SX1278

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Introduction

EX78 wireless front-end module, using high-performance, highly integrated RF transceiver chip SX1278 design and production.
Advanced LoRa spread spectrum communication technology to ensure that the module communication distance and anti-jamming capability greatly improved, and also do a very low current consumption.
In the LoRa mode, the EX78 offers higher reception sensitivity performance, stronger anti-jamming coding capability, and improved communication range and reliability compared to the same transmit and receive modules on the market. In the normal (G) FSK mode, can also provide the industry's products equivalent to the receiver sensitivity, and very high communication speed.
EX78 is a wireless module that supports powerful spread spectrum communication technology and low current consumption. It can be widely used in meter reading system, energy monitoring system, wireless industrial remote control, wireless data acquisition and control, wireless security Alarm, smart home and other fields.

Features

Main features

  • SPI Interface
  • central frequency 433mhz, or 470mhz
  • referencial distance 10KM
  • SX1278 IC, TTL output
  • Max power rate 20dbm, can be setup by software
  • 1.7-3.8V power supply

Specfication

  • Operating voltage: 1.8 ~ 3.7V
  • Receiving current: 10 ~ 14mA
  • Tranmission current:
  • 120 mA @ + 20 dBm
  • 90mA @ + 17dBm
  • 29mA @ + 13dBm
  • Operating frequency: 433MHz, 475MHz
  • Transmit power: +20 dBm
  • Receiver sensitivity:
  • -139dBm @ LoRaTM & 62.5Khz & SF = 12 & 146bps
  • -136 @ LoRaTM & 125Khz & SF = 12 & 293bps
  • -118 @ LoRaTM & 125Khz & SF = 6 & 9380bps
  • -123@FSK&5Khz&1.2Kbps
  • -117@FSK&5Khz&4.8Kbps
  • -110@FSK&20Khz&38.4Kbps
  • Frequency error: +/- 10ppm
  • FIFO space: 64 bytes
  • Data rate:
  • 1.2K~300Kbps@FSK
  • 0.018K ~ 37.5Kbps @ LoRaTM
  • Modulation: FSK, GFSK, MSK, GMSK, LoRaTM, OOK
  • Interface type: SPI
  • Sleep Current: 0.2uA@SLEEP, 1.5uA @ IDLE
  • Operating temperature: -40 ℃ ~ +85 ℃
  • Digital RSSI function
  • Automatic frequency correction
  • Automatic Gain Control
  • RF wake-up function
  • Low voltage detection and temperature sensors
  • Fast wake-up and frequency hopping
  • Highly configurable packet handlers
  • Antenna diversity and TX / RX switch control

Pin definition, size

Sx1278 pins.jpg
  • 1 GND - Negative power ground
  • 2 SO I SPI interface MISO data output
  • 3 SI O SPI interface MOSI data input
  • 4 SCK I SPI interface SCLK clock input
  • 5 NSS I SPI Interface NSS Select input
  • 6 RESET I Reset pin
  • 7 DIO5 I / O direct connect chip DIO5 digital I / O pin, software setting
  • 8 GND - Negative power ground
  • 9 RF I / O RF signal input / output, connected to 50Ω antenna
  • 10 GND - Negative power ground
  • 11 DIO3 I / O direct connect chip DIO3 digital I / O pin, software setting
  • 12 DIO4 I / O direct connect chip DIO4 digital I / O pin, software setting
  • 13 VCC - positive power supply 1.8 ~ 3.7V
  • 14 DIO0 I / O direct connect chip DIO0 digital I / O pin, software setting
  • 15 DIO1 I / O direct connect chip DIO1 digital I / O pin, software setting
  • 16 DIO2 I / O Direct Connect DIO2 Digital I / O pin, software setting

Application

  • Use with atmega48 IC
Sx1278 application schematic.jpg

Use

Wakeup Sequency

  • Note: Why there is only one switch on board, has one transistor missed?

SMETECH factory recommended application circuit, RF switch selection is PE4259, we are using the model. SX1278 chip 20PIN control PE4259 4PIN, to achieve automatic switching transceiver. Mainly PE4259 function than ordinary RF switch powerful, the use of ordinary RF switch, you need to add a transistor in the circuit board in order to achieve automatic switching transceiver or CPU / SX1278 two GPIO to control the general RF switch tube Two I / O, to achieve transceiver switch (but not automatically switch). In order to reduce the on-board components, 16 * 16mm PCBA area reserved on the location of the shield, so choose this higher price of PE4259 RF switch design circuit. PE4259 than ordinary RF switch you about 3 to 5 times.

Documents

Demo code