Examples in this section demonstrate a simple LoRaWAN Relay application.
sensor_to_relay_example sends a "Hello world" LoRaWAN packet with 1-second extended preamble length every TX_INTERVAL seconds.
relay_example continuously listens for LoRaWAN packets from sensors (or other LoRaWAN device) & prints packet information to Serial Monitor if it's successfully received. This sketch is NOT included packet integrity check, packet sender address filter, and repeat the received packet.
This sketch is basically a LoRaWAN ABP example with the extended preamble length. All functions to modify LoRaWAN parameters are the same as this #lorawan_abp_example section. The extended preamble length can be enable with the following function:
sx126x.set_send_to_relay(true);
The relay receives only packets from devices/sensors that matches LoRaWAN parameters. Listening LoRaWAN parameters is listed in a struct rft_lora_params_t relay_lora_params as follow:
relay_lora_params.frequency = 866600000;
relay_lora_params.spreading_factor = RFT_LORA_SPREADING_FACTOR_7;
relay_lora_params.bandwidth = RFT_LORA_BANDWIDTH_125KHZ;
relay_lora_params.coding_rate = RFT_LORA_CODING_RATE_4_5;
relay_lora_params.syncword = RFT_LORA_SYNCWORD_PUBLIC;
This struct rft_lora_params_t relay_lora_params is put into relay function later. This relay function is a blocking function. It's looped infinitely until detect a preamble (Channel Activity Detection).
sx126x.relay(&relay_lora_params, payload, payload_len, NULL, NULL);
The relay's Channel Activity Detection can be modified to archive higher successful reception rate or lower power consumption. It's highly recommended to NOT change these following paramters for best tested relay performance (measured by RFThings).
relay_lora_params.relay_sleep_interval_us = 1E6; // 1 second
relay_lora_params.relay_rx_symbol = 5;
relay_lora_params.relay_max_rx_packet_length = 120;
void set_send_to_relay(bool _send_to_relay);
| Parameter | Value | Description |
|---|---|---|
| _send_to_relay | true / false | Enable 1-second extended preamble length |
rft_lora_params_t relay_lora_params;
| Parameter | Data type | Description |
|---|---|---|
| relay_lora_params.frequency | uint32_t | The TX frequency in Hz |
| relay_lora_params.spreading_factor | rft_lora_spreading_factor_t | LoRa Transmit Spreading Factor |
| relay_lora_params.bandwidth | rft_lora_bandwidth_t | LoRa Transmit Bandwidth |
| relay_lora_params.coding_rate | rft_lora_coding_rate_t | LoRa Transmit Coding Rate |
| relay_lora_params.syncword | rft_lora_syncword_t | LoRa Transmit Syncword |
| relay_lora_params.send_to_relay | bool | LoRa Transmit Syncword |
| relay_lora_params.relay_sleep_interval_us | uint32_t | Sleep interval between 2 wakeup windows |
| relay_lora_params.relay_rx_symbol | uint8_t | The number of receive symbols to detect packet incoming in each wakeup windows |
| relay_lora_params.relay_max_rx_packet_length | uint8_t | The maximum number of receive packet length in byte(s) |
Details on value of each member of the struct are listed as follow:
| Parameter | Value | Description |
|---|---|---|
| relay_lora_params.spreading_factor | RFT_LORA_SPREADING_FACTOR_5 | Spreading Factor 5 |
| relay_lora_params.spreading_factor | RFT_LORA_SPREADING_FACTOR_6 | Spreading Factor 6 |
| relay_lora_params.spreading_factor | RFT_LORA_SPREADING_FACTOR_7 | Spreading Factor 7 |
| relay_lora_params.spreading_factor | RFT_LORA_SPREADING_FACTOR_8 | Spreading Factor 8 |
| relay_lora_params.spreading_factor | RFT_LORA_SPREADING_FACTOR_9 | Spreading Factor 9 |
| relay_lora_params.spreading_factor | RFT_LORA_SPREADING_FACTOR_10 | Spreading Factor 10 |
| relay_lora_params.spreading_factor | RFT_LORA_SPREADING_FACTOR_11 | Spreading Factor 11 |
| relay_lora_params.spreading_factor | RFT_LORA_SPREADING_FACTOR_12 | Spreading Factor 12 |
| Parameter | Value | Description |
|---|---|---|
| relay_lora_params.bandwidth | RFT_LORA_BANDWIDTH_10KHZ | Bandwidth 10.42 kHz |
| relay_lora_params.bandwidth | RFT_LORA_BANDWIDTH_15KHZ | Bandwidth 15.63 kHz |
| relay_lora_params.bandwidth | RFT_LORA_BANDWIDTH_20KHZ | Bandwidth 20.83 kHz |
| relay_lora_params.bandwidth | RFT_LORA_BANDWIDTH_31KHZ | Bandwidth 31.25 kHz |
| relay_lora_params.bandwidth | RFT_LORA_BANDWIDTH_41KHZ | Bandwidth 41.67 kHz |
| relay_lora_params.bandwidth | RFT_LORA_BANDWIDTH_62KHZ | Bandwidth 62.50 kHz |
| relay_lora_params.bandwidth | RFT_LORA_BANDWIDTH_125KHZ | Bandwidth 125 kHz |
| relay_lora_params.bandwidth | RFT_LORA_BANDWIDTH_250KHZ | Bandwidth 250 kHz |
| relay_lora_params.bandwidth | RFT_LORA_BANDWIDTH_500KHZ | Bandwidth 500 kHz |
| Parameter | Value | Description |
|---|---|---|
| relay_lora_params.coding_rate | RFT_LORA_CODING_RATE_4_5 | Coding Rate 4/5 |
| relay_lora_params.coding_rate | RFT_LORA_CODING_RATE_4_6 | Coding Rate 4/5 |
| relay_lora_params.coding_rate | RFT_LORA_CODING_RATE_4_7 | Coding Rate 4/5 |
| relay_lora_params.coding_rate | RFT_LORA_CODING_RATE_4_8 | Coding Rate 4/5 |
| Parameter | Value | Description |
|---|---|---|
| relay_lora_params.syncword | RFT_LORA_SYNCWORD_PRIVATE | Private Network Syncword (0x1424) |
| relay_lora_params.syncword | RFT_LORA_SYNCWORD_PUBLIC | Public Network Syncword (0x3444) |
rft_status_t relay(rft_lora_params_t *relay_lora_params, byte *payload, uint32_t &payload_len, void (*rx_func)(void), void (*sleep_func)(void));
| Parameter | Description |
|---|---|
| relay_lora_params | Pointer to the rft_lora_params_t struct of LoRa configuration that the sender device |
| payload | Pointer to the received packet buffer |
| payload_len | The received packet length |
| rx_func | Pointer to the receiving function. This function will be invoke before wakeup windows. It's normally used for setup RF Switch or Front-End. |
| sleep_func | Pointer to the Micro-controller sleep function. If this is not NULL, the Micro-controller is in sleep mode until then relay function return. |
| Return value | Description |
|---|---|
| RFT_STATUS_OK | Packet received successfully |
| RFT_STATUS_PREAMBLE_DETECT_FAIL | Preamble detected but not detect Syncword |
| RFT_STATUS_RX_TIMEOUT | Preamble & Syncword detected but Receiving takes too long |