Product overview
The Happymodel CrossF4 ELRS 1-2S is a flight controller for Tinywhoop builds, combining flight processing, four motor-control channels and a UART ExpressLRS receiver in an integrated electronics assembly. Its STM32F411CEU6 processor runs at 100MHz with 512K flash, paired with a BMI270 sensor connected over SPI. Built-in Betaflight OSD, voltage detection, current sensing and a 5V 1A BEC provide additional integration functions. A 31mm enameled copper-wire antenna serves the receiver, while 16Mb onboard flash provides Blackbox storage.
The controller accepts 1-2S LiPo or LiHV input across DC 2.8V~8.7V. Its onboard BLHeli_S 4-in-1 ESC is rated at 5A per channel, with 6A peak limited to five seconds, and supports DSHOT150, DSHOT300 and DSHOT600. Factory receiver firmware is ExpressLRS V3.0.1, with CRSF communication and selectable packet rates from 25Hz to 500Hz. Binding requires an ExpressLRS transmitter module running V3.X. Receiver updates use ExpressLRS Configurator, and onboard Blackbox requires the specified CLI configuration.
Specifications
| Specification | Value & conditions |
|---|---|
| Product type and intended application | Happymodel CrossF4 ELRS 1-2S flight controller for Tinywhoop, with BMI270 IMU and serial UART ExpressLRS receiver. |
| Flight controller firmware target | CRAZYBEEF4DX4.3.2 |
| Flight controller processor | STM32F411CEU6; 100MHz; 512K FLASH. |
| Inertial sensor | BMI270 with SPI connection. |
| Flight controller supply voltage | DC 2.8V~8.7V.1-2S LiPo or LiHV battery input. |
| Integrated motor control | Built-in BLHeli_S 4-in-1 ESC; 5A each; Dshot300 ready. |
| On-screen display | Built-in Betaflight OSD with SPI control. |
| Integrated receiver | Built-in UART ExpressLRS 2.4GHz receiver. |
| Battery eliminator circuit | Built-in 5V 1A BEC. |
| Electrical monitoring | Built-in voltage detection and current sensor. |
| Blackbox storage | 16Mb onboard flash for Blackbox. |
| ESC processor | EFM8BB21. |
| ESC supply voltage | 2.8v~8.7v.1-2S LiPo/LiPo HV supply. |
| ESC current ratings | 5A continuous; 6A peak.Peak current duration: 5 seconds. |
| ESC programming | Programmable through BLHeliSuite. |
| ESC firmware | S_H_50_REV16_8.HEXFactory configuration. |
| ESC protocols | DSHOT150/DSHOT300/DSHOT600. |
| Receiver packet rate options | 25Hz/50Hz/150Hz/250Hz/500Hz. |
| Receiver RF frequency | 2.4GHz. |
| Receiver antenna | Enameled copper wire, 31mm long. |
| Receiver transmit power | Less than 12dBm.Telemetry output. |
| Receiver protocol | CRSF. |
| Receiver firmware | ExpressLRS V3.0.1.Factory configuration. |
| Receiver hardware | Same receiver hardware as Happymodel EP1. |
| Receiver firmware update method | Firmware can be updated through ExpressLRS Configurator. |
| Receiver firmware target | HappyModel EP1/2 2400 RX. |
| Transmitter firmware requirement | ExpressLRS TX module must first be upgraded to V3.X; binding follows the Happymodel EP1/EP2 procedure.Binding with the onboard UART ExpressLRS receiver. |
| Blackbox configuration | Set blackbox_device = SPIFLASH; set flash_spi_bus = 2; resource FLASH_CS 1 a14; save.Enabling onboard Blackbox through the CLI. |
| Factory configuration file | CrossF4 ELRS diff for betaflight 4.3.2.Betaflight 4.3.2. |
