nRF24L01 transmission speeds.

Wireless & IoT
1

Hello

I am working with the nRF24L01 and my goal is to send out 10 packets, with unique addresses, as quickly as possible.

The nRF24L01 is connected to a PIC (clocked at 32MHz) via hardware SPI (clocked at DIV4 (8MHz)).

ACK is disabled.

The following transmit sequence takes about 3ms.

void Transmit_Data() {

   for (0, forvar = 1; forvar < 11; forvar++) {

      CSN = 0;

      Spi_Write(0x30); //Command : 'W_Register' : Write to register 0x0A (RX_ADDR_P0)
      Spi_Write(0xCC); //set address E7E7E7E7xx
      Spi_Write(0xBB);
      Spi_Write(0xEE);
      Spi_Write(0xDD);
      Spi_Write(forvar);

      CSN = 1;

      CSN = 0;

      Spi_Write(0x27); //Command : 'W_Register' : Write to register 0x07 (STATUS)
      Spi_Write(0b01110000); //Clear previous interrupts

      CSN = 1;

      CSN = 0;

      Spi_Write(0b10100000); //Command : 'W_TX_PAYLOAD' : Write TX Payload

      for (0, forvar2 = 1; forvar2 < 11; forvar2++) { //Clock out data to TX Payload

         for (0, forvar3 = 1; forvar3 < 4; forvar3++) {

            Spi_Write(RGB_Values[forvar3][forvar2][forvar]); //[0,R,G,B][Channel 1-10][Solar System 1-10]

         }
      }

      CSN = 1;


      CE = 1;   //Start transmission

      while (IRQ == 1) {} //Hold until packet is sent / TX_DS interrupt is set

   }

   CE = 0;

} //end Transmit_Data()

Is there a way the packets can be transmitted quicker than 3ms?

Thanks.

BTW: Here is the config routine…

void Configure_Transmitter() {

    CE = 0;  //When in TX mode : sets "No ongoing packet transmission"

    CSN = 0;

    Spi_Write(0x20); //Command : 'W_Register' : Write to register 0x00 (CONFIG)
    Spi_Write(0b01011010); //PTX, CRC enabled, mask a couple of ints (TX_DS and MAX_RT)

    CSN = 1;

    CSN = 0;

    Spi_Write(0x21);  //Command : 'W_Register' : Write to register 0x01 (EN_AA)
    Spi_Write(0x00);  //disable auto-ack

    CSN = 1;

    CSN = 0;

    Spi_Write(0x23); //Command : 'W_Register' : Write to register 0x03 (SETUP_AW)
    Spi_Write(0x03); //Address width = 5

    CSN = 1;

    CSN = 0;

    Spi_Write(0x24); //Command : 'W_Register' : Write to register 0x04 (SETUP_RETR)
    Spi_Write(0x00); //Auto retransmit off

    CSN = 1;

    CSN = 0;

    Spi_Write(0x25);  //Command : 'W_Register' : Write to register 0x05 (RF_CH)
    Spi_Write(0x02);  //Set Channel to '2'

    CSN = 1;

    CSN = 0;

    Spi_Write(0x26);  //Command : 'W_Register' : Write to register 0x06 (RF_SETUP)
    Spi_Write(0x07);  //Data rate = 1Mbps , RF output = 0dBm

    CSN = 1;

    CSN = 0;

    Spi_Write(0x2A);  //Command : 'W_Register' : Write to register 0x0A (RX_ADDR_P0)
    Spi_Write(0xE7);  //Set address to E7E7E7E7E7
    Spi_Write(0xE7);
    Spi_Write(0xE7);
    Spi_Write(0xE7);
    Spi_Write(0xE7);

    CSN = 1;

    CSN = 0;

    Spi_Write(0x30); //Command : 'W_Register' : Write to register 0x10 (TX_ADDR)
    Spi_Write(0xE7); //set address E7E7E7E7E7
    Spi_Write(0xE7);
    Spi_Write(0xE7);
    Spi_Write(0xE7);
    Spi_Write(0xE7);

    CSN = 1;

    //dont raise CE... CE = 1 = ongoing packet transmission

} //end Configure_Transmitter()
2

Yes it is!

Take advantage of the devices three packet buffer. Put it in active mode, with CE low. Upload three packets, and set CE high. On the data sent interrupt you upload the next packet. This way, the nRF24L01 is constantly sending data.

To shave off a few microseconds, you could try to write only to register 0x0F when changing the RX address.

3

I changed a few things around… basically the address is changed and the next packet is uploaded while waiting for the TX_DS int flag to trigger.

It cuts the time down about one third… but all and all it still is a bit slow…

void Transmit_Data() {

   CSN = 0;

   Spi_Write(0x30); //Command : 'W_Register' : Write to register 0x10 (TX_ADDR)
   Spi_Write(0xCC); //set address E7E7E7E7xx
   Spi_Write(0xBB);
   Spi_Write(0xEE);
   Spi_Write(0xDD);
   Spi_Write(1);

   CSN = 1;

   CSN = 0;

   Spi_Write(0b10100000); //Command : 'W_TX_PAYLOAD' : Write TX Payload

   for (0, forvar2 = 1; forvar2 < 11; forvar2++) { //Clock out data to TX Payload

      for (0, forvar3 = 1; forvar3 < 4; forvar3++) {

         Spi_Write(RGB_Values[forvar3][forvar2][1]); //[0,R,G,B][Channel 1-10][Solar System 1-10]

      }
   }

   CSN = 1;

   for (0, forvar = 2; forvar < 11; forvar++) { //transmit one cluster at a time

      CSN = 0;

      Spi_Write(0x27); //Command : 'W_Register' : Write to register 0x07 (STATUS)
      Spi_Write(0b01110000); //Clear previous interrupts

      CSN = 1;


      CE = 1;   //Start transmission


      //change address and load next packet while waiting for TX to finish

      CSN = 0;

      Spi_Write(0b10100000); //Command : 'W_TX_PAYLOAD' : Write TX Payload

      for (0, forvar2 = 1; forvar2 < 11; forvar2++) { //Clock out data to TX Payload

         for (0, forvar3 = 1; forvar3 < 4; forvar3++) {

            Spi_Write(RGB_Values[forvar3][forvar2][forvar]); //[0,R,G,B][Channel 1-10][Solar System 1-10]

         }
      }

      CSN = 1;

      CSN = 0;

      Spi_Write(0x30); //Command : 'W_Register' : Write to register 0x10 (TX_ADDR):
      Spi_Write(0xCC); //set address E7E7E7E7xx
      Spi_Write(0xBB);
      Spi_Write(0xEE);
      Spi_Write(0xDD);
      Spi_Write(forvar);

      CSN = 1;

      while (IRQ == 1) {} //hold here until finished transmitting

   }

   CE = 0; //disable transmission

} //end Transmit_Data()