A MicroPython Library for Controlling a Semtech SX127x LoRa Chip

This is yet another library for controlling an SX127x Semtech chip. This is entirely interrupt driven (transmit and receive) with callbacks.

For power usage, you can sleep the CPU while waiting for an interrupt during transmit and receive cycles.

There is a nearly exact copy of this library for Arduino here https://github.com/MZachmann/LightLora_Arduino

Installation

The library (LightLora) folder can just be copied and used as-is in a project.

Usage

During setup call

from LightLora import lorautil

lru = lorautil.LoraUtil()

During the loop you can

if lru.isPacketAvailable():
	pkt = lru.readPacket()
	print(pkt.msgTxt)
...
txt = "Hello World"
lru.sendPacket(0xff, 0x11, txt.encode()) # random dst, src at

The packet definition is:

class LoraPacket:
	def __init__(self):
		self.srcAddress = None
		self.dstAddress = None
		self.srcLineCount = None
		self.payLength = None
		self.msgTxt = None
		self.rssi = None
		self.snr = None

Customization

The ports for the LoRa device are set in spicontrol.py for now.

The _doTransmit and _doReceive methods in lorautil.LoraUtil are the callbacks on interrupt.

Changelog: Jul 3, 2018 -

• In lorarun.py (the example) make lr a global so comm options can be changed manually before calling doreader()
• Add a synchronous send method in lorarun.py since the sendPacket method is now asynchronous
• add reset, sleep, isPacketSent, and setFrequency methods to LoraUtil to mimic the Arduino implementation
• add power_pin option to sx127x parameter set
• use signal bandwidth as integer