high when module sending data, pull low after sending.
8
VCC
-
Power supply: 3.3 V ~ 5.2 V.
9
GND
-
Ground, NC.
10
GND
-
Ground, NC.
11
GND
-
Ground, NC.
12
GND
-
Ground, NC.

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3 Specifications
3.1 Recommended Operating Conditions
Functional operation does not guarantee performance beyond the limits of the conditional parameter values in the table
below. Long-term work beyond this limit will affect the reliability of the module more or less.
Table 3. Recommended Operating Conditions of RF-42UP
Items
Condition
Min.
Typ.
Max.
Unit
Operating Supply Voltage
Battery Mode
3.3
5.0
5.2
V
Operating Temperature
/
-40
+25
+85
℃
3.2 Handling Ratings
Table 4. Handling Ratings of RF-42UP
Items
Condition
Min.
Typ.
Max.
Unit
Storage Temperature
Tstg
-45
+25
+90
℃
Human Body Model
HBM, class2
2000
4000
V
Moisture Sensitivity Level
2
Charged Device Model
Class 3
500
1000
V
3.3 Current Consumption
The current consumption characteristics of this module are categorized into different running modes. The overall product
level current consumption is averaged over time on different power modes the device runs on. The peripheral circuitry’s
current consumption also adds in.
Table 5. Current Consumption of RF-42UP
Symbol
Description
Conditions
Min.
Typ.
Max.
Unit
IDDSL
Supply current in Sleep mode
0.2
1
A
IDDIDLE
Supply current in Idle mode
RC oscillator enabled
1.5
A
IDDST
Supply current in Standby mode
Crystal oscillator enabled
1.6
1.8
mA
IDDFS
Supply current in Synthesizer mode
FSRx
5.8
mA
IDDR
Supply current in Receive mode
LnaBoost Off, band 1
10.8
mA
LnaBoost On, band 1
11.5
mA
Bands 2 & 3
12.0
mA

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IDDT
Supply current in Transmit mode with
impedance matching
RFOP = +20 dBm, on
PA_BOOST
120
mA
RFOP = +17 dBm, on
PA_BOOST
87
mA
RFOP = +13 dBm, on
RFO_LF/HF pin
29
mA
RFOP = +7 dBm, on
RFO_LF/HF pin
20
mA

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4 Application and Layout
4.1 Module Photos
Figure 4. Photos of RF-42UP
4.2 Recommended PCB Footprint
Figure 5. Recommended PCB Footprint of RF-42UP (mm)

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4.3 Schematic Diagram
Figure 6. Schematic Diagram of RF-42UP
4.4 Reference Design of the Connection between MCU and Module
Figure 7. Reference Design of the Connection between MCU and Module
Note: TTL level for module and MCU.

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5 Module Functions
5.1 Working Mode
RF-42UP supports 4 kinds of working modes.
Working Mode
S0
S1
Mode Description
Remark
Normal mode
Low level
Low level
Transparent transmission mode.
The receiver must work in
normal mode or wake-up
mode.
Wake-up mode
Low level
High level
Difference from the normal mode:
Before data packet transmission,
automatically add a wake-up code to
wake up the receiver module working
in low-power mode.
The receiver can be in
normal mode, wake-up
mode and low-power mode.
Low-power
mode
High level
Low level
Serial port reception is off, and it is in
the air waiting for wake-up mode.
After receiving wireless data, open the
serial port to send data.
The transmitter must work in
the wake-up mode.
Unable to transmit data in
low-power mode.
Sleep mode
High level
High level
Unable to transmit data, only can
modify and query parameters.
Modify and query settings
and sleep.
Note: Parameters can be modified and queried in all modes. Modification of parameters requires a power-on reset of
the module to take effect. Modifications in sleep mode can be used directly.
5.2 Mode Switching (0 for Low Level, 1 for High Level)
1. Combine high and low levels of S0 and S1 to determine the working mode of the module. Two GPIOs of MCU can
be used to control mode switching. When the level of S0 and S1 are changed, the module is idle for 1 ms, that is,
it starts to work according to the new mode. If the module has serial port data that has not been transmitted by
wireless, it can enter the new working mode after the transmission is completed. If the module receives wireless
data and sends out data through the serial port, it needs to finish sending before entering the new working mod.
Therefore, the mode switching can only be effective when EN outputs 1, otherwise it will delay the switching. For
example: in normal mode or wake-up mode, the user continuously inputs a large amount of data and switches the
mode at the same time. At this time, the mode switching operation is invalid, and the module will process all user
data before performing new mode detection. So, it is generally recommended to detect the output state of the EN
pin and wait for 2 ms after the EN output is high before switching.
2. When the module is switched from other modes to sleep mode, if there is any data that has not been processed

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yet, the module will enter the sleep mode after processing these data (including receiving and sending). This feature
can be used for fast sleep, thus saving power consumption. For example: the transmitter module works in normal
mode, the user initiates serial data "ABC", and then does not have to wait for the EN pin to be idle (high level), and
it can directly switch to sleep mode and the main MCU will immediately sleep. The module will automatically send
all user data by wireless, and then automatically enter sleep within 1 ms, thus saving the working time of MCU and
reducing power consumption.
3. This feature can be used for all mode switching. After processing the current mode event, the module will
automatically enter the new mode within 1 ms, thus eliminating the user's work of querying EN and achieving the
purpose of fast switching. For example: switching from transmit mode to receive mode, the user MCU can also go
to sleep in advance before the mode switching, and use the external interrupt function to get the EN change for
mode switching. This operation method is flexible and efficient, and is designed in accordance with the convenience
of the user MCU, and can reduce the workload of the entire system as much as possible, improve system efficiency,
and reduce power consumption.
5.3 Normal Mode
Type
When S0 = 0 and S1 = 0, the module works in normal mode.
Transmitting
The single packet length of wireless data transmitted by the module is 196 bytes. When the amount
of data input by the user reaches 196 bytes, the module will start wireless transmission. At this time,
the user can continue to input the data to be transmitted. When the byte to be transmitted by the
user is less than 196 bytes, the module waits for 3 bytes. If no user data continues to be input, the
data is considered to be terminated. At this time, the module will send all the data packets by
wireless. When the module receives the first user data, it outputs the EN to the low level, when the
module puts all the data into the RF chip and starts the transmission, the EN outputs to the high
level. At this time, it indicates that the last packet of wireless data has started the transmission, and
the user can continue to input up to 512 bytes of data. The packets sent out through the normal
mode can only be received by the receiving module in normal mode and wake-up mode.
Receiving
The module always turns on the wireless receiving function, and can receive the data packets sent
from the normal mode and wake-up mode. After receiving the data packets, the module EN outputs
the low level and delays for 5 ms, and It starts to send the wireless data through the serial port TXD
pin. After all the wireless data are output through the serial port, the module outputs the EN to the
high level.

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5.4 Wake-up Mode
Type
When S0 = 0 and S1 = 1, the module works in wake-up mode.
Transmitting
The conditions for the module to start packet transmission and the EN function are the same as the
EN function. The only difference is that the module will automatically add a wake-up code before
each packet. The length of the wake-up code depends on the wake-up time set in the user
parameters. The purpose of the wake-up code is to wake up the receiving module working in the
low power consumption mode. Therefore, the data transmitted in the wake-up mode can be used in
the normal mode Module received in wake-up mode and low power consumption mode.
The conditions under which the module initiates a packet transmission and the EN functions are
equivalent to normal mode. The only difference is that the module automatically adds a wake-up
code before each data packet, and the length of the wake-up code depends on the wake-up time
set in the user parameters. The purpose of the wake-up code is to wake up the receiving module
working in the low-power mode. Therefore, the data transmitted in the wake-up mode can be
received by the module in the normal mode, wake-up mode, and low-power mode.
Receiving
Equivalent to normal mode.
5.5 Low-power Mode
Type
When S0 = 1 and S1 = 0, the module works in low-power mode
Transmitting
The module is in sleep state, the serial port is closed, and it cannot receive the serial port data from
the external MCU, so this mode does not have the function of wireless transmission.
Receiving
In the low-power mode, the transmitter is required to work in the wake-up mode. When the wake-
up code is monitored regularly, once the effective wake-up code is received, the module will continue
to be in the receiving state and wait for the whole effective packet to be received. Then the EN
outputs the low Level, after a delay of 5 ms, open the serial port to send the wireless data received
through TXD, and the EN outputs the high when finished. The wireless module continues to enter
the "sleep-monitor" working state, by setting different wake-up time, the module has different receive
response delay (maximum 2 s) and average power consumption (minimum 30 A).
5.6 Sleep Mode
Type
When S0 = 1 and S1 = 1, the module works in sleep mode
Transmitting
Unable to transmit.
Receiving
Unable to receive.

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Configuration
The sleep mode can be used for module parameter setting. Use serial ports 9600 and 8N1 to set
the module working parameters through a specific instruction format, as shown in the following
instruction format details. When entering other modes from sleep mode, the module will re-configure
the parameters. During the configuration, EN remains low. After completion, the module outputs
high level, so it is recommended that users detect the rising edge of EN.
5.7 Data Security
The specific encryption algorithm is used to encrypt the module data. After receiving the data, the receiving module can
get the actual transmission data according to the encryption factor to avoid receiving the wrong information.

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6 Module Functions
6.1 Transparent Transmission
The transparent data transmission under the same channel, the same module address and the same airspeed is shown
in the figure below.
Figure 8. Transparent Transmission Function Diagram
6.2 Fixed Point Transmission
The transparent data transmission under the different channel, the different module address and the different airspeed
is shown in the figure below.

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Figure 9. Point Transmission Function Diagram
6.3 Broadcast and Listening
Input the broadcast address FF FF, the channel XX, and the data to be transmitted in proper order, and then send. All
modules on channel XX within the range of the wireless signal can receive the broadcast data, that is, co-channel
broadcast. However, the address and channel of the sending module can be arbitrary and are not required. The
requirement is to input the broadcast address and destination channel.
Listening and broadcasting are exactly the opposite. Listening is passive. Set the address of the module itself to FF FF,
and the module can receive the data sent by all modules on channel XX.
Note: Broadcast address and listening address are only FF FF.
6.4 Module Reset
After the module is powered on, EN will output low level immediately, carry out hardware self-check, and set the working
mode according to the user parameters. In this process, the EN keeps the low level, and after that, the EN outputs the
high level, and starts to work normally according to the working mode composed of S1 and S0. Therefore, the user
needs to wait for the EN rising edge as the starting point for the normal operation of the module.