No response from nRF24L01+

Wireless & IoT
1

Hi. I’m trying to make two microcontrollers communicate wirelessly using two nRF24L01+'s. For what it’s worth, I’m using Atmega328 and the breakout board for the nRF24L01+. For the SPI connection, I’m using http://www.arduino.cc/playground/Code/Spi. Anyway, I set it up with just the SPI connection (and power/ground, of course) to the chip and, as a test, tried to read the STATUS register by sending binary 11111111 through SPI. The nRF returned 0x0, but should have returned 0x15 based on the default values for STATUS from the datasheet. To ensure that I’d connected the SPI properly, I connected the MOSI to MISO, and I was indeed receiving back exactly what I was sending. Any ideas? I’ve included the code that I’m using below, although it’s so simple that it hardly seems worth it. Thanks.

#include <Spi.h>

void setup(){
  Serial.begin(9600);
}

void loop(){
  Serial.print(Spi.transfer(B11111111),HEX);
  Serial.print("\n\r");
}
2

Here is my SPI test code for the nRF24L01. I used a PIC18F4520, but it should be easy to port it to the AVR. I used the C18 SPI peripheral library.

/*
** test.c
** SPI test program for PIC18F4520 and nRF24L01 or nRF24L01+
** Checks SPI comms between PIC and wireless chip
** 
** RA0	LED (output)
** RA1	PB (input)
*/

#include <p18f4520.h>
#include <spi.h>

//function prototypes
unsigned char spi_Send_Read(unsigned char);

// Defines
#define SPI_SCK		LATCbits.LATC3		// Clock pin, PORTC pin 3 
#define SPI_SO		LATCbits.LATC5		// Serial output pin, PORTC pin 5 
#define SPI_SI		PORTCbits.RC4		// Serial input pin, PORTC pin 4 
#define SPI_CSN		LATCbits.LATC2		// CSN output pin, PORTC pin 2
#define SPI_CE		LATCbits.LATC1		// CE output pin, PORTC pin 1
#define SPI_IRQ		PORTBbits.RB0		// IRQ input pin, PORTB pin 0
#define SPI_SCALE	4              		// postscaling of signal 
#define LED			LATAbits.LATA0
#define PB			PORTAbits.RA1


// Macros
#define nop() _asm nop _endasm

void main(void)
{
	unsigned char status = 0;
	unsigned char data[5];
	int i;

	// run internal oscillator at 8 MHz
	OSCCON = OSCCON | 0x70;
	while (OSCCONbits.IOFS == 0)
		;

	OpenSPI(SPI_FOSC_16, MODE_00, SMPMID); //open SPI1
	PORTA = 0x00;
	ADCON1 = 0x0F;		// set up PORTA to be digital I/Os
	TRISA = 0x02;		// PORTA<7.2,0> outputs PORTA<1> input
	TRISCbits.TRISC3 = 0;	// SDO output
	TRISCbits.TRISC5 = 0;   // SCK output
	TRISCbits.TRISC2 = 0;	// CSN output
	TRISCbits.TRISC1 = 0;	// CE output
	SPI_CSN = 1;		// CSN high
	SPI_SCK = 0;		// SCK low
	SPI_CE	= 0;		// CE low
	nop();

	//write TX_ADDRESS register
	SPI_CSN = 0;			//CSN low
	spi_Send_Read(0x30);
	spi_Send_Read(0x11);
	spi_Send_Read(0x22);
	spi_Send_Read(0x33);
	spi_Send_Read(0x44);
	spi_Send_Read(0x55);
	SPI_CSN = 1;			//CSN high


	//read TX_ADDRESS register
	//Check that values are correct using the MPLAB debugger
	SPI_CSN = 0;			//CSN low
	status = spi_Send_Read(0x10);
	data[0] = spi_Send_Read(0x00);	// 0x11
	data[1] = spi_Send_Read(0x00);	// 0x22
	data[2] = spi_Send_Read(0x00);	// 0x33
	data[3] = spi_Send_Read(0x00);	// 0x44
	data[4] = spi_Send_Read(0x00);	// 0x55
	SPI_CSN = 1;			//CSN high

	// test PB and LED
	while(1)
	{
		if (!PB)
			LED = 1;
		else
			LED = 0;
	}
}


unsigned char spi_Send_Read(unsigned char byte)
{
	SSPBUF = byte;	
	while(!DataRdySPI())
		;	
	return SSPBUF;
}

Leon