RadioMaster ER5C V2 – Five-Channel PWM ExpressLRS Receiver for RC Cars and Boats

RadioMaster ER5C V2 is a compact 2.4 GHz ExpressLRS receiver designed for RC cars, boats and other surface and marine models. Five PWM outputs, built-in voltage telemetry and a temperature-compensated crystal oscillator (TCXO) combine versatile control options with a design that supports stable radio communication.

This receiver suits model builders who want to use an ExpressLRS control link with conventional PWM-controlled servos and electronic speed controllers. Configuration and firmware updates over Wi-Fi make it easier to adapt the receiver to a particular model’s requirements.

Five PWM Channels for Model Control

RadioMaster ER5C V2 provides five PWM outputs for controlling up to five servos or connecting compatible electronic speed controllers and other devices that use PWM signals. Direct PWM outputs allow compatible equipment to connect to the receiver without a separate signal converter.

In an RC car, these channels can control a steering servo, electronic speed controller and additional functions. In a model boat, they can handle rudder, motor or other mechanism controls. Specific applications depend on connected devices and radio controller settings.

ExpressLRS settings allow control channels to be mapped to different receiver outputs. This provides flexibility when a model’s wiring or preferred control layout differs from standard channel assignments.

ExpressLRS 2.4 GHz Control Link

The receiver uses the open-source ExpressLRS radio system in the 2.4 GHz band. It is compatible with suitable external ELRS transmitter modules and radio controllers featuring a built-in 2.4 GHz ExpressLRS module.

To establish a connection, transmitter and receiver firmware major versions must be compatible. When upgrading an existing radio system, check both the frequency band and firmware versions. ExpressLRS also supports a shared binding phrase to simplify pairing.

TCXO Supports Frequency Stability

RadioMaster ER5C V2 features a temperature-compensated crystal oscillator, or TCXO. It helps reduce frequency drift caused by temperature changes and maintains an accurate operating frequency.

Electronics can change temperature during use due to ambient conditions and heat generated by other components in the model. TCXO compensates for the effects of these temperature changes on the oscillator, helping maintain a stable control link. Actual link quality also depends on antenna placement, transmitter performance and operating conditions.

Voltage Telemetry for Battery and Power System Monitoring

Built-in voltage telemetry sends receiver supply voltage or external battery voltage readings to the radio controller. The receiver automatically detects which voltage input to use for telemetry. The telemetry voltage measurement range is 4.0–35 V, with 10 mW telemetry transmission power.

A dedicated telemetry connection is used to monitor external battery voltage. This allows users to track model battery voltage even when the receiver itself is powered by an electronic speed controller’s BEC output. A BEC is a voltage regulator that supplies the receiver and connected control equipment with a suitable voltage.

Receiver operating voltage is 4.5–8.4 V DC. The measurement range of up to 35 V applies to the telemetry voltage sensing input, not the receiver’s standard power input. When choosing a power supply, also consider the permitted voltage range of connected servos and other devices.

Configuration and Firmware Updates over Wi-Fi

RadioMaster ER5C V2 supports firmware updates over Wi-Fi and configuration through the WebUI interface. After connecting to the receiver’s Wi-Fi network, users can open its configuration interface in a phone or computer browser.

The web interface allows channel-to-output mapping and failsafe settings to be adjusted. This lets users tailor receiver behaviour to a model’s control requirements. For example, an electronic speed controller should be configured to use an appropriate stop or neutral setting if the control link is lost.

When configuring a PWM output, the selected signal frequency must be compatible with the connected servo or other device. Available configuration options depend on receiver firmware version.

Compact and Lightweight Design

The receiver measures 30 × 18.5 × 13 mm and weighs 5.7 g. Its small dimensions make installation easier in models with limited space for electronics.

Package contents include a RadioMaster ER5C V2 receiver, a voltage telemetry cable and a user guide card. Five PWM channels, voltage telemetry and browser-based configuration make it a practical receiver for building a new RC model or converting an existing model to ExpressLRS.