A C++ library to interface with the Dragino LoRa Hat for Raspberry Pi. This board is based on the Semtech SX127[6789] chipset, and supports all global ISM bands. It also has an on-board GPS chipset based on the Mediatek MT3339 however this driver does not support its use. Communication is via SPI, using the wiringPi SPI library.
This chipset operates in both LoRa and FSK/OOK modes, however this driver supports only LoRa operation.
Note that all set() methods return this, so they can be chained.
/**
* Set up a LoRa instance
*
* Params:
* SPI_CHANNEL: The SPI channel to use. RasPi has two; 0 and 1
* SS_PIN: The SPI slave-select pin. The Dragino board uses pin 6.
* DIO0_PIN: The (interrupt-capable) DIO0 pin. Dragino uses pin 7.
* RST_PIN: The LoRa RESET pin. Dragino uses pin 0.
*/
LoRa lora(SPI_CHANNEL, SS_PIN, DIO0_PIN, RST_PIN);
/**
* bool begin()
* Initialise the LoRa radio.
* Params: none
* Returns: true if the radio chipset is recognised; false otherwise
*/
lora.begin();
/**
* LoRa setFrequency(freq) - set the carrier centre frequency, in Hz
* The LoRa class defines three constants for this purpose:
* - FREQ_433: 433 MHz
* - FREQ_868: 868.1 MHz
* - FREQ_915: 915 MHz
*/
lora.setFrequency(LoRa::FREQ_433);
/**
* LoRa setTXPower(power)
* Set the power amplifier transmit power, in dBm.
* Minimum: 2 dBm
* Maximum: 17 dBm normally; 20 dBm in boost mode (see setLNABoost())
*/
lora.setTXPower(17);
/**
* LoRa setSpreadFactor(sf)
* Set the radio spreading factor. High values maximise range and
* reliability; low values maximise bandwidth.
* The default is 7; acceptable values range from 6 to 12.
* The LoRa class defines constants SF_6 through SF_12.
*/
lora.setSpreadFactor(LoRa::SF_12);
/**
* LoRa setBandwidth(bw)
* Set the signal bandwidth in Hz
* The default is 125 kHz (BW_125k)
* Acceptable discreet values range from 7.8 kHz to 500 kHz (depending on
* the carrier frequency). The LoRa class defines the following acceptable
* values:
* BW_7k8, BW_10k4, BW_15k6, BW_20k8, BW_31k25,
* BW_41k7, BW_62k5, BW_125k, BW_250k, BW_500k
*/
lora.setBandwidth(LoRa::BW_125k);
/**
* LoRa setCodingRate(cr)
* Sets the radio's cyclic error coding rate. High values maximise
* reliability and error detection/correction, but incur a higher data
* overhead per transmission. Smaller values decrease the error
* correction in favour of data throughput. The LoRa class defines the
* following constants for this use:
* CR_45 (default), CR_46, CR_47, CR_48
*/
lora.setCodingRate(LoRa::CR_48);
/**
* LoRa setSyncWord(uint8_t)
* Sets the sync word (essentially an address) for the radio.
* Packets received with a matching sync word will be processed.
* A value of 0x34 is reserved for LoRaWAN networks. The default is 0x12.
*/
lora.setSyncWord(0x12);
/**
* LoRa setHeaderMode(hm)
* LoRa has two header modes - explicit (the default) and implicit.
* In explicit mode, a header is added to the packet containing the
* payload length, error coding rate, and CRC, which supports a variable
* packet length. If a fixed packet length is known (or spread factor 6
* is selected where implicit mode is mandatory) then the header can be
* omitted using implicit mode.
*/
lora.setHeaderMode(LoRa::HM_EXPLICIT);
/**
* LoRa enableCRC()
*/
lora.enableCRC();
See the sample applications in the examples folder.
- Code to receive transmissions in single-packet mode
- More examples
- Finish the documentation
- Tests!
Inspiration (and implementation hints) came from the Arduino LoRa library by Sandeep Mistry. Without a working reference implementation for testing, development of this library would scarcely have been possible.
This software is licensed under the MIT License.