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https://github.com/martynwheeler/u-lora

raspi-lora for micropython
https://github.com/martynwheeler/u-lora

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raspi-lora for micropython

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# u-lora



This is a port of raspi-lora (https://pypi.org/project/raspi-lora/) for micropython.  I have tested on raspberry pi pico, esp8266, and esp32.  It allows your microcontroller to use an RFM95 radio to communicate.



## Wiring



The pinout for the RFM95 module can be found on page 10 of the documentation (https://cdn.sparkfun.com/assets/learn_tutorials/8/0/4/RFM95_96_97_98W.pdf).  The pin numbers below are for the RFM95 - look at your microcontroller docs for the pins to connect to them.



Power (the RFM95 module requires 3.3V from your microcontroller):  

+ connect 3.3V to pin 13  

+ connect GND to pin 1, 8, or 10 on the RFM95 module



For SPI communication:  

+ MISO to pin 2 (MISO)  

+ MOSI to pin 3 (MOSI)  

+ SCK to pin 4 (SCK)  

+ CS to pin 5 (NSS)  

    

Other pins:  

+ Use a GPIO output to pin 6 (RESET) for resetting the RFM95  

+ Use a GPIO input to pin 14 (D) to trigger that a message has been received  



## Configuration

**INITIALIZATION**

```

LoRa(spi_channel, interrupt, this_address, cs_pin, reset_pin=None, freq=868, tx_power=14,

    modem_config=ModemConfig.Bw125Cr45Sf128, acks=False, crypto=None)

```



**spi_channel** SPI channel, check SPIConfig for preconfigured names, e.g. SPIConfig.rp2_0 for RPi pico channel 0   

**interrupt** GPIO pin to use for the interrupt  

**this_address** The address number (0-254) your device will use when sending and receiving packets.  

**cs_pin** chip select pin from microcontroller  

**reset_pin** : the GPIO used to reset the RFM9x if connected  

**freq** Frequency used by your LoRa radio. Defaults to 868Mhz  

**tx_power** Transmission power level from 5 to 23. Keep this as low as possible. Defaults to 14  

**modem_config** Modem configuration. See RadioHead docs. Default to Bw125Cr45Sf128.  

**receive_all** Receive messages regardless of the destination address  

**acks** If True, send an acknowledgment packet when a message is received and wait for an acknowledgment when transmitting a message. This is equivalent to using RadioHead's RHReliableDatagram  

**crypto** An instance of PyCryptodome Cipher.AES (not tested) - should be able to use ucrypto  



### SPICONFIG

Preconfigured SPI bus pins for tested devices, just add into the class for other devices

```

class SPIConfig():

    # spi pin defs for various boards (channel, sck, mosi, miso)

    rp2_0 = (0, 6, 7, 4)

    rp2_1 = (1, 10, 11, 8)

    esp8286_1 = (1, 14, 13, 12)

    esp32_1 = (1, 14, 13, 12)

    esp32_2 = (2, 18, 23, 19)

```



### ModemConfig

Preconfigured modem settings taken from Radiohead docs, I will try and add the ability to fine tune these in future.

```

    Bw125Cr45Sf128 = (0x72, 0x74, 0x04) #< Bw = 125 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Default medium range

    Bw500Cr45Sf128 = (0x92, 0x74, 0x04) #< Bw = 500 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Fast+short range

    Bw31_25Cr48Sf512 = (0x48, 0x94, 0x04) #< Bw = 31.25 kHz, Cr = 4/8, Sf = 512chips/symbol, CRC on. Slow+long range

    Bw125Cr48Sf4096 = (0x78, 0xc4, 0x0c) #/< Bw = 125 kHz, Cr = 4/8, Sf = 4096chips/symbol, low data rate, CRC on. Slow+long range

    Bw125Cr45Sf2048 = (0x72, 0xb4, 0x04) #< Bw = 125 kHz, Cr = 4/5, Sf = 2048chips/symbol, CRC on. Slow+long range

```



## Examples

There are two examples to test sending and receiving data in the examples folder



### Server mode:



Copy the file server.py to your main.py and copy it across together with the library ulora.py to your microcontroller



```

from time import sleep

from ulora import LoRa, ModemConfig, SPIConfig



# This is our callback function that runs when a message is received

def on_recv(payload):

    print("From:", payload.header_from)

    print("Received:", payload.message)

    print("RSSI: {}; SNR: {}".format(payload.rssi, payload.snr))



# Lora Parameters

RFM95_RST = 27

RFM95_SPIBUS = SPIConfig.rp2_0

RFM95_CS = 5

RFM95_INT = 28

RF95_FREQ = 868.0

RF95_POW = 20

CLIENT_ADDRESS = 1

SERVER_ADDRESS = 2



# initialise radio

lora = LoRa(RFM95_SPIBUS, RFM95_INT, SERVER_ADDRESS, RFM95_CS, 

            reset_pin=RFM95_RST, freq=RF95_FREQ, tx_power=RF95_POW, acks=True)



# set callback

lora.on_recv = on_recv



# set to listen continuously

lora.set_mode_rx()



# loop and wait for data

while True:

    sleep(0.1)

```



### Client mode:

Copy the file server.py to your main.py and copy it across together with the library ulora.py to your microcontroller



```

from time import sleep

from ulora import LoRa, ModemConfig, SPIConfig



# Lora Parameters

RFM95_RST = 27

RFM95_SPIBUS = SPIConfig.rp2_0

RFM95_CS = 5

RFM95_INT = 28

RF95_FREQ = 868.0

RF95_POW = 20

CLIENT_ADDRESS = 1

SERVER_ADDRESS = 2



# initialise radio

lora = LoRa(RFM95_SPIBUS, RFM95_INT, CLIENT_ADDRESS, RFM95_CS,

            reset_pin=RFM95_RST, freq=RF95_FREQ, tx_power=RF95_POW, acks=True)



# loop and send data

while True:

    lora.send_to_wait("This is a test message", SERVER_ADDRESS)

    print("sent")

    sleep(10)

```