Need help with error "void value not ignored as it ought to be"

Projects Programming
1

Hi all.

My digital weather station is now up and running (thanks again to all those forum members who helped me with the problems i encountered while building it)

I now wish to move on to the next phase of the weather station project, which is to make it send it's data by WI - FI (I currently of course have to take the data by going outside to collect the data, would be nice to stay in the warm indoors and collect the data.)

I have started by using Arduino UNO + Servo + NRF24L01 modules, i have used sketches from an Instructables web site, the transmitter sketch uploaded first time, the problem i have is with the receiver sketch, i get this error message "void value not ignored as it ought to be" having scoured the internet for days now, and getting nowhere, i thought i need help to point me in the right direction to correct the error.

Here is the sketch,

#include <Servo.h>
#include <SPI.h>
#include "RF24.h"

Servo myservo; //SCK -> 13//MISO -> 12//MOSI -> 11//CSN -> 7//CE -> 8
RF24 radio(8,7);

const uint64_t pipe = 0xE8E8F0F0E1LL;
int msg[1];

void setup(){

myservo.attach(9);
radio.begin();
radio.openReadingPipe(1,pipe);
radio.startListening();

}

void loop(){

if (radio.available())

{

bool done = false;

while (!done)

{

done = radio.read(msg, 1);

myservo.write (msg[0]);

}

the line "done = radio.read(msg,1);" is highlighted in the IDE, so i reckon it's this line which is wrong, i also noticed that in this line it has msg.1 with parenthesis, while the next line uses both parentheses and squared brackets ???

2

so i reckon it's this line which is wrong

Well, duh.

There are several versions of the RF24. Some versions have read() return a boolean. Some do not. Your code must match the version you are using. Your code does not.

3

It would be helpful to see the transmitter code too.

What is the servo supposed to do? Guessing, I'm wondering if it's got a pointer on it to indicate temperature.

4

Hi wildbill.

The servo is just there for me to practice with using Tx & Rx, it's a bit difficult to get the weather station back into my house as it's so big and heavy.

Here is the Transmitter sketch -

#include <SPI.h>
#include "RF24.h"

int msg[1]; //SCK -> 13//MISO -> 12//MOSI -> 11//CSN -> 7//CE -> 8
RF24 radio(8,7);

const uint64_t pipe = 0xE8E8F0F0E1LL;
int potpin = 0;
int val;

void setup(void){

radio.begin();
radio.openWritingPipe(pipe);

}

void loop(void){

val = analogRead(potpin);
val = map(val, 0, 1023, 0, 179);
msg[0] = val;
radio.write(msg, 1);

}
5

To PaulS' point, it would be useful to know which RF24 library you are using.

Substituting this for your loop function will probably get your system compiling at least:

void loop()
{
if (radio.available())
  {
   radio.read(msg, 1);
   myservo.write (msg[0]);
   }
}

Once you establish that you have radio communications though, you're going to need to think about a protocol so that the two ends can agree what's being sent. What measurements do you plan to send to the hardware indoors?

6

Hi.

Here is the Library i am using.

RF24-master.zip (362 KB)

7 
  /**
   * Read the available payload
   *
   * The size of data read is the fixed payload size, see getPayloadSize()
   *
   * @note I specifically chose 'void*' as a data type to make it easier
   * for beginners to use.  No casting needed.
   *
   * @note No longer boolean. Use available to determine if packets are
   * available. Interrupt flags are now cleared during reads instead of
   * when calling available().
   *
   * @param buf Pointer to a buffer where the data should be written
   * @param len Maximum number of bytes to read into the buffer
   *
   * @code
   * if(radio.available()){
   *   radio.read(&data,sizeof(data));
   * }
   * @endcode
   * @return No return value. Use available().
   */
  void read( void* buf, uint8_t len );

The read method in that library returns a void, not a bool.

            while(radio.available() ){                      // If an ack with payload was received
                radio.read( &gotByte, 1 );                  // Read it, and display the response time

The examples do not try to use the return value.

Why are you?