GPIO not fast enough for RF transmitter?

Question

I'm trying to control a 315MHz RF socket using the RCSwitch library. I tested with an Arduino and it worked 100% of the time but when porting over to a pi zero I can only get it to correctly turn on / off about 1 in every 10-15 tries.

I'm not sure if there is a problem with my code, the library or just the pi not being fast enough to handle sending the data properly.

Here's my current code:

#include <wiringPi.h>
#include "RCSwitch.h>

int main(int argc, char** argv)
{
    wiringPiSetup();

    RCSwitch sw;
    sw.enableTransmit(0);
    sw.setProtocol(6);
    sw.send(16777173, 24);
}

edit: It definitely appears to be at least partly a performance problem, compiling with -O2 ups the success rate to around 1/3.

Answer 1

The problem was with how the wiringPi handles sleeping. Actual sleeps appear to not be accurate enough so a wait loop has to be used.

The solution was to change the call to the delayMicroseconds function in RCSwitch::transmit to delayMicrosecondsHard which is defined in wiringPi.c but not exported so I copied the implementation into RCSwitch.