[solved] Problem with 433mhz radiohead lib sending integer

Projects Programming
1

Hello,
i'm having an issue using the library to send a simple integer, using radiohead 1.101 library
i've googled and found similar threads(Arduino 433 mhz rf Sending numbers instead of strings - Programming Questions - Arduino Forum) but i can't get it to work at all even using the examples on the source.

sending board is a Leonard, receiver a pro mini.
I checked basic functionality using the send/receive examples as-is and it works ok

Checking the radiohead.h source i see an example to send a 16 bit int, but i can't get it to work, receiver gets nothing.

this is the sender, it's taken almost straight from the example(i'm not using the if for the send, i don't understand why the example uses it, the: if(!driver.send), but that's apart):

#include <RH_ASK.h>
#ifdef RH_HAVE_HARDWARE_SPI
#include <SPI.h> // Not actually used but needed to compile
#endif

RH_ASK driver;

uint16_t data = 1023;

void setup()
{
#ifdef RH_HAVE_SERIAL
  Serial.begin(9600);	  // Debugging only
#endif
  if (!driver.init())
#ifdef RH_HAVE_SERIAL
    Serial.println("init failed");
#else
    ;
#endif
}

void loop()
{
  driver.send((uint8_t *)&data, strlen(data));
  driver.waitPacketSent();
  delay(1000);
}

the receiver:

#include <RH_ASK.h>
#ifdef RH_HAVE_HARDWARE_SPI
#include <SPI.h> // Not actually used but needed to compile
#endif

RH_ASK driver;

uint16_t data;

void setup()
{
#ifdef RH_HAVE_SERIAL
  Serial.begin(9600);	  // Debugging only
#endif
  if (!driver.init())
#ifdef RH_HAVE_SERIAL
    Serial.println("init failed");
#else
    ;
#endif
}

void loop()
{
  uint8_t datalen = sizeof(data);
  if (driver.recv((uint8_t*)&data, &datalen) && datalen == sizeof(data)) {
    uint16_t xyz = data;
    Serial.println(xyz);
  }
}

yet nothing is received.

another thing i don't quite understand is why the AND "driver.recv((uint8_t*)&data, &datalen) && datalen == sizeof(data)", ¿doesn't the receive already compares the data length before returning the valid value?, as per RH documentation, datalen will contain the actual length of the received value, so ¿why that second check?, it should always be matching.

It makes no sense!, Unless: let's say i receive one byte only, data gets that byte, the datalen is "1" due to that(taken care from the recv function) , it then compares "1" to... 2 because sizeof(data) is operating on the variable that's a uint16_t, ¿is this right?

and why it does the "uint8_t datalen = sizeof(data);" is for?, data is an int, so datalen is 2 in this case, always

edit: also tried moving the "uint16_t data;" declaration inside the loop for the receive, no difference

2

addendum:
So, i removed the length check on that receiver, and the serial console on the receiver shows: 14378

¿WTF?, where does that number came from

Another test:
If i move the "uint16_t data;" declaration to global instead of inside the loop, the receiver now shows 0

I changed the transmit sketch back to the default one, and now the receiver shows "25960".

edit 2:
Change the transmit value to "512", guess what?, receiver still shows 14378 being received

3

driver.send((uint8_t *)&data, strlen(data));

Why would you use strlen for an integer variable type?

4

gfvalvo:
driver.send((uint8_t *)&data, strlen(data));

Why would you use strlen for an integer variable type?

of ffs... that's what happens for reusing the example sketch instead of actually copying the .h file example!

¡that should've been a sizeof!

it's working perfectly now