Reed Kimble

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10 years, 8 months ago.

UDPSocket and Wifly Interface Requires Blocking

I cannot seem to get the socket.set_blocking(false, timeout) to work when using the Wifly interface.

If I set blocking to true on the socket, then I can receive UDP datagrams. However, if I try to set blocking to false with anything less than 1000 ms timeout, I do not receive any datagrams. And if I set the timeout to 1000ms or more, the socket seems to block forever, or at least I cannot get other code in the loop to run.

Here is the basic test code I'm working with (note this is a rework of code that was using TCP instead of UDP and the code was working):

#include "mbed.h"
#include "WiflyInterface.h"
#include "FRamIO.h"
#include "PinDetect.h"
#include "Interpreter.h"
#include <string>

DigitalOut LedYellow(LED4);
DigitalOut LedGreen(LED3);
DigitalOut LedBlue(LED2);
DigitalOut LedRed(LED1);

DigitalOut Output1(p30);
DigitalOut Output2(p29);
PinDetect Input1(p8, PullDown);
PinDetect Input2(p7, PullDown);
DigitalIn Button1(p25);
DigitalIn Button2(p26);

Serial pc(USBTX, USBRX);
FRamIO fRam(p28, p27, 0xA0, p24);

WiflyInterface wifly(p13, p14, NC, p5, "mynetwork", "mypassword", WPA);

int main() {
    wifly.init();
    wifly.connect();
    
    UDPSocket socket;
    
    socket.init();
    //socket.bind(1235);
    socket.set_blocking(false, 1000);
    Endpoint remoteTcp;
    remoteTcp.set_address("192.168.1.7", 1235);
    
    LedRed = 0;
    LedBlue = 1;
    LedGreen = 1;
    LedYellow = 1;
    
    char* address = wifly.getIPAddress();
    pc.printf("%s\n", address);
    
    char buffer[256];
    while(1) {
        if (pc.readable()) {
            pc.putc(pc.getc());
        }
        int bytesRead = socket.receiveFrom(remoteTcp, buffer, sizeof(buffer));
        if (bytesRead > 0) {
            pc.printf("read %i bytes\n", bytesRead);
            buffer[bytesRead] = '\0';
            pc.printf("%s\n", buffer);
        }
    }
}

Ultimately I need to be running a loop doing various work on each pass. One of the things I want to do on each pass is check for a received message, or possibly send a message. But there are other processes going on too so I can't sit around and wait forever for a UDP message; ideally I want to see if there is a message pending (wait no more than 1ms) and if not, check again on the next pass.

1 Answer

David Smart
10 years, 7 months ago.

Hi Reed,

I had some similar challenges with WiFly module and blocking mode. I ended up deriving my own version of both WiflyInterface and Wifly. And for a practical application, you can look at Smart-WiFly-Webserver where I use the mods I made.