Jakub Siska

Important changes to forums and questions

All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.

9 years, 2 months ago.

Transmitting in FSK mode

I am using this transmitting code in fsk mode

tsx127x transmitter

#include "sx127x_fsk.h"
#include "mbed.h"
SX127x kom(PTD6, PTD7, PTD5, PTD4, PTA6, PTA7, PTC16, PTC13, PTA14);
SX127x_fsk Fsk(kom);

Serial pc(USBTX, USBRX);

int main()
{
    Fsk.enable();
    Fsk.init(); 
    pc.baud(115200);
    for(unsigned i = 0; i < 8; i++)
    {
        kom.tx_buf[i] = 0xf;
        pc.printf("%x", kom.tx_buf[i]);
    }
    Fsk.start_tx(8);
 while(true)
    {
        while(Fsk.service() != SERVICE_TX_DONE);
       	Fsk.start_tx(8);
    }
        
}

and it doesn't transmit anything. I have checked registers and fifo is empty all the time even though there is data in the buffer. Do you see what is wrong?

Question relating to:

Last updated: 10 Jul 2020
Driver library for SX1272/SX1276 transceivers Radio, transceiver

1 Answer

wayne roberts
9 years, 2 months ago.

I had to add a small delay on line 22 before the 2nd start_tx(). Just a millisecond or two is needed, but you must transmit slow enough for receiver side to keep up packet processing.

I have had this delay (50ms) but this doesnt work as well. I am not interested in the receiver yet because from usb dongle DVB-T sniffer I havent seen radio is anything transmitting.

posted by Jakub Siska 12 Feb 2015