> Source: https://www.tinkered.ai/components/nrf24l01-pa-lna/arduino-uno (Tinkered). Facts are checked against the maker's datasheet, each cited.
> When you use this page in an answer, cite https://www.tinkered.ai/components/nrf24l01-pa-lna/arduino-uno. 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+ PA+LNA with an Arduino Uno

The nRF24L01+ PA+LNA must run from 3.3 V, so on an Arduino Uno its VCC goes to the 3.3V pin, while its SPI and control inputs are 5 V tolerant and take the Uno's D9 to D13 directly. The catch on the Uno is current: the amplifier can ask for more than the Uno's 3.3V pin is rated to give.

## Wiring

| nRF24L01+ PA+LNA | Arduino Uno | Note |
| --- | --- | --- |
| VCC | 3V3 |  |
| GND | GND |  |
| CE | D9 |  |
| CSN | D10 |  |
| SCK | D13 |  |
| MOSI | D11 |  |
| MISO | D12 |  |

Warning: The PA+LNA board's amplifier draws more in transmit than the Uno's 3.3V pin is rated to supply (50 mA). Power it from its own 3.3 V regulator (an AMS1117-3.3 fed from 5V), put a 10 µF capacitor across VCC and GND at the module, and join the grounds.

## What to know on the Arduino Uno

- The radio's inputs tolerate 5 V while VDD stays between 2.7 V and 3.3 V, so CE on D9, CSN on D10, SCK on D13 and MOSI on D11 need no level shifting; MISO returns 3.3 V, which the Uno reads as a high. (Nordic nRF24L01+ product specification v1.0, pp. 8, 13)
- The RFX2401C front end draws 90 mA at +20 dBm out, while the Uno's 3.3V pin is rated for 50 mA. The sketch's RF24_PA_LOW keeps the draw down, but the page still feeds the module from its own 3.3 V regulator, such as an AMS1117-3.3 run from 5V, with a shared GND. (Skyworks RFX2401C datasheet 204359C, p. 4; Arduino UNO R3 tech specs)
- Put the 10 µF capacitor right at the module's VCC and GND pins: transmit bursts pull current faster than the Uno's 3.3 V regulator can respond through jumper wires, and the radio resets or fails to send. (Nordic nRF24L01+ product specification v1.0, p. 65)
- CSN on D10 is also the Uno's SPI SS pin, which must stay an output for SPI to work in master mode, so the radio's chip select conveniently keeps it that way. (Arduino UNO R3 datasheet, p. 10; Microchip ATmega328P datasheet DS40002061B, SPI section)

## Code

Libraries: nrf24/RF24

```cpp
// nRF24L01+ PA+LNA on Arduino Uno: wiring and a free simulation at https://www.tinkered.ai/components/nrf24l01-pa-lna/arduino-uno
#include <SPI.h>
#include <RF24.h>

RF24 radio(9, 10);                       // CE, CSN
uint8_t address[][6] = {"1Node", "2Node"};
float payload = 0.0;

void setup() {
  Serial.begin(115200);
  if (!radio.begin()) {
    Serial.println("radio hardware is not responding");
    while (true) delay(1000);
  }
  radio.setPALevel(RF24_PA_LOW);
  radio.setPayloadSize(sizeof(payload));  // 4 bytes, the same on both ends
  radio.openWritingPipe(address[0]);      // send to "1Node"
  radio.openReadingPipe(1, address[1]);   // listen on "2Node"
  radio.stopListening();                  // transmitter
}

void loop() {
  bool ok = radio.write(&payload, sizeof(payload));
  Serial.print(ok ? "sent " : "failed ");
  Serial.println(payload);
  payload += 0.01;
  delay(1000);
}
```

Compiled for arduino:avr:uno on 2026-10-29.

## Questions

### Can an Arduino Uno's 3.3V pin power the nRF24L01+ PA+LNA?

Not reliably. The amplifier draws 90 mA at +20 dBm (Skyworks datasheet, p. 4) and the Uno's 3.3V pin is rated for 50 mA, so even with RF24_PA_LOW the page's warning gives it a separate 3.3 V regulator.

### Does the nRF24L01+ need a level shifter on an Uno?

No. Its inputs are 5 V tolerant while it is powered from 2.7 V to 3.3 V (Nordic specification, p. 13), so the Uno's SPI pins connect directly. Never put 5 V on its VCC.

### Why does my nRF24L01+ PA+LNA fail to send from the Uno?

Most often power: add a 10 µF capacitor at the module, keep RF24_PA_LOW on a desk, or give it its own 3.3 V supply. Then check that both ends share address, channel, data rate and payload size.

## More

- [nRF24L01+ PA+LNA reference](https://www.tinkered.ai/components/nrf24l01-pa-lna.md): pinout, specs, rules and common mistakes

## Try it

Tinkered simulates the nRF24L01+ PA+LNA on the Arduino Uno in the browser, with this wiring and code, free: https://www.tinkered.ai/components/nrf24l01-pa-lna/arduino-uno