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The Happymodel 2.4GHz ELRS nano series receiver is an open source program based on ExpressLRS, we have 3 types rx module released.

The PP RX is designed by @Jye Smith from ExpressLRS development team. Its main hardware architecture is STM32L432KBU6 MCU and SX1280 RF chip. It has a built-in ceramic antenna, which is super light and small in size.

On the basis of PP RX, we have developed the Nano 2.4GHz rx of ESP8285 version named EP1 and EP2.  The RF module of EP1/EP2 is the same like PP RX and use ESP8285 MCU . So you can upgrade firmware by WIFI , that’s too simple .

Due to the low-latency and high-refresh-rate RF module, they are very comfortable for FPV race and Long Range FPV. And very suitable for Tiny whoop because of the ultra light and Nano size.

SPECIFICATIONS:

• Type: ISM
  
• ESP8285 MCU
  
• SX1280IMLTRT RF Module
  
• Omnidirectional antenna
  
• Frequency Range: 2400 MHz to 2500 MHz
  
• Maximum receive refresh rate: 500Hz
  
• Minimum receiver refresh rate: 25Hz
  
• Working voltage: 5v
  
• Weight: 0.42gram(without antenna)
  
• Dimension: 10mm*10mm*3mm
  
• Peak gain: 2.23dB
  
• Package include 1pcs 40mm and 1pcs 90mm Omnidirectional antenna

PACKAGE INCLUDES:

• 1 x Happymodel 2.4g ExpressLRS EP1 RX Receiver module
• 1x Short Antenna
• 1x Long Antenna

Notes:
Since the Official Perfect version of ELRS firmware has not been released yet, currently our PP_RX, EP1/EP2 RX and ES24TX pre-loaded firmware are all beta versions, you can upgrade the official firmware when Official perfect target available.

More details
https://github.com/ExpressLRS/ExpressLRS

Bind procedure:

1. Supply power to the PP/EP1/EP2 rx, wait until the LED on the RX is off, immediately turn off the power, and then repeat again the above steps. When the RX is powered on for the third time, the LED light will start to double-flash, which means that the RX enters the binding mode
2. Insert the ES24TX module or other DIY 2.4G ELRS TX to Radio transmitter, and choose External RF mode to CRSF protocol, then you can find ELRS menu from the Radio systems(Need to copy the ELRS.LUA file to the SD-Card tools first), Enter into ELRS and press [Bind], the LED on the RX module will getting to be solid if bind successfully.
3. Receiver LED status meanings:
   PP RX: LED solid means bind successful or Connection established; LED double-flash means in bind mode; LED flash slowly means no signal connection from the TX module
   EP1/EP2 RX: LED solid means bind successful or Connection established; LED double-flash means in bind mode; LED flash slowly means no signal connection from the TX module; LED flash fast means in WIFI hotspot mode, you can connect the WIFI of the RX and upgrade firmware of the RX via visit 10.0.0.1 from the web browser(password: expresslrs)