Hi Guys,
I´m totally new here and this is my first post.
I´m trying to create a digital stop watch with a IR-Light Barrier and wireless communication.
I´m using two micro´s and two "e18-d50nk" for communication two "NRF24L01".
The distance between the two IR-Sensors is ca. 30m.
I wired up every thing correct and the code works.
When the first Sensors Starts the Stopwatch runs and shows me on the LCD. When the second sensor is pulled down a char[] "S" will be send and the reciever stops with the stopwatch.
MY PROBLEM NOW:
When one arduino is powered with the USB, so when it´s connected with the Serial the Reciever can communiced with transmitter.
But when I power the two arduinos with a external power supply unit, the stop watch begins to count when i hit the first sensor, but it doesent recieve any data from the transmitter.
I installed a Piezo to hear it, when the transmitter is sendig data, or the reciever is getting data, the transmitter is sendig data, with external power, but the reciever doesn´t take it.
I can´t find the problem, why does the arduino nothing recieve, when it´s powered by a external power supply.
I also tried to start first the transmitter, and then the reciever and reversed, but it doesn´t help anything.
HAS ANYONE EXPERIENCE WITH THIS?
THANK`S A LOT 
Here the Code:
TRANSMITTER:
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
//-----------------------
RF24 radio(7, 8);
const byte rxAddr[6] = "00001";
//FOR BEEPER
//-------------------
int Speaker = 2;
//-------------------
//FOR SENSOR
//-------------------
int Input_Sensor = 12;
char test[] = "S";
//-------------------
//SETUP
void setup()
{
//Serial.begin(9600);
radio.begin();
radio.setRetries(15, 15);
radio.openWritingPipe(rxAddr);
radio.stopListening();
pinMode(Input_Sensor, INPUT);
pinMode(Speaker, OUTPUT);
}
//DEFINE FUNCTIONS
void BEEP(int frequency);
//LOOP
void loop()
{
if(digitalRead(Input_Sensor) == HIGH)
{
radio.write(&test, sizeof(test));
BEEP(200);
}
}
//PEEP FUNCTION FOR SPEAKER
void BEEP(int frequency)
{
// generate a 1KHz tone for 1/2 second
for (int i = 0; i < 500; i++)
{
digitalWrite(Speaker, HIGH);
delayMicroseconds(frequency);
digitalWrite(Speaker, LOW);
delayMicroseconds(frequency);
}
}
RECIEVER:
//Libraries
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#include <LiquidCrystal.h>
//----------------------------
RF24 radio(7, 8);
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
const byte rxAddr[6] = "00001";
//FOR STOPWATCH
//-------------------
double i = 0;
double a = millis();
double c ;
int Input_Sensor = 9;
//-------------------
//FOR BEEPER
//-------------------
int Speaker = 6;
//-------------------
//DEFINE FUNCTIONS
void BEEP(int frequency);
void setup()
{
//Serial.begin(9600);
radio.begin();
radio.openReadingPipe(0, rxAddr);
radio.startListening();
pinMode(Input_Sensor,INPUT);
pinMode(Speaker, OUTPUT);
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// Print a message to the LCD.
lcd.print(" -STOP WATCH V1-");
delay(1000);
}
void loop()
{
a = millis();
if(digitalRead(Input_Sensor) == LOW)
{
char text[32] = {0};
do
{
c = millis();
i = (c - a) / 1000;
lcd.setCursor(0, 1);
// print the number of seconds since reset:
Serial.println(i);
lcd.print(i);
lcd.print(" Sekunden");
//if (radio.available())
{
radio.read(&text, sizeof(text));
Serial.println(text);
}
}while(text[0] != 'S');
}
}
//BEEP FUNCTION FOR SPEAKER
void BEEP(int frequency)
{
// generate a 1KHz tone for 1/2 second
for (int i = 0; i < 500; i++)
{
digitalWrite(Speaker, HIGH);
delayMicroseconds(frequency);
digitalWrite(Speaker, LOW);
delayMicroseconds(frequency);
}
}
