SNM401 Ad Hoc Network Module

1. Product Description

SNM401 Centerless Ad Hoc Network Module realizes centerless long-distance communication between modules, and adopts the world’s latest LDPC encoding and decoding technology, compared to the RS level used by traditional radio stations The concatenated convolutional code can have a coding gain of 5dB, and at the same time, through the “self-relay wireless communication” technology, it innovatively realizes automatic relay between modules, thereby greatly improving the coverage effect and transmission distance. SNM401 adopts ad-hoc network wireless communication technology, any node can receive and process the same signal forwarded by multiple nodes at the same time, combine these signals forwarded from different nodes, demodulate the original information to the greatest extent possible, and have a larger transmission distance and higher transmission reliability. The wireless communication technology of the ad hoc network does not require routing, and multiple nodes automatically determine whether to start the forwarding according to the received signal quality and field strength, and the relay is upgraded from a multi-hop single-point relay to a multi-hop multi-point relay. The state relay is upgraded to a mesh relay. When any node in the relay network is disconnected from the network, other relay lines in the relay network work normally so that the relay effect is not affected.

2. Product features

◆Operating frequency: 400-500MHz

◆Single-hop transmission distance: 3～5Km

◆Dynamic topology convergence: 1ms

◆Transmit power: 1W

◆Receive sensitivity: -127dBm

◆Working voltage: 3.5-4.5V

◆Signal to noise ratio Threshold: 1dB

◆Channel spacing: 12.5KHz

◆Frequency stability: 1ppm

◆Intermodulation: 65dB

◆Encryption: 256AES

◆Spurious response immunity: 75dB

◆Adjacent channel selectivity: 65dB@12.5KHzz

◆Operating temperature: -40～ +85℃

◆Module size: 33.5X42X3.4mm

3. Application

◆Internet of Things ◆Individual Soldier System ◆Emergency Broadcasting

◆UAV ◆Real-time Remote Control ◆Digital Intercom

◆Emergency Communication ◆Robot ◆Wireless Data Transmission

4. Working Parameters

Table 1: Operating Parameters Table

Parameter	Conditions	Minimum	Typical	Maximum	Unit
Operating Frequency Band		400		500	MHz
Operating Temperature		-40	25	+85	℃
Operating Voltage		3.5	4	4.5	V
Transmitting Power			30		dBm
Receiving Sensitivity		-130	-127	-125	dBm
Maximum RF Input Power				+33	dBm
serial port baud rate			115200		bps
sleep current	@ EN=0		40		uA
receive current			160		mA
transmit instantaneous current	@VCC==4V, 1W			1800	mA
transmit average current	@VCC==4V, 1W		600		mA
audio input voltage				1.5	VPP
audio output Impedance			150		Ohm

Note: If the working conditions of the module exceed the above limit values, it may cause permanent damage to the module.

5. Module pins and definitions

Figure 1 SNM401 Pin Diagram

Abbreviation	Description
AI	Analog input
AO	Analog output
AIO	Analog bi-direction
DI	Digital input
DO	Digital output
DIO	Digital bi-direction
P	Power
G	Ground

Table 3 SNM401 pin definition

Pin NO	Pin name	Type	Description
1	GND	G	GND
2	ANT	AIO	antenna port
3	GND	G	GND
4	GND	G	GND
5	VBAT	P	External 3.5V-4.5V battery or power supply, 4V is recommended
6	VBAT	P
7	GND	G	GND
8	GND	G	GND
9	TX_STATE	DO	module transmit indication Signal, the high level is transmitting
10	RX_STATE	DO	module receiving indication signal, the high level is receiving
11	NC		No connect
12	NC		No connect
13	GND	G	GND
14	TXD	DO	serial port data transmitting pin
15	RXD	DI	serial port data receiving pin
16	SET	DI	module Serial port configuration signal, configure parameters when high level, send and receive data when low level
17	EN	DI	module open enable signal, high level open, low level close
18	GND	G	GND
19	PRO1	DIO	programmable definition pin
20	PRO2	DIO	programmable Definition pin

: The module is regulated by 3.3V LDO inside, and all digital IOs are 3.3V level.

 

6. Package size

Figure 2 SNM401 size chart

Figure 3 SNM401 package Figure

7. LAYOUT precautions

1.TheSNM401 module works at 400-500MHzand the influence of various factors on wireless transceivers should be avoided.

2. It is laid under the module GND, and the traces are extended to the periphery as far as possible.
3. It is recommended to use insulating material to isolate the module mounting position on the substrate, for example, place a whole piece of in this position

silkscreen

4. Try to take a short and thick power line to the module, the recommended copper line width is80mil, and the decoupling capacitor should be placed as close to the power pin as possible.

8. Software configuration

8.1 Parameter configuration

Users can obtain and configure parameters through the serial port, the serial port baud rate is 115200, the data bit is 8bit, the stop bit is 1bit, and there is no parity bit.

Table 4 Serial port packet format

Serial port table packet
identification word	length	Command	instruction reply/reply content
1Byte	1Byte	1Byte	NByte

8.1.1 Identification word

The identification word is fixed as 0x68.

8.1.2 Length

Length = command + command content/reply content.

8.1.3 Command

List 5 Serial Command-List

Function	Command	Content	Reply Content
Acquire RF Parameters	0x00	No	Frequency(4Byte) +Power(1Byte) +Configuration Status(1Byte) +Noise(2Byte) +Baseband Version Number(1Byte)
Set RF Parameter	0x01	Frequency(4Byte) +Power(1Byte)	No
data relay level	0x0C	No	data relay level(1Byte)
Set data relay level	0x0D	Data relay level(1Byte)	No
key to acquire	0x0E	No	key(32Byte)
set key	0x0F	key(32Byte)	no
get module version	0x12	no	module name + version number
module ready	0x55	no	no
save configuration	0x66	no	no
data receive	0xA2	no	transparent data (NByte)
data send	0xB2	transparent data (NByte)	no

8.1.4 Instruction content/reply content

8.1.4.1 Obtaining RF parameters

Frequency: The unit is Hz, the setting range is ~5000000000, and the precision is 500HHz.

Power:1-high power 1W,0-low power 0.5W, the default is high power 1W.

Configuration status: Indicates the radio configuration status,0-uninitialized,1-configuring,2-configured successfully.

Noise Floor: Indicates the current frequency noise intensity, which 2 is meaningful

Baseband version number: The upper 4 bits represent the major version number, and the lower 4 bits represent the minor version number.

Configuration Packet:0x68 0x01 0x00

Return Packet:0x68 0x0A 0x00 Frequency Power Configuration Status Noise Floor Baseband Version No.

8.1.4.2 Setting RF Parameters

After configuring RF parameters, you must wait for the successful configuration (about 2 seconds) before the module can enter the setting work correctly state.

Configuration package:0x68 0x06 0x01 Frequency power

return package:0x68 0x01 0x01

8.1.4.3 Obtaining data relay level

SH ad hoc network technology is a simulcast mesh relay method, which does not require routing, which can greatly improve the coverage.number of relay hops N refers to the number of hops that can be relayed during data transmission, and the maximum number of relay hops is 16. With each additional hop, the transmission distance doubles, but the transmission time increases accordingly, as shown in the table below.

Table 6 Comparison of Relay Levels

Relay Hops	Transmission Bytes	Transmission Time
N	<36	N*50ms
N	37-72	N*100ms
N	73-108	N*150ms
N	109-144	*200ms
N	145-180	N*250ms
N	181-216	N*300ms
N	217-252	N*350ms
N	253-288	N*400ms

Configuration package: 0x68 0x01 0x0C

Return package: 0x68 0x02 0x0C Data relay level

8.1.4.4 Set data relay level

Configuration package:0x68 0x02 0x0D Data relay level

return packet:0x68 0x01 0x0D

8.1.4.5 Obtain the key

key for communication encryption, the module will automatically discard the voice information and data information whose key is inconsistent with its own key, and the key is all 0.

Configuration Packet:0x68 0x01 0x0E

Return Packet:0x68 0x21 0x0E Key

8.1.4.6 Set Key

Configuration Packet:0x68 0x21 0x0F Key

Return Packet:0x68 0x01 0x0F

8.1.4.7 Get Module Version

Configuration Packet:0x68 0x01 0x12

Return Packet:0x68 0x15 0x12 0x53 0x69 0x6d 0x75 0x6c 0x48 0x6f 0x63 0x32 0x31 0x38 0x5f 0x31 0x31 0x30 0x2e 0x30 0x00 is“Simulhoc2618_V1.0.0”

8.1.4.8 module

Return package:0x68 0x01 0x55

8.1.4.9 Save configuration

command to save all settings to Flash, and the saved configuration will be used directly after power-on.

Configuration package:0x68 0x01 0x66

Return package:0x68 0x01 0x66

8.1.4.10 Data reception

When the SET pin is low, the module will transparently transmit the received data package to the user. The length varies according to the actual transparent transmission data length.

Return package:0x68 Length 0xA2 Transparent

8.1.4.11 Data transmission

Only when the SET pin is at a low level can data be transmitted, and the data sent in a single transmission does not exceed 36 bytes. The length varies according to the actual transparent transmission data length. If a return packet is received, it indicates that the data transmission failed this time.

Configuration package: 0x68 Length 0xB2 Transparent data

return package: 0x68 0x01 0xB