4 years, 3 months ago.

915MHz frequency band for North America

How do I configure the LoRa transmitter to the 915MHz frequency band for North America?

The main.cpp page has the following code. I changed the RF_FREQUENCY to 915000000 Hz but didn't get an operational link in the ping-pong application.

/* Set this flag to '1' to use the LoRa modulation or to '0' to use FSK modulation */

  1. define USE_MODEM_LORA 1
  1. define RF_FREQUENCY 868000000 Hz
  2. define TX_OUTPUT_POWER 14 14 dBm
  1. if USE_MODEM_LORA == 1
  1. define LORA_BANDWIDTH 2 [0: 125 kHz, 1: 250 kHz, 2: 500 kHz, 3: Reserved]
  2. define LORA_SPREADING_FACTOR 7 [SF7..SF12]
  3. define LORA_CODINGRATE 1 [1: 4/5, 2: 4/6, 3: 4/7, 4: 4/8]
  4. define LORA_PREAMBLE_LENGTH 8 Same for Tx and Rx
  5. define LORA_SYMBOL_TIMEOUT 5 Symbols
  6. define LORA_FIX_LENGTH_PAYLOAD_ON false
  7. define LORA_FHSS_ENABLED false
  8. define LORA_NB_SYMB_HOP 4
  9. define LORA_IQ_INVERSION_ON false
  10. define LORA_CRC_ENABLED true

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1 Answer

4 years, 3 months ago.

Hello Tom, What embedded system platform are you using? If you are using Keil uVision, you can manually enter the frequency under preprocessor settings.

Under Project, click on ‘Options for Target sx1272mb2das’. Click on C/C++ and in the field ‘Define’ update the frequency band as 915, in the format REGION_US915. Click OK.

Let me know if this works.

Accepted Answer

I don't have the Keil uVision. I was using the online mBED IDE to edit the files and compile. I immediately tried editing the above line: "define RF_FREQUENCY 868000000 Hz" to 915000000 Hz It compiled and uploaded but it didn't appear to get the Ping-Pong application connecting. SO I wonder if there are other changes required to make this compatible. My next move is to connect to a Multitech LoRa receiver in Class A mode - but it must be 915MHz.

posted by Tom Burgmann 01 Nov 2017

Hi Tom, This is a preprocessor setting. You need to define the band in the IDE. Atleast that’s what I remember from my project. Did you go through the User manual??

posted by Azim Malik Abdul Aziz 01 Nov 2017