Spektrum SR300 - User Manual

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Failsafe

Failsafe positions are also set during binding. In the unlikely event that the radio link is lost during use,

the receiver will drive the servos to their preprogrammed failsafe positions (normally full brakes and

straight steering). If the receiver is turned on prior to turning on the transmitter, the receiver will enter

failsafe mode, driving the servos to their preset failsafe positions. When the transmitter is turned on,

normal control is resumed.

Tips on Using Spektrum 2.4GHz

Your DSM equipped 2.4GHz system is intuitive to operate, functioning nearly identically to FM

systems. Following are a few common questions from customers.

1. Q: Which do I turn on ﬁrst, the transmitter or the receiver?

A: It doesn’t matter, if the receiver is turned on ﬁrst, all channels will be driven to the failsafe

position set during binding. When the transmitter is then turned on, the transmitter scans the

2.4GHz band and acquires an open channel. Then the receiver that was previously bound

to the transmitter scans the band and ﬁnds the GUID (Globally Unique Identiﬁer code) stored

during binding. The system then connects and operates normally. If the transmitter is turned on

ﬁrst, the transmitter scans the 2.4GHz band and acquires an open channel. When the receiver

is turned on, the receiver scans the 2.4GHz band looking for the previously stored GUID. When

it locates the speciﬁc GUID code and conﬁrms uncorrupted repeatable packet information, the

system connects and normal operation takes place. Typically this takes 2 to 6 seconds.

2. Q: Sometimes the system takes longer to connect and sometimes it doesn’t connect

at all. Why?

A: In order for the system to connect (after the receiver is bound) the receiver must receive a large

number of consecutive uninterrupted perfect packets from the transmitter. This process is

purposely critical of the environment ensuring that it’s safe to use when the system does connect.

If the transmitter is too close to the receiver (less than 4 ft) or if the transmitter is located near

metal objects (metal Tx case, the bed of a truck, the top of a metal work bench, etc.), connection

will take longer and in some cases connection will not occur as the system is receiving reﬂected

2.4GHz energy from itself and is interpreting this as unfriendly noise. Moving the system away

from metal objects or moving the transmitter away from the receiver and powering the system

again will cause a connection to occur. This only happens during the initial connection. Once

connected the system is locked in and should a loss of signal occur (failsafe) the system

connects immediately (4ms) when signal is regained.

3. Q: I’ve heard that the DSM system is less tolerant of low voltage. Is this correct?

A: The SR300 has an operational voltage range of 3.5 to 9.6 volts. With most systems this is not

a problem as in fact most servos cease to operate at around 3.8 volts. When using multiple

high-current draw servos with an inadequate battery/power source, heavy momentary loads can

cause the voltage to dip below this 3.5-volt threshold thus causing the entire system (servos and

receiver) to brown out. When the voltage drops below the low voltage threshold (3.5 volts), the

receiver must reboot.

4. Q: Sometimes my receiver loses its bind and won’t connect, requiring rebinding.

What happens if the bind is lost during use?

A: The receiver will never lose its bind unless it’s instructed to. It’s important to understand that

during the binding process the receiver not only learns the GUID (code) of the transmitter but

the transmitter learns and stores the type of receiver that it’s bound to.

If the system fails to connect, more than likely the transmitter is near conductive material

(transmitter case, truck bed, etc.) and the reﬂected 2.4GHz energy is preventing the system

from connecting. (See #2 above)

SR300 Instruction Manual

Spektrum’s SR300 3-channel DSM

Sport Surface receiver is compatible with all Spektrum surface

transmitters and operates in DSM mode.

Speciﬁcations

Type: DSM

Channels: 3

Band: 2.4GHz

Dimensions (LxWxH): 1.60 x 1.06 x .58 in (41 x 27 x 15mm)

Weight: .3 oz (9 g)

Voltage Range: 3.5–9.6V

Binding Receiver to Transmitter

In order to operate, the receiver must be bound to the transmitter. Binding is the process of teaching

the receiver the speciﬁc transmitter’s code called GUID (Globally Unique Identiﬁer). When a receiver is

bound to a transmitter/model memory, the receiver will only respond to that speciﬁc transmitter/model

memory.

Binding

Note: The SR300 receiver utilizes the DSM protocol.

1. With the receiver off, insert the bind plug into the BIND port in the receiver.

2. Power the receiver through any port. If an ESC is being used, power on the ESC with the ESC lead

plugged in the throttle channel port. The green LED will ﬂash continuously indicating that the receiver

is in bind mode.

3. With the steering wheel, throttle trigger and Aux channel (if applicable) in the desired preset failsafe

positions, initiate the bind process with your Spektrum transmitter which will also store the failsafe

positions. Please see the next section for more information about Failsafe.

4. The LED on the receiver should now be solid, indicating a successful bind has taken place.

5. Once the bind process is complete and before power is cycled on the receiver, remove the bind plug

and store it in a convenient place. Failure to remove the bind plug will result in the receiver going

back into bind mode.

Note:

The only time it is necessary to do a rebind is if different failsafe positions are desired e.g., servo travel

has been reversed after the initial bind, or if the receiver is to be bound to a different model memory.

Powering the

receiver with a

separate

receiver pack

Powering the

receiver with an ESC

Bind Plug

Declaration of Conformity

(in accordance with ISO/IEC 17050-1)

No. HH2008111002

Product(s): SR300 Receiver

Item Number(s): SPMSR300

Equipment class: 1

The object of declaration described above is in conformity with the requirements of the

speciﬁcations listed below, following the provisions of the European R&TTE directive 1999/5/EC:

EN 301 489-1, 301 489-17 General EMC requirements for Radio equipment

Signed for and on behalf of:

Horizon Hobby, Inc.

Champaign, IL USA

Nov. 10, 2008

Steven A. Hall

Vice President

International Operations and Risk Management

Horizon Hobby, Inc.

Revised11/08 14301.1

LED

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Summary

Binding Receiver to Transmitter

Binding

Process to teach the receiver the specific transmitter's code (GUID) for secure operation.

Tips on Using Spektrum 2.4 GHz

Transmitter and Receiver Power Sequence

Explains the correct power-on sequence for transmitter and receiver.

Connection Issues and Interference

Discusses connection problems due to proximity to metal or reflected 2.4GHz energy.

Low Voltage Tolerance and Brown-outs

Addresses voltage range and potential brown-out issues with high-current servos.

Bind Loss and Connection Failures

Clarifies bind loss causes and discusses connection failures and rebinding.

Summary

Binding Receiver to Transmitter

Binding

Process to teach the receiver the specific transmitter's code (GUID) for secure operation.

Tips on Using Spektrum 2.4 GHz

Transmitter and Receiver Power Sequence

Explains the correct power-on sequence for transmitter and receiver.

Connection Issues and Interference

Discusses connection problems due to proximity to metal or reflected 2.4GHz energy.

Low Voltage Tolerance and Brown-outs

Addresses voltage range and potential brown-out issues with high-current servos.

Bind Loss and Connection Failures

Clarifies bind loss causes and discusses connection failures and rebinding.

The device described in the manual is the Spektrum SR300 3-channel DSM® Sport Surface receiver.

Function Description

The SR300 is a radio receiver designed for use with surface remote control vehicles. Its primary function is to receive control signals from a compatible Spektrum surface transmitter and translate them into commands for the vehicle's servos. It operates using the DSM (Digital Spectrum Modulation) protocol, which is a proprietary 2.4GHz spread spectrum technology developed by Spektrum. This protocol ensures a robust and reliable radio link by constantly scanning the 2.4GHz band and acquiring an open channel for communication, minimizing interference.

A key feature of the SR300 is its binding process. Binding is the procedure by which the receiver learns the specific Globally Unique Identifier (GUID) code of a particular transmitter (or model memory within a transmitter). Once bound, the receiver will only respond to signals from that specific transmitter/model memory, preventing accidental control by other transmitters. This process also establishes failsafe positions for the servos. In the event of a lost radio link during operation, or if the receiver is powered on before the transmitter, the servos will automatically move to these pre-programmed failsafe positions (typically full brakes and straight steering). This ensures a controlled response in critical situations, enhancing safety. When the transmitter is subsequently turned on, normal control is resumed.

The system is designed to be intuitive, functioning similarly to traditional FM (Frequency Modulation) systems, but with the added benefits of 2.4GHz technology, such as reduced interference and a more secure link. The connection process involves the receiver receiving a series of consecutive, uninterrupted, and perfect packets from the transmitter to ensure a safe operating environment.

Important Technical Specifications

Type: DSM
Channels: 3 (indicating it can control up to three distinct functions, typically steering, throttle, and an auxiliary function)
Band: 2.4GHz (operating in the 2.400-2.4835 GHz ISM band, which is globally recognized for industrial, scientific, and medical applications, and is license-free)
Dimensions (LxWxH): 1.60 x 1.06 x .58 inches (41 x 27 x 15 mm)
Weight: .3 oz (9 g)
Voltage Range: 3.5-9.6V (This wide range allows for compatibility with various power sources commonly used in RC vehicles, from 4-cell NiMH packs to 2S LiPo batteries, provided the voltage remains within this operational window.)
Compatibility: Compatible with all Spektrum surface transmitters.

Usage Features

Binding Procedure:
- Insert the bind plug into the BIND port of the receiver while the receiver is off.
- Power the receiver through any available port (e.g., via an ESC plugged into the throttle channel).
- The green LED on the receiver will flash continuously, indicating it is in bind mode.
- With the transmitter's steering wheel, throttle trigger, and auxiliary channel (if applicable) set to the desired failsafe positions, initiate the bind process on the Spektrum transmitter. This action also stores the failsafe positions.
- The receiver's LED will turn solid green, confirming a successful bind.
- Crucially, the bind plug must be removed before cycling power to the receiver; otherwise, it will re-enter bind mode.
- Rebinding is only necessary if different failsafe positions are desired (e.g., after reversing servo travel) or if the receiver needs to be bound to a different model memory on the transmitter.
Power-On Sequence: The system is flexible regarding the power-on sequence.
- If the receiver is turned on first, all channels will go to their pre-set failsafe positions. Once the transmitter is turned on, it will scan the 2.4GHz band, acquire an open channel, and then the receiver will locate the transmitter's GUID code, connect, and resume normal operation.
- If the transmitter is turned on first, it scans for an open channel. When the receiver is then turned on, it scans for the stored GUID, connects, and normal operation begins. This connection process typically takes 2 to 6 seconds.
Connection Reliability: The system is designed for robust connection. It requires a significant number of consecutive, uninterrupted, and perfect packets from the transmitter to establish a connection, ensuring a safe operating environment. However, certain environmental factors can affect connection time:
- Proximity to Receiver: If the transmitter is too close to the receiver (less than 4 ft), connection may take longer or fail.
- Metal Objects: Placing the transmitter near metal objects (e.g., a metal Tx case, truck bed, metal workbench) can cause reflected 2.4GHz energy, which the system interprets as noise, hindering connection. Moving the system away from metal objects or increasing the distance between the transmitter and receiver typically resolves this issue. This only affects the initial connection; once connected, the system is locked in.
Low Voltage Tolerance: The SR300 has an operational voltage range of 3.5 to 9.6 volts. While most servos cease to operate around 3.8 volts, heavy momentary loads from multiple high-current draw servos with an inadequate battery/power source can cause the voltage to dip below the 3.5-volt threshold. If the voltage drops below this threshold, the receiver must reboot, leading to a temporary loss of control.

Maintenance Features

Bind Plug Management: The bind plug is a critical tool for initial setup and re-binding. It must be stored in a convenient place and removed from the receiver after a successful bind to prevent the receiver from re-entering bind mode upon power cycling.
Environmental Awareness: Users are advised to be aware of the operating environment, particularly regarding metal objects and the proximity of the transmitter to the receiver during the initial connection phase. This helps ensure a quick and reliable connection.
Power System Monitoring: Given the receiver's low voltage tolerance, it is important to ensure that the vehicle's battery and power system are adequate for the demands of the servos being used, especially with high-current draw servos. Monitoring battery voltage and ensuring a healthy power supply helps prevent brownouts and ensures consistent operation.
No Loss of Bind: The receiver is designed not to lose its bind unless explicitly instructed to re-bind. This means that once bound, the receiver will reliably connect to its paired transmitter, provided environmental conditions are favorable. If connection issues arise, it's more likely due to environmental interference (e.g., reflected 2.4GHz energy from conductive materials) rather than a lost bind.