PP RX was designed by @Jye Smith of the ExpressLRS development team. Its main hardware architecture is STM32L432KBU6 MCU and SX1280 RF chip. It has a built-in ceramic antenna, which is ultra-light and small.
Based on PP RX, we developed the ESP8285 version of Nano 2.4GHz rx, named EP1 and EP2. The RF module of EP1/EP2 is the same as PP RX, but it uses ESP8285 MCU. Therefore, you can upgrade the firmware via WIFI, which is very user-friendly. To flash the firmware, Power up the receiver while keeping the transmitter turned off. After a while, you can find the ExpressLRS hotspot. Connect to this hotspot using a PC or mobile phone. The password is expresslrs, then you can visit 10.0.0.1 to upload the firmware.

Binding steps:
1. After the receiver is connected to the flight controller, power the FC through USB connection. Disconnect it as soon as the LED on the receiver turns off. Repeat the procedure one more time. when the USB is connected for the third time, the LED will start to flash double, which means that the receiver enters the bingding mode.
2. After the ES24TX module or other 2.4G ELRS module are properly installed on your transmitter, copy the ELRS.LUA file to the "SD Card/Scripts/tools" directory in the SD card of the radio, then run ELRS.LUA to continue Bind procedure .
3. After the binding is successful, the LED on the receiver will go steady.

ESP8285 processor
SX1280IMLTRT wireless radio frequency module
2.4GHz omnidirectional T antenna
Frequency range: 2400 MHz to 2500 MHz
Maximum receiving refresh rate: 500Hz
Minimum receiving refresh rate: 25Hz
Working voltage: 5v
Weight: 0.42g (without antenna)
Size: 10mm*10mm*3mm Working protocol: CRSF (Betaflight)
Peak gain: 2.23dB
Packing: EP1_RX receiver x1
40MM antenna x1
90MM antenna x1