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Nie, dziękuję Przekieruj mnie tamI have a DX-LR02 connected to a dx-pj15-v1.1 I want it to send temperature readings from my garage, which is 500 feet away. How do I set up the device and program it?
• You need two DX-LR02 LoRa radios – one in the garage and one in the house – plus a small micro-controller to read the temperature sensor in the garage.
• Configure both radios with identical LoRa parameters (frequency, spreading factor, bandwidth, network-ID, UART speed) over the DX-PJ15-V1.1 USB-TTL adapter using simple AT commands.
• Wire the garage radio to the micro-controller, connect a temperature sensor (e.g., DS18B20), and run a short sketch that reads the sensor and writes an ASCII string to the radio every minute.
• At the house end connect the second radio to a micro-controller or directly to the DX-PJ15-V1.1 + PC; whatever arrives on its UART is the temperature text sent from the garage.
• With modest 3–5 dBi whip antennas, SF 10-12, and 22 dBm output, 500 ft (≈150 m) is well inside the link budget even through typical garage and house walls.
Hardware roles
• DX-LR02 – pure LoRa transceiver with an AT-command UART interface (Semtech SX1276/SX1278 inside).
• DX-PJ15-V1.1 – CH340-based USB-TTL board used for (a) configuring the LR02, or (b) flashing / talking to the micro-controller.
• Micro-controller – any 3.3 V device with a spare UART: Arduino Nano/Pro Mini (3.3 V), ESP32, STM32, etc.
• Temperature sensor – robust, digital, and long-cable-friendly → DS18B20 (1-Wire) is the usual choice.
Minimum component list
– 2 × DX-LR02
– 2 × 3–5 dBi antennas cut for the module’s band (433 / 868 / 915 MHz – printed on the can)
– 1 × micro-controller plus DS18B20 in the garage
– (Optional) 2nd micro-controller in the house, or simply a PC running a terminal
– One DX-PJ15-V1.1 (you can time-share it for configuration and programming)
Wiring example (Arduino Nano Every, 3.3 V version)
┌──────── Garage Node ────────┐ │Nano ↔ DX-LR02 │ │ D9 → RXD (module) │ │ D8 ← TXD │ │ 3V3 ↔ VCC │ │ GND ↔ GND │ │ │ │DS18B20 DATA → D4 (4.7 kΩ pull-up to 3V3)│ │DS18B20 VCC → 3V3, GND → GND │ └─────────────────────────────┘
Receiver wiring is identical, or plug the module into DX-PJ15 and open a serial terminal at the configured baud rate.
Radio configuration (AT commands, 9600 baud by default)
Connect the LR02 to DX-PJ15, open PuTTY/Arduino Serial Monitor at 9600 8 N 1, and issue:
AT+FREQ=915000000 # 915 MHz US; use 868 MHz EU or 433 MHz AS
AT+PARAMETER=12,7,1,4 # SF12, 125 kHz BW, CR 4/5, preamble 4
AT+ADDRESS=1 # garage node
AT+NETWORKID=7
AT+CRFOP=22 # 22 dBm (legal ISM max in US)
AT+UART=9600,8,1,0,0 # 9600 N 8 1
AT+SAVERepeat for the house unit, only change ADDRESS to 2.
Both radios must share FREQ, PARAMETER, NETWORKID, UART.
#include <SoftwareSerial.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#define LORA_RX 8 // from LR02 TXD
#define LORA_TX 9 // to LR02 RXD
#define ONE_WIRE 4
SoftwareSerial lora(LORA_RX, LORA_TX); // 9600-baud UART to LR02
OneWire oneWire(ONE_WIRE);
DallasTemperature sensors(&oneWire);
void setup() {
Serial.begin(115200);
lora.begin(9600); // must match AT+UART
sensors.begin();
}
void loop() {
sensors.requestTemperatures();
float t = sensors.getTempCByIndex(0);
if (t != DEVICE_DISCONNECTED_C) {
char buf[16]; // "23.4"
dtostrf(t, 4, 1, buf);
lora.print("AT+SEND=2,"); // dest addr, length follows
lora.print(strlen(buf));
lora.print(",");
lora.println(buf); // LR02 ends packet on CR/LF
Serial.print("Sent "); Serial.println(buf);
}
delay(60000); // 1-min interval
}House (receiver) options
a) Plug LR02 into DX-PJ15, open terminal; strings like Temp:23.4 will scroll every minute.
b) Use second MCU; any bytes arriving on its UART can be sent to LCD, MQTT, InfluxDB, etc.
Link-budget sanity for 500 ft
SF12, BW 125 kHz, 22 dBm Tx, 0 dBi Rx antenna:
• Link budget ≈ 22 dBm – (–140 dBm sensitivity) = 162 dB.
• Free-space loss at 915 MHz, 150 m ≈ 81 dB.
Leaves > 80 dB margin – enough for two walls and foliage. Reduce to SF10 (~148 dB) for faster packets if margin allows.
• Most hobby projects today replace the discrete LR02 + µC pair with a LoRa-WAN capable ESP32-SX1276 combo board (Heltec, LilyGo T-Beam). Same wiring but SPI rather than AT-UART, deeper sleep modes (<10 µA) and native MQTT via Wi-Fi when in range.
• Semtech’s new LR-FSS (FiFo Spread Spectrum) / LoRa-Edge line (LR1120) adds multi-band GNSS and Wi-Fi sniffing for asset-tracking – promising for future garage sensors needing location or power harvesting.
• Regulators are tightening duty-cycle limits (e.g., ETSI EN300-220 1 % or 0.1 %) – stick to sub-second packets every few minutes to stay compliant.
• Why AT commands? The LR02 already wraps the SX127x radio with a small MCU; you avoid SPI and the RadioHead/LoRa libraries.
• Why DS18B20? Long cable, 9-12-bit resolution, only one pull-up resistor, tolerant of 3.0 – 5.5 V.
• Power: garage node typically <25 mA during Tx, <2 mA idle. Add deep-sleep to reach <100 µA average if battery-powered.
• Antenna height matters more than gain; 1 m above roof-line can double range vs. inside wall mounting.
• Operate within ISM band limits (433 / 868 / 915 MHz) and regional EIRP caps (e.g., 30 dBm ERP for US 915 MHz, 14 dBm for EU 868 MHz unless LBT/AFA implemented).
• Do not exceed duty-cycle regulations; periodic temp telemetry is fine.
• If personal data (e.g., occupancy) is added later, consider encryption (LoRa supports AES128) to protect privacy.
• Configure both radios on the bench first; verify packets at 1 m before mounting.
• Label each module with its ADDRESS to avoid swapping later.
• Use heat-shrink or weatherproof boxes; condensation in garages is the #1 field failure.
• If serial “garbage” appears, mismatch in UART baud or newline mode – reissue AT+UART?.
• Keep sensor cable away from motor inrush currents (garage opener) or use shielded CAT-5.
• The DX-LR02’s AT firmware revisions differ; some use AT+CRFOP, some AT+POWER. Run AT+VERSION to see which syntax applies.
• Range estimates assume no metal siding. Steel roofs reduce RSSI ≈ 10 dB; add external antenna or higher SF.
• Long USB leads to the DX-PJ15 may pick up RF; use ferrite or keep under 1 m.
• Experiment with LoRa-WAN gateways (TTN) – you can feed the same sensor to cloud dashboards without changing RF hardware (requires LMIC-based firmware).
• Test chirp-stack or Helium if you later need miles-wide coverage.
• Compare DS18B20 vs. SHT-30 (temp + humidity) for HVAC projects.
• Read Semtech AN1200.22 for deep dive into SF/BW/Coding-rate vs. link budget.
Set up a pair of DX-LR02 radios with matching frequency and network settings via DX-PJ15.
Attach one to a 3.3 V micro-controller in the garage along with a DS18B20, flash a simple sketch that sends a formatted string over UART every minute.
Place the second radio in your house on the same UART settings; anything it prints is your temperature reading.
With proper antennas and SF10-12 the 500-ft hop is straightforward, while staying within legal ISM limits and leaving room for battery operation, encryption, or future LoRa-WAN migration.