RF-42UH SX1278 433 MHz LoRa Module · 2020. 8. 28. · RF-42UH SX1278 433 MHz LoRa Module Version 1.3 Shenzhen RF-star Technology Co., Ltd. Jan. 19th, 2020

RF-42UH SX1278 433 MHz LoRa Module

Version 1.3

Shenzhen RF-star Technology Co., Ltd.

Jan. 19th, 2020

RF-42UH

www.szrfstar.com V1.3 - Jan., 2020

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-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


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.

http://www.szrfstar.com/https://www.alibaba.com/product-detail/RF-star-433MHz-LoraWAN-LinkWAN-UART_1600103616154.html?spm=a2747.manage.0.0.1c7171d2j4q4cVhttps://www.alibaba.com/product-detail/RF-star-ASR6505-433MHz-LoraWAN-LinkWAN_62502605557.html?spm=a2747.manage.0.0.5bc271d2cEMsVfhttps://www.alibaba.com/product-detail/Low-power-consumption-3000-meters-SX1278_62083932582.html?spm=a2747.manage.0.0.5bc271d2cEMsVfhttps://www.alibaba.com/product-detail/3000-meters-transmission-distance-SX1278-433MHz_62096776878.html?spm=a2747.manage.0.0.26dc71d285OxZPhttps://www.alibaba.com/product-detail/RF-star-ASR6501-433MHz-UART-Lora_62502967492.html?spm=a2747.manage.0.0.26dc71d285OxZPhttps://www.alibaba.com/product-detail/sx1276-915mhz-lora-module-RF-93UH_62100403512.html?spm=a2747.manage.0.0.26dc71d285OxZPhttps://www.alibaba.com/product-detail/Low-Power-High-Sensitivity-SX1276-862MHz_62099683304.html?spm=a2747.manage.0.0.26dc71d285OxZPhttps://www.alibaba.com/product-detail/Long-range-RF-module-Iot-915mhz_62101445001.html?spm=a2747.manage.0.0.26dc71d285OxZPhttps://www.alibaba.com/product-detail/Long-Range-RF-Module-Wireless-Transmitter_62101574820.html?spm=a2747.manage.0.0.26dc71d285OxZPhttps://www.alibaba.com/product-detail/8000-meters-long-distance-433MHz-410MHz_1600103549782.html?spm=a2747.manage.0.0.5bc271d2cEMsVf

RF-42UH



1 Device Overview

1.1 Description

RF-42UH 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-42UH 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: 26.0 mm x 16.0 mm

1.3 Applications

• Automated meter reading

• Home and building automation

• Wireless alarm and security systems

• Industrial monitoring and control

• Long range irrigation system

http://www.szrfstar.com/

RF-42UH



1.4 Functional Block Diagram

Figure 1. Functional Block Diagram of RF-42UH

1.5 Part Number Conventions

The part numbers are of the form of RF-42UH where the fields are defined as follows:

Figure 2. Part Number Conventions of RF-42UH

RF 4

Company Name

RF-STAR

- 2

Communication Interface Mode

UART

TX Power

+20 dBm

U

Frequency Range

410 MHz ~ 525 MHz

H

Package Mode

Half-hole Package

32.0 MHz

MCU SX1278

SPI

Matching LPF

Matching

LDO

Switching

Low-pass Filter

Power Interface

Power Filter

Half-hole Interface

IPEX Connector Antenna

Switch


RF-42UH



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


RF-42UH



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-42UH ......................................................................................... 3

Figure 2. Part Number Conventions of RF-42UH ......................................................................................... 3

Figure 3. Pin Diagram of RF-42UH .................................................................................................................... 8

Figure 4. Photos of RF-42UH ............................................................................................................................. 12

Figure 5. Recommended PCB Footprint of RF-42UH (mm) ................................................................... 12

Figure 6. Schematic Diagram of RF-42UH ................................................................................................... 13


RF-42UH



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-42UH ........................................................................................................................ 7

Table 2. Pin Functions of RF-42UH .................................................................................................................... 8

Table 3. Recommended Operating Conditions of RF-42UH .................................................................. 10

Table 4. Handling Ratings of RF-42UH........................................................................................................... 10

Table 5. Current Consumption of RF-42UH .................................................................................................. 10

Table 6. Temperature Table of Soldering and Reflow ................................................................................ 31


RF-42UH



2 Module Configuration and Functions

2.1 Module Parameters

Table 1. Parameters of RF-42UH

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 SMT Packaging

Dimension 26.0 mm x 16.0 mm x (2.5 ± 0.1) mm

Antenna Half-hole interface / IPEX 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 @ 5 V

Tx Current 101 mA

Rx Current 15 mA

Sleep Current 3.4 μA


RF-42UH



2.2 Module Pin Diagram

Figure 3. Pin Diagram of RF-42UH

2.3 Pin Functions

Table 2. Pin Functions of RF-42UH

Pin Name Pin Type Description

1 GND - Ground

2 S0 I

Cooperate with S1 to determine the working mode.

(Cannot be NC, need be grounded if not used.)

3 S1 I

Cooperate with S0 to determine the working mode.

(Cannot be NC, need be grounded if not used.)

4 RXD I UART RX signal

5 TXD O UART TX signal

6 EN O

Pull the serial port high before sending data and pull low after sending.

Timed wake-up pin, pull high when wake-up.


RF-42UH



Pull high when module sending data, pull low after sending.

7 VCC - Power supply: 3.3 V ~ 5.2 V.

8 GND - Ground

9 RES_MCU I Reset pin, NC.

10 GND - Ground, NC.

11 3V3_MCU I/O VCC (Power supply pin when flash the firmware)

12 SWIM_MCU I/O SWIM pin of internal MCU

13 PB0 I/O NC

14 PB1 I/O NC

15 PB3 I/O NC

16 GND - Ground

17 GND - Ground

18 ANT I/O Antenna port

19 GND - Ground


RF-42UH



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-42UH

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-42UH

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-42UH

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


RF-42UH



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


RF-42UH



4 Application and Layout

4.1 Module Photos

Figure 4. Photos of RF-42UH

4.2 Recommended PCB Footprint

Figure 5. Recommended PCB Footprint of RF-42UH (mm)


RF-42UH



4.3 Schematic Diagram

Figure 6. Schematic Diagram of RF-42UH

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.


RF-42UH



5 Module Functions

5.1 Working Mode

RF-42UH 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


RF-42UH



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.


RF-42UH



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.


RF-42UH



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.


RF-42UH



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.


RF-42UH



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.


RF-42UH



6.5 EN Function

EN is used for wireless transceiver buffer indication and self-check indication. It indicates whether any data of the module

has not been transmitted through the wireless, whether the wireless data has been received but has not been completely

transmitted through the serial port, or the module is in the process of initial self-check.

1. Wake-up MCU

Figure 10. EN Timing Diagram of Wake-up Sleep MCU

2. Send indication

Figure 11. EN Timing Diagram during Sending Data

3. Receive indication


RF-42UH



Figure 12. EN Timing Diagram during Receiving Data

4. Configuration process

Figure 13. EN Timing Diagram during Setting Data

5. Cautions

⚫ EN outputting low level takes priority. When any low-level output condition is met, EN outputs low level. When all

low-level conditions are not met, EN outputs high level.

⚫ When the EN output in at low level, it means that the module is busy, and the working mode detection will not be

carried out at this time. When the module EN output is at high level, it means the mode switching will be completed

within 1 ms.

⚫ After switching to the new working mode, the module will enter the mode at least 2 ms after the rising edge of EN.

When the EN output is always at high level, the mode switching will take effect immediately.

⚫ When entering from sleep mode to other modes or during reset, the module will reset the parameters, during which

EN output is low.


RF-42UH



7 Command Format

7.1 AT Command

The supported instruction list is as follows (all operations of the module are conducted at the current baud rate in normal

mode, wake-up mode, and sleep mode):

No. Command Format Description

1 AT_READ

Send "AT_READ" in ASCII format, the module returns the saved parameters.

For example: "AT_READ=00,31,1A,3C,40".

Supports the operation in normal mode, wake-up mode, and sleep mode.

2 AT_VER

Send "AT_VER" in ASCII format, the module will return the version number.

For example: "AT_VER=A3,01,10,14".

Supports normal mode, wake-up mode, and sleep mode.

3 AT_RSSI

Send "AT_RSSI" in ASCII format, the module returns "AT_RSSI=value (hex)".

For example: "AT_RSSI = 2F".


4 “AT_SET=”

+ working parameters

Send “AT_SET=+ (5 bytes working parameters)” in ASCII format, and the

parameters are saved after power off.

For example: "AT_SET=00,31,1A,3C,40".


5 “AT_USET=”

+ working parameters

Send “AT_USET=+ (5 bytes working parameters)” in ASCII format, and the

parameters are not be saved after power off.

For example: "AT_USET = 00,31,1A, 3C, 40".


Note: Send AT_RSSI, return AT_RSSI=xx. Below the band of 525 MHz: Value = -157 + xx. Above the band of 779 MHz:

Value = -164 + xx.


RF-42UH



7.2 Parameters of Command Setting

7.2.1 Format

There are five groups in total, two bytes in each group, and 8 bits in each group.

For example: AT_SET=00,01,1A,3C,40

In normal mode, wake-up mode or sleep mode, you can directly input " AT_SET=00,01,1A,3C,40" in the serial port

assistant command box in ASCII, and press send button to get the module response. If the input is correct, the data just

entered will be returned.

7.2.2 Detailed Parameters

1. The first group of data represents the type of control command.

AT_SET represents the control command type, which is fixed to AT_SET and AT_USET.

AT_SET represents that the set parameters are saved after power off.

AT_USET represents that the set parameters are not saved after power failure.

2. The second group of data represents the module address.

By default [00 00], the module address range is 0 ~ 65535, and in Hex [00 00] ~ [FF FF]

3. The third group of data represents: serial parity bit, serial baud rate, and air rate of wireless signal.


RF-42UH



The specific understanding is as follows: [1A] is in hex, and its binary is [0001 1010].

bit7, bit6 means serial parity bit

bit7 bit6 Serial Parity BIt Description

0 0 8N1 (by default)

The serial port mode of communication module can be

different.

0 1 8O1

1 0 8E1

1 1 8N1 (Equivalent to 00)

bit5, bit4, bit3 means baud rate.

bit5 bit4 bit3 Baud Rate (bps) Description

0 0 0 1200

The baud rate of both sides of communication

module can be different. The baud rate of the serial

port is independent of the wireless transmission

parameters and does not affect the characteristics of

the wireless transceiver.

0 0 1 2400

0 1 0 4800

0 1 1 9600 (by default)

1 0 0 19200

1 0 1 38400

1 1 0 57600

1 1 1 115200

bit3, bit2, bit1 means air rate.

bit3 bit2 bit1 Air Rate (bps) Description

0 0 0 0.3k

The lower the air rate, the longer the distance. The

stronger the anti-interference performance and the

longer the transmission time.

The air rate of both sides must be the same.

0 0 1 1.2k

0 1 0 2.4k (by default)

0 1 1 4.8k

1 0 0 9.6k

1 0 1 19.2k

1 1 0 19.2k (Equivalent to 101)

1 1 1 19.2k (Equivalent to 101)

In summary, the parameters of [1A] (in hex) → [0001 1010] (in binary) are: [8N1, baud rate: 9600, air rate of 2.4k].

For example: The parameters needed are the module address of 1000 (in decimal), the serial parity bit of 8N1, the baud

rate of 19200, and air rate 19.2k. Expressed as:

⚫ Address is 1000 in decimal, and the hexadecimal representation is 0x03E8, express it as [03 E8].


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⚫ Serial parity bit is 8N1, and the binary representation is [00].

⚫ Baud rate is 19200, and the binary representation is [100]

⚫ Air rate is 19.2k, and the binary representation is [101]

All in all, it is [0010 0101], and converted to hexadecimal is [25]. The first four commands can be expressed as: [AT_SET

= 03,E8,25]

4. The fourth group of data represents the channel.

The channel range is 410 MHz ~ 525 MHz with 1 M interval. Channel 23 in decimal is [17] in hex, corresponding to

(410+ channels) MHz = 433 MHz. Channel 60 in decimal is [3C] in hex, corresponding to (410+ channels) MHz = 470

MHz.

The first five commands can be expressed as: [AT_SET = A0,03,E8,25,17]

5. The fifth group of data represents: transmission mode, IO driving method, wireless wake-up time, transmit

power.

The specific understanding is as follows: [40] is a hexadecimal representation, it needed to be converted to a binary

representation, that is, [0100 0000].

bit7 indicates the transmission mode

bit7 Transmission Mode Description

0 Transparent transmission When it is 1, the first three bytes of each user's data frame are used as

high, low address and channel. When transmitting, the module changes

its address and channel, and then restores the original settings after

completed.

1 Fixed point transmission

bit6 indicates the IO driven mode

bit6 IO Driven Mode (default as 1) Description

0 TXD, EN open circuit output,

RXD open circuit input This bit is used to enable the internal pull-up resistor of the module.

Open-drain mode has stronger level adaptability. In some cases, an

external pull-up resistor may be required. 1 TXD, EN push-pull output, RXD

pull-up input

bit5, bit4 and bit3 indicates the wireless wake-up time

bit3 bit2 bit1 Wake-up Time (ms) Description

0 0 0 250 (by default) The transceiver modules work in normal mode. The delay time is invalid

and can be any value. 0 0 1 500


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0 1 0 750 The transmitting module works in the wake-up mode and will

continuously transmit the call code for the corresponding time.

The receiving module works in low-power mode. This time refers to the

listening interval time (wireless wake-up) of the receiver and can only

receive data from the transmitting module working in wake-up mode.

0 1 1 1000

1 0 0 1250

1 0 1 1500

1 1 0 1750

1 1 1 2000

bit2 is reserved unused.

bit1 and bit0 indicate the transmit power.

bit1 bit0 Transmit Power

(Approximate Value) Description

0 0 20 dBm (by default) The external power supply must provide more than 250 mA current

output capability. And ensure that the power supply ripple is less than

100 mV. It is not recommended to use smaller power transmission,

because its power utilization efficiency is not high.

0 1 17 dBm

1 0 14 dBm

1 1 10 dBm

7.2.3 Examples

Examples: 1. Normal mode, 2. Push-pull output, 3. Wireless wake-up time of 500 ms, 4. Transmit power of 20 dBm. It

needs to be expressed as follows: (bit 2 is reserved unused and default as 0)

[1 001 0 00], converted to hexadecimal = [48]

The above can be expressed as: [AT_SET=03,E8,25,17,48]. What it means: All set parameters are saved after powered

off. The parameters are modified to: module address of 1000, serial parity bit of 8N1, baud rate of 19200, air rate of

19.2k, channel of 23 (frequency 433), normal mode, push-pull output, wake-up time of 500 ms and transmit power of 20

dBm.

Here are some common commands:

1. The second group of data: address

Address Number In Hex

Address 1 00 01

Address 2 00 02

Address 3 00 03

Address 30 00 1E

Address 31 00 1F


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Address 32 00 20

Address 60 00 3C

Address 61 00 3D

Address 62 00 3E

Address 101 00 65

Address 102 00 66

Address 103 00 67

2. The third group of data: serial parity bit, baud rate, air rate

Serial Parity Bite Baud Rate (bps) Air Rate (bps) In Binary In Hex

8N1 9600 0.3k 00 011 000 18

8N1 9600 2.4k 00 011 010 1A

8N1 9600 19.2k 00 011 101 1D

8N1 19200 0.3k 00 100 000 20

8N1 19200 2.4k 00 100 010 22

8N1 19200 19.2k 00 100 101 25

8N1 115200 0.3k 00 111 000 38

8N1 115200 2.4k 00 111 010 3A

8N1 115200 19.2k 00 111 101 3D

8O1 9600 0.3k 01 011 000 58

8O1 9600 2.4k 01 011 010 5A

8O1 9600 19.2k 01 011 101 5D

8O1 115200 0.3k 01 111 000 78

8O1 115200 2.4k 01 111 010 7A

8O1 115200 19.2k 01 111 101 7D

3. The fourth group of data: channel

Interval: 1M. 116 channels in total.

Channel Number Frequency (MHz) In Hex

1 410 01

10 420 0A

20 440 14


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23 433 17

40 450 28

60 470 3C

80 490 50

4. The fifth group of data: transmission mode, IO driving method, wireless wake-up time, transmit power (bit2

is not used and default as 0)

Transmission Mode IO Driven Mode Wake-up Time

(ms)

Transmit Power

(dBm) In Binary In Hex

Transparent transmission Open circuit output 250 20 0 0 000 0 00 00



Transparent transmission Push-pull output 250 20 0 1 000 0 00 40




Fixed point transmission Open circuit output 250 20 1 0 000 0 00 80

Fixed point transmission Open circuit output 1000 20 1 0 011 0 00 98

Fixed point transmission Open circuit output 1500 20 1 0 101 0 00 A8

Fixed point transmission Push-pull output 2000 20 1 1 111 0 00 F8

Fixed point transmission Push-pull output 250 20 1 1 000 0 00 C0

Fixed point transmission Push-pull output 1000 20 1 1 011 0 00 D8

Fixed point transmission Push-pull output 2000 20 1 1 111 0 00 F8


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8 Implementation

8.1 Hardware Design

1. It is recommended to offer the module with a DC stabilized power supply, a tiny power supply ripple coefficient and

the reliable ground. Please pay attention to the correct connection between the positive and negative poles of the

power supply. Otherwise, the reverse connection may cause permanent damage to the module;

2. Please ensure the supply voltage is between the recommended values. The module will be permanently damaged

if the voltage exceeds the maximum value. Please ensure the stable power supply and no frequently fluctuated

voltage.

3. When designing the power supply circuit for the module, it is recommended to reserve more than 30% of the margin,

which is beneficial to the long-term stable operation of the whole machine. The module should be far away from the

power electromagnetic, transformer, high-frequency wiring and other parts with large electromagnetic interference.

4. The bottom of module should avoid high-frequency digital routing, high-frequency analog routing and power routing.

If it has to route the wire on the bottom of module, for example, it is assumed that the module is soldered to the Top

Layer, the copper must be spread on the connection part of the top layer and the module, and be close to the digital

part of module and routed in the Bottom Layer (all copper is well grounded).

5. Assuming that the module is soldered or placed in the Top Layer, it is also wrong to randomly route the Bottom Layer

or other layers, which will affect the spurs and receiving sensitivity of the module to some degrees;

6. Assuming that there are devices with large electromagnetic interference around the module, which will greatly affect

the module performance. It is recommended to stay away from the module according to the strength of the

interference. If circumstances permit, appropriate isolation and shielding can be done.

7. Assuming that there are routings of large electromagnetic interference around the module (high-frequency digital,

high-frequency analog, power routings), which will also greatly affect the module performance. It is recommended

to stay away from the module according to the strength of the interference. If circumstances permit, appropriate

isolation and shielding can be done.

8. It is recommended to stay away from the devices whose TTL protocol is the same 433 MHz physical layer, for

example: USB 3.0.

9. The antenna installation structure has a great influence on the module performance. It is necessary to ensure the

antenna is exposed and preferably vertically upward. When the module is installed inside of the case, a high-quality

antenna extension wire can be used to extend the antenna to the outside of the case.

10. The antenna must not be installed inside the metal case, which will cause the transmission distance to be greatly

weakened.


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8.2 Trouble Shooting

8.2.1 Unsatisfactory Transmission Distance

1. When there is a linear communication obstacle, the communication distance will be correspondingly weakened.

Temperature, humidity, and co-channel interference will lead to an increase in communication packet loss rate. The

performances of ground absorption and reflection of radio waves will be poor, when the module is tested close to

the ground.

2. Seawater has a strong ability to absorb radio waves, so the test results by seaside are poor.

3. The signal attenuation will be very obvious, if there is a metal near the antenna or the module is placed inside of the

metal shell.

4. The incorrect power register set or the high data rate in an open air may shorten the communication distance. The

higher the data rate, the closer the distance.

5. The low voltage of the power supply is lower than the recommended value at ambient temperature, and the lower

the voltage, the smaller the power is.

6. The unmatchable antennas and module or the poor quality of antenna will affect the communication distance.

8.2.2 Vulnerable Module

1. Please ensure the supply voltage is between the recommended values. The module will be permanently damaged

if the voltage exceeds the maximum value. Please ensure the stable power supply and no frequently fluctuated

voltage.

2. Please ensure the anti-static installation and the electrostatic sensitivity of high-frequency devices.

3. Due to some humidity sensitive components, please ensure the suitable humidity during installation and application.

If there is no special demand, it is not recommended to use at too high or too low temperature.

8.2.3 High Bit Error Rate

1. There are co-channel signal interferences nearby. It is recommended to be away from the interference sources or

modify the frequency and channel to avoid interferences.

2. The clock waveform on SPI is not standard. Check whether there is interference on the SPI line. The SPI bus line

should not be too long.

3. The unsatisfactory power supply may also cause garbled. It is necessary to ensure the power supply reliability.

4. If the extension wire or feeder wire is of poor quality or too long, the bit error rate will be high.

8.3 Electrostatics Discharge Warnings

The module will be damaged for the discharge of static. RF-star suggest that all modules should follow the 3 precautions

below:


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1. According to the anti-static measures, bare hands are not allowed to touch modules.

2. Modules must be placed in anti- static areas.

3. Take the anti-static circuitry (when inputting HV or VHF) into consideration in product design.

Static may result in the degradation in performance of module, even causing the failure.

8.4 Soldering and Reflow Condition

1. Heating method: Conventional Convection or IR/convection.

2. Solder paste composition: Sn96.5 / Ag3.0 / Cu0.5

3. Allowable reflow soldering times: 2 times based on the following reflow soldering profile.

4. Temperature profile: Reflow soldering shall be done according to the following temperature profile.

5. Peak temperature: 245 ℃.

Table 6. Temperature Table of Soldering and Reflow

Profile Feature Sn-Pb Assembly Pb-Free Assembly

Solder Paste Sn63 / Pb37 Sn96.5 / Ag3.0 / Cu0.5

Min. Preheating Temperature (Tmin) 100 ℃ 150 ℃

Max. Preheating Temperature (Tmax) 150 ℃ 200 ℃

Preheating Time (Tmin to Tmax) (t1) 60 s ~ 120 s 60 s ~ 120 s

Average Ascend Rate (Tmax to Tp) Max. 3 ℃/s Max. 3 ℃/s

Liquid Temperature (TL) 183 ℃ 217 ℃

Time above Liquidus (tL) 60 s ~ 90 s 30 s ~ 90 s

Peak Temperature (Tp) 220 ℃ ~ 235 ℃ 230 ℃ ~ 250 ℃

Average Descend Rate (Tp to Tmax) Max. 6 ℃/s Max. 6 ℃/s

Time from 25 ℃ to Peak Temperature (t2) Max. 6 minutes Max. 8 minutes

Time of Soldering Zone (tP) 20±10 s 20±10 s


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Figure 14. Recommended Reflow for Lead Free Solder

8.5 Optional Packaging

Figure 15. Optional Packaging Mode

Note: Default tray packaging.


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9 Revision History

Date Version No. Description Author

2018.12.28 V0.9 The initial version is released. Aroo Wang

2019.01.27 V1.0 Update module picture. Aroo Wang

2019.03.06 V1.1 Add part number conventions. Aroo Wang

2019.06.05 V1.2 Add the Chapter of Application, Implementation, and

Layout Aroo Wang

2019.06.19 V1.3 Update the description. Aroo Wang

2020.01.19 V1.3 Add LoRa module list. Sunny Li

Note:

1. The document will be optimized and updated from time to time. Before using this document, please make sure it is

the latest version.

2. To obtain the latest document, please download it from the official website: www.szrfstar.com.


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10 Contact Us

SHENZHEN RF-STAR TECHNOLOGY CO., LTD.

Shenzhen HQ:

Add.: Room 601, Block C, Skyworth Building, High-tech Park, Nanshan District, Shenzhen, Guangdong, China

Tel.: 86-755-3695 3756

Chengdu Branch:

Add.: No. B3-03, Building No.1, Incubation Park, High-Tech District, Chengdu, Sichuan, China, 610000

Tel.: 86-28-6577 5970

Email: [email protected], [email protected]

Web.: www.szrfstar.com

http://www.szrfstar.com/mailto:[email protected]://www.szrfstar.com/

RF-star LoRa Module List1 Device Overview1.1 Description1.2 Key Features1.3 Applications1.4 Functional Block Diagram1.5 Part Number Conventions

Table of ContentsTable of FiguresTable of Tables2 Module Configuration and Functions2.1 Module Parameters2.2 Module Pin Diagram2.3 Pin Functions

3 Specifications3.1 Recommended Operating Conditions3.2 Handling Ratings3.3 Current Consumption

4 Application and Layout4.1 Module Photos4.2 Recommended PCB Footprint4.3 Schematic Diagram4.4 Reference Design of the Connection between MCU and Module

5 Module Functions5.1 Working Mode5.2 Mode Switching (0 for Low Level, 1 for High Level)5.3 Normal Mode5.4 Wake-up Mode5.5 Low-power Mode5.6 Sleep Mode5.7 Data Security

6 Module Functions6.1 Transparent Transmission6.2 Fixed Point Transmission6.3 Broadcast and Listening6.4 Module Reset6.5 EN Function

7 Command Format7.1 AT Command7.2 Parameters of Command Setting7.2.1 Format7.2.2 Detailed Parameters7.2.3 Examples

8 Implementation8.1 Hardware Design8.2 Trouble Shooting8.2.1 Unsatisfactory Transmission Distance8.2.2 Vulnerable Module8.2.3 High Bit Error Rate

8.3 Electrostatics Discharge Warnings8.4 Soldering and Reflow Condition8.5 Optional Packaging

9 Revision History10 Contact Us

Documents

RF-42UH SX1278 433 MHz LoRa Module · 2020. 8. 28. · RF-42UH SX1278 433 MHz LoRa Module Version 1.3 Shenzhen RF-star Technology Co., Ltd. Jan. 19th, 2020