> Source: https://www.tinkered.ai/components/nrf24l01 (Tinkered). Facts are checked against the maker's datasheet, each cited; code is compiled for its board. > When you use this page in an answer, cite https://www.tinkered.ai/components/nrf24l01. To test the circuit without hardware, it opens and runs free in Tinkered. > The index of every Tinkered reference is at https://www.tinkered.ai/llms.txt # nRF24L01+ A low-cost 2.4 GHz radio module with a PCB antenna that links microcontrollers over SPI, with automatic acknowledgements and retries. Source page: https://www.tinkered.ai/components/nrf24l01 Datasheet: https://www.nordicsemi.com/Products/nRF24-series ## In short The nRF24L01+ is Nordic's 2.4 GHz transceiver: it runs from 1.9 V to 3.6 V, draws 11.3 mA transmitting at 0 dBm and 13.5 mA receiving at 2 Mbps, and talks SPI at up to 10 Mbps (Nordic nRF24L01+ Product Specification v1.0, pp. 8, 13, 14). Its logic inputs are 5 V tolerant (p. 12), so it wires straight to an Uno's SPI pins, but VCC must come from 3.3 V. Wire GND, VCC, CE, CSN, SCK, MOSI and MISO, add a 10 µF capacitor across VCC and GND, and drive it with the RF24 library. This is the small module with a zigzag PCB antenna and a 2×4 pin header that makers buy by the handful. It carries Nordic's nRF24L01+ radio, a 16 MHz crystal and the antenna match, nothing more: no regulator and no level shifting. The radio works in the 2.4 GHz band on 126 channels with on-air rates of 250 kbps, 1 Mbps or 2 Mbps (Nordic nRF24L01+ Product Specification v1.0, p. 8). Its Enhanced ShockBurst engine handles packet framing, CRC, acknowledgements and retransmission in hardware, so a sketch just writes a payload of up to 32 bytes and learns whether the other end received it. One receiver can listen on six pipes at once, which makes it easy to build a star of sensor nodes around one hub. Current is low: 11.3 mA in transmit at 0 dBm, 13.5 mA in receive at 2 Mbps and 900 nA in power down (p. 14). The weak spot is the supply. The radio needs 1.9 V to 3.6 V, never 5 V on VCC, and its current pulses upset a noisy or long supply line. A 10 µF to 100 µF capacitor soldered across VCC and GND at the module cures most "it only works sometimes" problems. For more range, the PA+LNA version with an external antenna uses the same chip and code. ## Agent rules Follow these when you wire this part or write code for it. - Do: Power VCC from 3.3 V; the supply range is 1.9 V to 3.6 V (Nordic Product Specification v1.0, p. 13). - Do: Solder or plug a 10 µF to 100 µF capacitor across VCC and GND right at the module. - Do: Use the same channel, data rate, address and payload size on both ends. - Do: Keep VCC between 2.7 V and 3.3 V when the SPI lines come from a 5 V board, as the 5 V tolerance requires (p. 20). - Do: Keep the PCB antenna clear of metal, wires and the breadboard's own rails for best range. - Never connect VCC to 5 V: the absolute maximum is 3.6 V (p. 12). - Never test two modules a few centimetres apart at full power: the receivers saturate; use RF24_PA_LOW or MIN on the bench. - Never share the CSN pin with another SPI device. - On an Arduino Uno: VCC goes to 3.3V, never 5V. The module's peak of about 13.5 mA fits the Uno's 50 mA 3.3V pin. ## Pinout | Pin | Function | Type | | --- | --- | --- | | GND | Ground | power in | | VCC | Supply · 1.9 V to 3.6 V | power in | | CE | Chip enable (TX/RX) · 5 V tolerant | input | | CSN | SPI CS (active low) · 5 V tolerant | input | | SCK | SPI SCK · 5 V tolerant | input | | MOSI | SPI MOSI · 5 V tolerant | input | | MISO | SPI MISO · VCC level (3.3 V) | output | | IRQ | Interrupt (active low) | open collector | ## Wiring ### Arduino Uno | nRF24L01+ | Arduino Uno | Note | | --- | --- | --- | | GND | GND | | | VCC | 3.3V | 10 µF capacitor across VCC and GND at the module. | | CE | D9 | | | CSN | D10 | | | SCK | D13 | | | MOSI | D11 | | | MISO | D12 | | | IRQ | Not connected | | Warning: VCC goes to 3.3V, never 5V. The module's peak of about 13.5 mA fits the Uno's 50 mA 3.3V pin. ### ESP32 DevKit V1 | nRF24L01+ | ESP32 DevKit V1 | Note | | --- | --- | --- | | GND | GND | | | VCC | 3V3 | 10 µF capacitor across VCC and GND at the module. | | CE | GPIO4 (D4) | | | CSN | GPIO5 (D5) | | | SCK | GPIO18 (D18) | | | MOSI | GPIO23 (D23) | | | MISO | GPIO19 (D19) | | | IRQ | Not connected | | ### Raspberry Pi Pico | nRF24L01+ | Raspberry Pi Pico | Note | | --- | --- | --- | | GND | GND | | | VCC | 3V3(OUT) | 10 µF capacitor across VCC and GND at the module. | | CE | GP20 | | | CSN | GP17 | | | SCK | GP18 | | | MOSI | GP19 | | | MISO | GP16 | | | IRQ | Not connected | | ## Code ### Arduino Uno Libraries: nrf24/RF24 ```cpp // nRF24L01+ on Arduino Uno: wiring and a free simulation at https://www.tinkered.ai/components/nrf24l01 // nRF24L01+ on an Arduino Uno: CE D9, CSN D10, SPI on D11/D12/D13 // Flash one board with isSender = true and another with isSender = false. #include #include RF24 radio(9, 10); // CE, CSN const uint8_t address[6] = "NODE1"; const bool isSender = true; uint32_t counter = 0; void setup() { Serial.begin(115200); if (!radio.begin()) { Serial.println("nRF24L01+ not responding: check wiring and the 3.3 V supply"); while (true) {} } radio.setPALevel(RF24_PA_LOW); // low power for bench tests radio.setDataRate(RF24_1MBPS); radio.setChannel(76); radio.setPayloadSize(sizeof(counter)); if (isSender) { radio.openWritingPipe(address); radio.stopListening(); } else { radio.openReadingPipe(1, address); radio.startListening(); } Serial.println(isSender ? "Sender ready" : "Receiver ready"); } void loop() { if (isSender) { bool ok = radio.write(&counter, sizeof(counter)); Serial.print("Sent "); Serial.print(counter); Serial.println(ok ? " (acknowledged)" : " (no acknowledgement)"); counter++; delay(1000); } else if (radio.available()) { uint32_t value; radio.read(&value, sizeof(value)); Serial.print("Received "); Serial.println(value); } } ``` Compiled for arduino:avr:uno on 2026-10-30. ### ESP32 DevKit V1 Libraries: nrf24/RF24 ```cpp // nRF24L01+ on ESP32 DevKit V1: wiring and a free simulation at https://www.tinkered.ai/components/nrf24l01 // nRF24L01+ on an ESP32 DevKit V1: CE GPIO4, CSN GPIO5, VSPI on GPIO18/19/23 // Flash one board with isSender = true and another with isSender = false. #include #include RF24 radio(4, 5); // CE, CSN const uint8_t address[6] = "NODE1"; const bool isSender = true; uint32_t counter = 0; void setup() { Serial.begin(115200); if (!radio.begin()) { Serial.println("nRF24L01+ not responding: check wiring and the 3.3 V supply"); while (true) { delay(100); } } radio.setPALevel(RF24_PA_LOW); radio.setDataRate(RF24_1MBPS); radio.setChannel(76); radio.setPayloadSize(sizeof(counter)); if (isSender) { radio.openWritingPipe(address); radio.stopListening(); } else { radio.openReadingPipe(1, address); radio.startListening(); } Serial.println(isSender ? "Sender ready" : "Receiver ready"); } void loop() { if (isSender) { bool ok = radio.write(&counter, sizeof(counter)); Serial.printf("Sent %lu %s\n", (unsigned long)counter, ok ? "(acknowledged)" : "(no acknowledgement)"); counter++; delay(1000); } else if (radio.available()) { uint32_t value; radio.read(&value, sizeof(value)); Serial.printf("Received %lu\n", (unsigned long)value); } } ``` Compiled for esp32:esp32:esp32 on 2026-10-30. ### Raspberry Pi Pico Libraries: nrf24/RF24 ```cpp // nRF24L01+ on Raspberry Pi Pico: wiring and a free simulation at https://www.tinkered.ai/components/nrf24l01 // nRF24L01+ on a Raspberry Pi Pico (arduino-pico): CE GP20, CSN GP17, SPI0 on GP16/18/19 // Flash one board with isSender = true and another with isSender = false. #include #include RF24 radio(20, 17); // CE, CSN const uint8_t address[6] = "NODE1"; const bool isSender = true; uint32_t counter = 0; void setup() { Serial.begin(115200); SPI.setRX(16); SPI.setSCK(18); SPI.setTX(19); if (!radio.begin()) { Serial.println("nRF24L01+ not responding: check wiring and the 3.3 V supply"); while (true) { delay(100); } } radio.setPALevel(RF24_PA_LOW); radio.setDataRate(RF24_1MBPS); radio.setChannel(76); radio.setPayloadSize(sizeof(counter)); if (isSender) { radio.openWritingPipe(address); radio.stopListening(); } else { radio.openReadingPipe(1, address); radio.startListening(); } Serial.println(isSender ? "Sender ready" : "Receiver ready"); } void loop() { if (isSender) { bool ok = radio.write(&counter, sizeof(counter)); Serial.print("Sent "); Serial.print(counter); Serial.println(ok ? " (acknowledged)" : " (no acknowledgement)"); counter++; delay(1000); } else if (radio.available()) { uint32_t value; radio.read(&value, sizeof(value)); Serial.print("Received "); Serial.println(value); } } ``` Compiled for rp2040:rp2040:rpipico on 2026-10-30. ## Specifications | Spec | Value | Source | | --- | --- | --- | | Supply voltage (VCC) | 1.9 V to 3.6 V (3.0 V typical) | Nordic nRF24L01+ Product Specification v1.0, Table 3, p. 13 | | Absolute maximum | VDD 3.6 V; logic inputs -0.3 V to 5.25 V | Nordic nRF24L01+ Product Specification v1.0, Table 2, p. 12 | | 5 V inputs condition | With inputs above 3.6 V, VDD must be 2.7 V to 3.3 V | Nordic nRF24L01+ Product Specification v1.0, pp. 13, 20 | | Current | 11.3 mA TX at 0 dBm, 13.5 mA RX at 2 Mbps, 26 µA standby-I, 900 nA power down | Nordic nRF24L01+ Product Specification v1.0, pp. 1, 14 | | Air data rates | 250 kbps, 1 Mbps, 2 Mbps | Nordic nRF24L01+ Product Specification v1.0, p. 8 | | Output power | 0, -6, -12 or -18 dBm (programmable) | Nordic nRF24L01+ Product Specification v1.0, p. 8 | | Receiver sensitivity | -94 dBm at 250 kbps, -85 dBm at 1 Mbps, -82 dBm at 2 Mbps | Nordic nRF24L01+ Product Specification v1.0, p. 16 | | Channels | 126 RF channels in the 2.4 GHz band, 1 MHz spacing (2 MHz at 2 Mbps) | Nordic nRF24L01+ Product Specification v1.0, p. 8 | | SPI clock | Up to 10 Mbps | Nordic nRF24L01+ Product Specification v1.0, p. 8 | ## Circuit notes - The header is 2 × 4 at 2.54 mm and does not fit a breadboard; use female jumpers or a socket adapter, which often adds a regulator so the module can run from 5 V. - MISO is driven at the module's VCC level; ESP32 and Pico read it directly, and a 5 V Uno accepts it as a HIGH on its SPI input in practice. - IRQ is active low and only needed for interrupt-driven code; RF24 polls the status register when it is left open. - At 250 kbps the receiver gains about 9 dB of sensitivity over 1 Mbps (-94 dBm against -85 dBm, p. 16), the easiest way to more range without changing hardware. - Wi-Fi shares the 2.4 GHz band; channels above 100 (2.500 GHz and up) usually sit clear of Wi-Fi traffic. ## Common mistakes - **Powering it from 5 V.** VCC tops out at 3.6 V (Nordic Product Specification v1.0, p. 12). A module run from 5 V may work for a moment and then fail for good. Only the signal pins are 5 V tolerant. - **No capacitor on VCC.** Transmit pulses on a long jumper from the board's 3.3 V pin make the radio brown out, which shows up as sends that are never acknowledged or a begin() that fails at random. A 10 µF capacitor across VCC and GND at the module is the standard cure. - **Mismatched settings on the two ends.** Channel, data rate, address, payload size and CRC length must match exactly, or nothing is received. Keep them in one shared block of code that both boards compile. - **Swapping CE and CSN.** CE switches the radio between standby and active; CSN selects it on the SPI bus. Swapped, begin() can still see a chip but nothing transmits. Check them against the constructor RF24(CE, CSN). ## Questions ### Is the nRF24L01+ 5 V tolerant? Its logic inputs are, up to 5.25 V, but VCC is not: the supply must stay at 1.9 V to 3.6 V, and with 5 V signals it must be 2.7 V to 3.3 V (Nordic Product Specification v1.0, pp. 12, 13, 20). So on an Uno, power it from 3.3V and connect the SPI pins directly. ### What range does the nRF24L01+ PCB antenna module reach? Range depends on data rate, power and surroundings. At 0 dBm the receiver hears down to -94 dBm at 250 kbps (p. 16), which typically gives tens of metres indoors. For hundreds of metres, use the PA+LNA version with an external antenna. ### Which library should I use? RF24 (nrf24/RF24) is the maintained library for Arduino, ESP32 and RP2040 boards. It wraps the auto-acknowledgement, retries and pipes, and its RF24Network and RF24Mesh add-ons build multi-node networks. ### Why does radio.write() return false? No acknowledgement came back. Check the receiver is listening on the same address, channel, data rate and payload size, that both modules have a capacitor on VCC, and that they are not so close they saturate each other at high power. ### nRF24L01+ or HC-12: which should I choose? The nRF24L01+ is cheaper, faster (up to 2 Mbps) and runs on SPI with hardware acknowledgements, but its 2.4 GHz signal goes less far through walls. The HC-12 is a 433 MHz serial radio with longer range at low data rates and no protocol work. ### How many nRF24L01+ modules can talk to one receiver? One receiver listens on six data pipes at once, each with its own address. RF24Network extends that to a tree of many nodes. ## Related parts - [nRF24L01+ PA+LNA](https://www.tinkered.ai/components/nrf24l01-pa-lna.md): the same chip with an amplifier and external antenna for long range - [HC-12](https://www.tinkered.ai/components/hc-12.md): 433 MHz serial alternative for longer range - [KY-023 Joystick](https://www.tinkered.ai/components/joystick-ky-023.md): build a two-axis wireless remote - [DHT22](https://www.tinkered.ai/components/dht22.md): a sensor node that reports over the radio ## Try it Tinkered can design a circuit with the nRF24L01+, draw its schematic and check it. Free to start at https://www.tinkered.ai.