LoRa Daughter Board

_images/internal_antenna.jpg

Description

LoRa is a radio technology that enables sending short data packets over a long range (generally kilometers). The LoRa daughter board is designed around the HopeRF RFM95W LoRa-enabled radio module. An FPC antenna (915/868 MHz) makes the board handy and easy to carry anywhere. For users who want more range, an external antenna can be added using the included U.fl connector.

The LoRa daughter board is powered directly from the WiPhone mainboard which means you don't need any external power connections. Just install the daughter board on the back of a WiPhone and you are ready to send data packets.

Features

  • Uses the license-free ISM bands: "European ISM" @ 868MHz or "American ISM" @ 915MHz
  • 915/868MHz FPC antenna. U.fl connector for external antenna.
  • +5 to +20 dBm up to 100 mW Power Output Capability (power output selectable in software)
  • ~100mA peak during +20dBm transmit, ~30mA during active radio listening.
  • Range of approx. 2Km, depending on obstructions, frequency, antenna and power output. (For more info please visit LoRa Range Testing Results)

Technical Details

_images/LoRa_Board_Pinout_v2-01.png
DB Pin # Pin Name Arduino/Extender Pin Description
14 3.3V   3.3V Power Supply for RFM95W LoRa Module.
2,11,13 GND   This pin is connected to System GND.
3 Interrupt 38 Interrupt pin for RFM95W module
7 MISO 12 RFM95W SPI Data output .
8 MOSI 13 RFM95W SPI Data input .
10 SCK 14 RFM95W SPI Clock input .
9 NSS 27 RFM95W SPI Chip select input .
4 DIO1 32 RFM95W Digital I/O, software configured .
15 Reset EXTENDER_PIN(10) RFM95W Reset input .
17 DIO2 EXTENDER_PIN(12) RFM95W Digital I/O, software configured .

Hardware Overview

_images/LoRa_legends.png

HoPeRF RFM95W

_images/RFM95W.png

The RFM95W transceivers (868 or 915 MHz) feature the LoRaTM long range modem that provides ultra-long range spread spectrum communication and high interference immunity whilst minimizing current consumption.

For further detail Please refer to HopeRF Website .

FPC Antenna

_images/FPCantenna.png
  • Frequency: 824-960Mhz
  • Impedance: 50 Ohm
  • S.W.R <= 1.5
  • Polarization: Linear
  • Gain: 5dbi
  • Size: 51x16x0.2mm
  • Connector: ipex1 connector

Software Overview

By default, LoRa daughterboard support is turned ON in firmware. To disable LoRa board with the WiPhone firmware, comment #define LORA_MESSAGING in config.h

image10

The LoRa board pin definitions and configuration can be seen in code below.

Hardware.h:

334
335
336
337
338
339
340
341
342
343
#define RFM95_RST     -1
#define RFM95_CS      27
#define RFM95_INT     38

#define HSPI_MISO   12
#define HSPI_MOSI   13
#define HSPI_SCLK   14
#define HSPI_SS     27

#define RF95_FREQ 915.0

Note

Make sure your entered correct frequency (915 or 868) as per your hardware, you can change the frequency with #define RF95_FREQ 915.0 (see Warning below).

Warning

Setting wrong frequency may result in degraded performance and poor range. In worse scenario it may damage your hardware.

For LoRa Daughter Boards communication we are using RadioHead Library version=1.112.

In order to get RadioHead library working with WiPhone firmware, We had to slightly change the library so that it can use the SPI bus assign to Daughter Board connector.

lora.cpp:

23
24
25
26
27
28
29
30
31
32
void Lora::setup() {
log_i("Initializing LoRa: %d", ESP.getFreeHeap());
loraSPI = new RHSoftwareSPI();
rf95 = new RH_RF95(RFM95_CS, RFM95_INT, *loraSPI);

loraSPI->setPins(HSPI_MISO, HSPI_MOSI, HSPI_SCLK);
pinMode(RFM95_RST, OUTPUT);
rf95->init();
rf95->setFrequency(RF95_FREQ);
rf95->setTxPower(23, false);

LoRa Contacts and Messages

LoRa Contacts

To send LoRa messages you'll first need to enter the recipient's LoRa address into your contacts:

  • Select Menu > phonebook Phonebook > Add.
  • Write the name of the contact in Name field. The name is only required for distinguishing contacts and can be anything easy for you to remember.
  • Enter the LoRa address in the LoRa address field.
  • Press the Save soft key to save the contact.

s5 s6 s7

Note

To find your LoRa address, select Menu > Tools > Development > Diagnostics. The last 6 digits of your MAC address are your LoRa address. image9

LoRa Messages

  • Select Menu > message Message > newmessage New Message.
  • Enter the address of the recipient in the To field and select the option LoRa and enter the message text in the Message field.
  • Press the Send soft key to send the message.

s8 s10

OR

  • Select Menu > phonebook Phonebook > Select Contact.
  • Select Send Message and select the option LoRa and enter the message text.
  • Press the Send soft key to send message.

s11 s10

Note

Character limit for LoRa messaging is set to 230 characters in firmware.