Connection between ATTiny85 and RaspberryPi3 with nRF24L01+ I'm hoping someone can help me since I've been struggling with this all weekend. I've got 2 nRF24L01+ breakout cards and I'm trying to send data from a ATTiny85 to a Raspberry Pi 3.

My setup is (the attiny85 breadboard has a 3.3V power supply):





And the code I'm testing is for the ATTiny85:

#define CE_PIN 3
#define CSN_PIN 4

#include "RF24.h"

RF24 radio(CE_PIN, CSN_PIN);

const byte addr[6] = "00001";
int count = 0;

void setup() {
  radio.begin();
  radio.openWritingPipe(addr);
  radio.setPALevel(RF24_PA_MIN);
  radio.stopListening();
}

void loop(void){
  radio.write( &amp;count, sizeof(count) );
  count++;
  delay(1000);
}


And for the Raspberry Pi 3:

#include &lt;cstdlib&gt;
#include &lt;iostream&gt;
#include &lt;sstream&gt;
#include &lt;string&gt;
#include &lt;unistd.h&gt;
#include &lt;RF24/RF24.h&gt;

using namespace std;

// Setup for GPIO 22 CE and CE0 CSN with SPI Speed @ 8Mhz
RF24 radio(RPI_V2_GPIO_P1_22, RPI_V2_GPIO_P1_24, BCM2835_SPI_SPEED_8MHZ);

// Radio pipe addresses for the 2 nodes to communicate.
const uint8_t addr[6] = "00001";

int main(int argc, char** argv){
  radio.begin();
  radio.setPALevel(RF24_PA_MIN);
  radio.openReadingPipe(1, addr);
  radio.startListening();

  // Dump the configuration of the rf unit for debugging
  radio.printDetails();

  int count = 0;

  while (1)
  {
    while ( radio.available() )
    {
      radio.read( &amp;count, sizeof(count) );
      printf("Count: %d\n", count);
    }
    sleep(1);
  }

  return 0;
}
As Mikael Patel pointed out, my MOSI and MISO pins were switched.

On the pinout for the ATtiny85, the MOSI and MISO pins are for when the chip is a slave (i.e. programming). DO and DI and used for output as SPI master.