IntermediateWireless Communication
nRF24L01 Wireless Sensor Link
Send a small sensor reading between two microcontroller boards over a low-cost 2.4 GHz radio link.
Parts from the database
- NRF24L01 × 2One radio per node
- Raspberry-Pi-Pico × 2One microcontroller per node
- DHT22 × 1Optional sensor on transmitter
Other supplies
- two 3.3 V-compatible radio breakoutsCommon build supply
- two Pico boardsCommon build supply
- 10–47 µF capacitor at each radio supplyCommon build supply
- USB cablesCommon build supply
- jumper wiresCommon build supply
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Connections
- For each node, connect radio VCC to 3V3 only, GND to GND, SCK to GP18, MISO to GP16, MOSI to GP19, CE to GP17, and CSN to GP20.
- Place a 10–47 µF electrolytic capacitor close to each module's VCC/GND.
- Use distinct transmitter/receiver addresses and matching channel/data-rate settings in both sketches.
Build steps
- Install the RF24 library and run its GettingStarted example with the radios close together.
- Confirm one board can transmit and the other reports packets before adding sensors.
- Add a compact struct with the reading and a sequence number; check the receiver's packet status.
- Move the nodes apart gradually and record where packets become unreliable in your space.
Software and firmware setup
Firmware is required on both Pico boards, but the two-node application sketches are not included yet. Configure both radios with identical addresses, channel, data rate, and payload structure; add the optional DHT22 only after basic packets work.
Test your build
The receiver should display changing packets. Range varies with antenna, module version, obstructions, and radio interference; do not assume a fixed range.
Troubleshooting
- If radios are not detected, verify SPI pin mapping and use 3.3 V power.
- If packets drop, add supply decoupling and test at short range before adjusting radio settings.
- Do not use a high-power PA/LNA radio module without checking its supply-current needs.
Safety and limitations
Use certified low-power modules and follow local radio rules. Never connect a 5 V SPI signal directly to a 3.3 V radio.
Manufacturer and platform documentation
Community Notes for This Project
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