nr24L01 always returns status + 0x00

Wireless & IoT
1

Hi ,

i’m trying nrf24L01+ in my own design : nrf24L01 + ADµC(ARM7)

my SPI driver is well (loopback tested) but every command i try to read any register only returns me 0x0E 0x00 …0x00.

all signals are well : MISO / MOSI /SCK / CS has been controlled with an oscilloscope

I see another topic where this problem was solved by modifying clock polarity. In my case, this only change 0x0E with 0x1C (1bit left shift)

any idea ?

mat

2

Here is some PIC18 code of mine for testing SPI that might help:

/*
** 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

3

excellent !

i forgot to configure SCK to idle low as described in your code.

thanks for your help