Sometime i can get downlink data but sometime i also can not get and my issue here : my old issue.
But right now , i can get something data from gateway , but i don’t know what is that . Can anybody decode it to me?
My code in Arduino from this Code from matthijskooijman
And i change a little bit inside function EV_TXCOMPLETE() to this
if (LMIC.dataLen) {
Serial.println(F(“Received “));
Serial.println(LMIC.dataLen);
Serial.println(F(” bytes of payload”));
Serial.print(“txCnt :”); Serial.println(LMIC.txCnt);
Serial.print(“txrxFlags :”); Serial.println(LMIC.txrxFlags);
Serial.print(“dataBeg :”); Serial.println(LMIC.dataBeg);
for (int i = 0; i < LMIC.dataLen; i++) {
if (LMIC.frame[LMIC.dataBeg + i] < 0x10) {
Serial.print(F(“0”));
}
Serial.print(LMIC.frame[LMIC.dataBeg + i], HEX);
}
}
This is exactly what i get , what is that number sequence 
I find out the page to decode , i don’t understand but the appEUI and devEUI not as same as with my appEUI,devEUI
This is the picture :
Well, for one thing, your filtering of the data bytes and zeroing those with small value will corrupt it. You need to display the entire packet as hex if you want to make sense of it elsewhere.
You probably also want to add or enable debugging in the packet decoding failure and success paths so you see if you get a MIC mismatch, etc.
I copy that code from ttn forum ^^, i don’t know which function can show entire the data . If i can show the data , but how can i send the dât as i want ex( hello world ,…) , this downlink just send the information of gateway right?
Well, you need to find a non-distorting hexdump routine. And it needs to print all values and it needs to print each with two digits under all conditions, ie leading zeros must not be removed.
Arduino tends to make it easy to start a project but then a comparatively hard to get the exact behavior you need.
