2.4G Wireless nRF24L01p

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The nRF24L01+(nRF24L01p) is a single chip 2.4GHz transceiver with an embedded baseband protocol engine (Enhanced ShockBurst™), suitable for ultra low power wireless applications. The nRF24L01+ is designed for operation in the world wide ISM frequency band at 2.400 - 2.4835GHz.
To design a radio system with the nRF24L01+, you simply need an MCU (microcontroller) and a few exter-nal passive components. The high air data rate combined with two power saving modes make the nRF24L01+ very suitable for ultra low power designs. nRF24L01+ is drop-in compatible with nRF24L01 and on-air compatible with nRF2401A, nRF2402, nRF24E1 and nRF24E2. Intermodulation and wideband blocking values in nRF24L01+ are much improved in comparison to the nRF24L01 and the addition of internal filtering to nRF24L01+ has improved the margins for meeting RF regulatory standards.
Model: RFM04
N24l01 figure01.jpg


  • Worldwide 2.4GHz ISM band operation,Free license to use.
  • 126 RF channels.
  • High air data rate: 250kbps, 1 and 2Mbps.
  • Transmitter: 11.3mA at 0dBm output power.
  • Receiver: Fast AGC for improved dynamic range.
  • Receiver: Integrated channel filters.
  • Enhanced ShockBurst™:1 to 32 bytes dynamic payload length,6 data pipe MultiCeiver™ for 1:6 star networks.
  • Host Interface:4-pin hardware SPI,3 separate 32 bytes TX and RX FIFOs.
  • Low Power Management:1.9 to 3.6V supply range.
  • GFSK modulation.
  • Auto packet transaction handling.
  • Easy for designed.
  • Small size:15mm*29mm.

Application Ideas

  • Wireless PC Peripherals
  • Mouse, keyboards and remotes
  • 3-in-1 desktop bundles
  • Advanced Media center remote controls
  • VoIP headsets
  • Game controllers
  • Sports watches and sensors
  • RF remote controls for consumer electronics
  • Home and commercial automation
  • Ultra low power sensor networks
  • Active RFID
  • Asset tracking systems
  • Toys
  • 2 Channel Relay Sheild

SHD RL01 3.jpg


  • VCC is range of 1.9V~3.6V, do not exceed this range, otherwise it by destroyed the module.
  • Except of VCC and GND,the other pins can be direct connected to 5V Microprocessor's IO, needless level converter. Of course 3V Microprocessor's IO more applied.
  • If the Microprocessor isn't hardware SPI interface,could be simulated with ordinary IO.
  • If connected to 51 series MCU's P0, there is a 10K Pull-up resistor need,others Port needless.
  • If Microprocessor IO more than 10mA,need connect 2K resistive divider. It could direct connected to AVR Series.


Board Schematic

N24l01 figure02.jpg

Schematic Diagram

N24l01 figure03.jpg


Specification Value
PCB Size 15mm*29mm*0.8mm
Power supply 1.9V~3.6V
Working current 13.5mA at 2Mbps / 11.3mA at 0dBm output power
IO counts 8
Sensitivity -85dBm at 1Mbps
Emission distance 70~100 meter at 256kbps
Data rate 256kbps / 1Mbps / 2Mbps
Commuinitcation mode Enhanced ShockBurst TM / ShockBurst TM
Working mode Power Down Mode / Standby Mode / RX Mode / TX Mode
Temperatures Operating:-40°C ~ 85°C / Storage:-40°C ~ 125°C

Pin definition and Rating

3 CE 4 CSN

Mechanic Dimensions


  • Enhanced ShockBurst™

The Enhanced ShockBurst™ features enable significant improvements of power efficiency for bi-directional and uni-directional systems, without adding complexity on the host controller side. In Enhanced ShockBurst™ it is possible to configure parameters such as the maximum number of retrans- mits and the delay from one transmission to the next retransmission. All automatic handling is done without the involvement of the MCU. it could be for wireless mouse wireless keyboard.

  • ShockBurst™

ShockBurst™ makes it possible to use the high data rate offered by nRF24L01 without the need of a costly, high-speed microcontroller (MCU) for data processing/clock recovery.In ShockBurst™ TX, nRF24L01 automatically generates preamble and CRC, it compatable with nRF2401A, nRF24E1, nRF2402 and nRF24E2 communication.

If you want use 6 data pipe MultiCeiver™ for 1:6 star networks, selection Enhanced ShockBurst™ N24l01 figure04.jpg
nRF24L01 in a star network configuration.
An nRF24L01 configured as primary RX (PRX) will be able to receive data trough 6 different data pipes, see Figure 4. A data pipe will have a unique address but share the same frequency channel. This means that up to 6 different nRF24L01 configured as primary TX (PTX) can communicate with one nRF24L01 configured as PRX, and the nRF24L01 configured as PRX will be able to distinguish between them. Data pipe 0 has a unique 40 bit configurable address. Each of data pipe 1-5 has an 8 bit unique address and shares the 32 most significant address bits. All data pipes can perform full Enhanced ShockBurst™ functionality. nRF24L01 will use the data pipe address when acknowledging a received packet. This means that nRF24L01 will transmit ACK with the same address as it receives payload at. In the PTX device data pipe 0 is used to received the acknowledge, and therefore the receive address for data pipe 0 has to be equal to the transmit address to be able to receive the acknowledge. See Figure 5 for addressing example.

N24l01 figure05.jpg
Example on how the acknowledgement addressing is done.
An nRF24L01 configured as PTX with Enhanced ShockBurst™ enabled, will use the ShockBurst™ feature to send a packet whenever the microcontroller wants to. After the packet has been transmitted, nRF24L01 will switch on its receiver and expect an acknowledgement to arrive from the terminating part. If this acknowledgement fails to arrive, nRF24L01 will retransmit the same packet until it receives an acknowledgement or the number of retries exceeds the number of allowed retries given in the SETUP_RETR_ARC register. If the number of retries exceeds the number of allowed retries, this will show in the STATUS register bit MAX_RT and gives an interrupt. Whenever an acknowledgement is received by an nRF24L01 it will consider the last transmitted packet as delivered. It will then be cleared from the TX FIFO, and the TX_DS IRQ source will be set high. With Enhanced ShockBurst™ nRF24L01 offers the following benefits:

  • Highly reduced current consumption due to short time on air and sharp timing when operating with acknowledgement traffic
  • Lower system cost. Since the nRF24L01 handles all the high-speed link layer operations, like re-transmission of lost packet and generating acknowledgement to received packets, it is no need for hardware SPI on the systemmicrocontroller to interface the nRF24L01. The interface can be done by using general purpose IO pins on a low cost microcontroller where the SPI is emulated in firmware. With the nRF24L01 this will be sufficient speed even when running a bi-directional link.
  • Greatly reduced risk of “on-air” collisions due to short time on air
  • Easier firmware development since the link layer is integrated on chip

The actual communication process oscilloscope diagram

For nRF24L01 programming, mainly through the command (WRITE_REG, READ_REG, etc). Control line CE, CSN and the interrupt signal IRQ completed. Be Transmitte node, enable ACK and IRQ, after communicate successfull(received ACK from Accept node)IRQ to Low. Be Accpet node, disable ACK and IRQ,after communicate successfull(Based on Enhanced ShockBurst agreement that the successful receipt of a valid data width data) IRQ to Low. For more detail, we captured oscilloscope schematic:

Transmitting node CE and IRQ

The Yellow sigal is CE and Green sigal is IRQ. After setting module to Transmitting node. Then send data by SPI_Write_Buf(WRITE_REG + RX_ADDR_P0, TX_ADDRESS, TX_ADR_WIDTH) to FIFO. CE keep 10us,the data be seed through wireless. If enable IQR(TX_DS,RX_DS,MAX_RT), when the Transmitting node receive the ACK from Accpeting Node or reach MAX transmitte count. IRQ to Low and the same time the CONFIG flag(TX_DS,RX_DS,MAX_RT) to 1, clear the flag SPI_RW_Reg(WRITE_REG+STATUS,status); // clear RX_DR or TX_DS or MAX_RT interrupt flag and the IQR will to High level. As the figure show, after CE set High Level 10ms, the IQR to Low level. The reason is reach to Max transimitte count(MAX_RT=1). So there are not Accpeting Node or they are different address.

SCK and IRQ(Transmitting successfull)

The Green sigal is SCK, the Purple signal is CE, and the Yellow sigal is IRQ.The first part SCK is paired, when frist IRQ reach about 1ms. It is successfull paired and communication.

SCK and IRQ(Transmitting failed)

The Green sigal is SCK and the Yellow sigal is IRQ.The first part SCK is paired, when frist IRQ reach about 10ms. It is failed paired and communication.


The Purple signal is CE, the Green sigal is Accpeting node's IRQ and the Yellow sigal is Transmitting node's IRQ. The figure means:
After paired, CE is High level, and FIFO data will be send, then Accpeting node received the data, IRQ to Low level(Purple and green signal from the time interval between signals can determine the success of communication),then Accept node auto send ACK(enable ACK),then Transmitting node received ACK and set IQR Low level.Different communication environment may cause the Transmitting node and Accpeting node phase different.This is mainly due to the different communication environment receiver sends ACK signal to be re-issued several times in order to be received by the sender.


Includes important code snippet. Demo code like :
The Demo pins to Arduino as below:

GND – GND, VCC – 3.3V, CS – D8, CSN – D9, SCK – D10, MOSI – D11, MISO – D12, IRQ – D13

Download the code below into the TX Arduino (transmit) — This code will drive the nRF24L01 module to send out data form 0×00 to 0xFF .

Note: between the write TX_FIFO and clear RX_DR or TX_DS or MAX_RT interrupt flag, would better not serial print anything, which maybe case ACK failed.

<syntaxhighlight lang="php">

void setup() {

  SPI_DIR = ( CE + SCK + CSN + MOSI);
  SPI_DIR &=~ ( IRQ + MISO);
  //  attachInterrupt(1, _ISR, LOW);// interrupt enable
  init_io();                        // Initialize IO port
  unsigned char status=SPI_Read(STATUS);
  Serial.print("status = ");
  Serial.println(status,HEX);      // read the mode’s status register, the default value should be ‘E’
  Serial.println("*******************TX_Mode Start****************************");
  TX_Mode();                       // set TX mode

} void loop() {

  int k = 0;
    for(int i=0; i<32; i++)
        tx_buf[i] = k++;
    unsigned char status = SPI_Read(STATUS);                // read register STATUS's value
    if(status&TX_DS)                                        // if receive data ready (TX_DS) interrupt
      SPI_Write_Buf(WR_TX_PLOAD,tx_buf,TX_PLOAD_WIDTH);     // write playload to TX_FIFO
    if(status&MAX_RT)                                       // this is retransmit than  SETUP_RETR
      SPI_Write_Buf(WR_TX_PLOAD,tx_buf,TX_PLOAD_WIDTH);     // disable standy-mode
    SPI_RW_Reg(WRITE_REG+STATUS,status);                    // clear RX_DR or TX_DS or MAX_RT interrupt flag



Download the code below into the RX Arduino (receive) – This code will drive the nFR24L01 module to receive the data that transmit form the TX module and print it to serial port.

Note: clear RX_FIFO must bellow Read_FIFO

<syntaxhighlight lang="php">

void setup() {

  SPI_DIR = ( CE + SCK + CSN + MOSI);
  SPI_DIR &=~ ( IRQ + MISO);
  //  attachInterrupt(1, _ISR, LOW); // interrupt enable
  init_io();                        // Initialize IO port
  unsigned char status=SPI_Read(STATUS);
  Serial.print("status = ");
  Serial.println(status,HEX);      // read the mode’s status register, the default value should be ‘E’
  Serial.println("*****************RX_Mode start******************************R");
  RX_Mode();                        // set RX mode

} void loop() {

    unsigned char status = SPI_Read(STATUS);                // read register STATUS's value
    if(status&RX_DR)                                        // if receive data ready (TX_DS) interrupt
      SPI_Read_Buf(RD_RX_PLOAD, rx_buf, TX_PLOAD_WIDTH);    // read playload to rx_buf
      SPI_RW_Reg(FLUSH_RX,0);                               // clear RX_FIFO
      for(int i=0; i<32; i++)
          Serial.print(" ");
          Serial.print(rx_buf[i],HEX);                      // print rx_buf
      Serial.println(" ");
    SPI_RW_Reg(WRITE_REG+STATUS,status);                    // clear RX_DR/TX_DS/MAX_RT interrupt flag




The projects and application examples. These file are a sample code for your reference.

Bill of Materials (BOM) /parts list

All the components used to produce the product.


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Version Tracker

Revision Descriptions Release
v1.1 Initial public release date

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   *nRF24L01_sch.pdf                                   Schematic of the nRL24L01 module
   *nRF24L01_Specification_v2_0.pdf                    Datasheet of the nRL2401 chip
   *NRF24L01.JPG                                       Pin map of the nRF24L01 module
   *Demo_80S52.rar                                     Demo code for nRF24L01 module on 80S52
   *acceptavrnrf24l01.rar                              Accept date demo for nRF24L01 module on AVR
   *sendavrnrf24l01.rar                                Send data demo for nRF24L01 module on AVR

How to buy

Click here to buy: http://www.elecfreaks.com/store/24g-wireless-nrf24l01p-p-118.html

See Also

Other related products and resources.


This documentation is licensed under the Creative Commons Attribution-ShareAlike License 3.0 Source code and libraries are

licensed under GPL/LGPL, see source code files for details.

External Links

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