Connecting to ttn with STM32

End Devices (Nodes)
1

Summary
I want to connect an stm32L4 with RFM95) to TTN using ABP mode. This is my lorawan code ( am using the AES and sx1276 libraries )

Logs
<#include “lorawan.h”
#include “main.h”
#include “Encrypt_V31.h”
#include “AES-128_V10.h”
#include “SX1276.h”
#include <stdio.h>
#include <string.h>
#include “math.h”

static uint8_t Buffer[256]; // Global buffer for data

void lorawan_init(lorawan_t *lorawan, SX1276_t *sx1276) {
lorawan->sx1276 = sx1276;
}

void lorawan_set_keys(lorawan_t *lorawan, uint8_t NwkSkey, uint8_t AppSkey, uint8_t DevAddr) {
lorawan->NwkSkey = NwkSkey;
lorawan->AppSkey = AppSkey;
lorawan->DevAddr = DevAddr;
}

uint32_t lorawan_send_data(lorawan_t *lorawan, uint8_t *data, unsigned len, uint16_t frame_counter_up) {
unsigned char i;
unsigned char Direction = 0x00; // Direction of frame is up
unsigned char MIC[4];
unsigned char Mac_Header = 0x40; // Unconfirmed data up
unsigned char Frame_Control = 0x00;
unsigned char Frame_Port = 0x01;

// Test flag: if all data[i] == i then don't send but print encrypted data
int is_test = 1;
for (i = 0; i < len; i++) {
    if (data[i] != i) {
        is_test = 0;
        break;
    }
}

// Encrypt the payload
Encrypt_Payload(data, len, frame_counter_up, Direction, lorawan->AppSkey, lorawan->DevAddr);
Println("Data encrypted");

// Build the radio package
Buffer[0] = Mac_Header;
Buffer[1] = lorawan->DevAddr[3];
Buffer[2] = lorawan->DevAddr[2];
Buffer[3] = lorawan->DevAddr[1];
Buffer[4] = lorawan->DevAddr[0];
Buffer[5] = Frame_Control;
Buffer[6] = (frame_counter_up & 0x00FF);
Buffer[7] = ((frame_counter_up >> 8) & 0x00FF);
Buffer[8] = Frame_Port;

unsigned char SX1276_Package_Length = 9;

for (i = 0; i < len; i++) {
    Buffer[SX1276_Package_Length + i] = data[i];
}

SX1276_Package_Length += len;

// Calculate MIC
Calculate_MIC(Buffer, MIC, SX1276_Package_Length, frame_counter_up, Direction, lorawan->NwkSkey, lorawan->DevAddr);
Println("MIC calculated");

// Print test package
if (is_test) {
    Println("Encrypted data:");
    for (i = 0; i < SX1276_Package_Length; i++) {
        char temp[10];
        sprintf(temp, "%02X ", Buffer[i]);
        Println(temp);
    }
    return 0;
}

// Append MIC to the buffer
for (i = 0; i < 4; i++) {
    Buffer[SX1276_Package_Length + i] = MIC[i];
}

SX1276_Package_Length += 4;

// Transmit the package
uint32_t result = SX1276_transmit(lorawan->sx1276, Buffer, SX1276_Package_Length, SX1276_DEFAULT_TIMEOUT);
if (result != 0) {
    Println("Transmission failed");
} else {
    Println("Transmission succeeded");
}
return result;

}

Hardware
SX1276 + STM32l476RCT

2

There are already working LW stacks that you can run on STM32 - including the one that was directly above your first post - what was wrong with that?

Overall, please do not develop a stack against the TTN community servers - there are enough problems with comms in Paris at the moment without someone trying to write complicated software and test against the shared servers.

One key element when asking for help - actually say what the problem is - you’ve provided us with the hardware, the libraries & your code but you haven’t actually said what the issue is.

3

Your code does not implement the mandatory downlink and MAC command handling. If you do not implement that you will effectively be DoSsing the gateways that receive and forward your uplinks.