FUOTA implementation for Heltec ESP32 using AWS IoT Core

Question

Hi everyone,

I'm currently working on implementing Firmware Over The Air (FUOTA) updates for a Heltec ESP32-S3 v3 device using AWS IoT Core for LoRaWAN FUOTA. I’m encountering some challenges and would appreciate any guidance or insights the community can offer.

Here's a detailed breakdown of the issues I'm encountering along with the information I have:

**1.LoRaWAN Application Layer Clock Synchronization:** 
My initial focus has been on achieving LoRaWAN Application Layer Clock Synchronization using functions provided by Heltec's documentation. After successfully joining the network, I've observed the following results in my console:

```
joined
Unix time: 9.641
This uplink added time req.
confirmed uplink sending ...
Once device time updated, this function run
received unconfirmed downlink: rssi = -69, snr = 9, datarate = 5
Unix time: 1716901023.529
confirmed uplink sending ...
received unconfirmed downlink: rssi = -68, snr = 9, datarate = 5
Unix time: 1716901039.325
```

While this indicates partial success in clock synchronization, I'm uncertain about its completeness. Any insights or recommendations on improving this process would be highly appreciated.

**2. Multicast Group Setup:** 
Moving forward, configuring multicast groups on my device has proven to be challenging. Although Heltec's documentation indicates the use of multicast group addresses, I couldn't find this crucial information within the downlink message or the console provided by AWS IoT Core.

The provided code by Heltec (https://github.com/HelTecAutomation/Heltec_ESP32/blob/master/examples/LoRaWAN/LoRaWanMulticast/LoRaWanMulticast.ino)
In the network analyser, I noted three downlink messages for the multicast group join, which I selected as an example:

```json
{
     ....
    "WirelessMetadata": {
        "isPublicNetwork": false,
        "fPort": 200,
        "lorawanGateways": [
            {
                "gatewayEui": "XXXXX",
                "rssi": -99,
                "snr": 4.25,
                "wirelessGatewayId": ""
            }
        ],
        "dataRate": 0,
        "applicationInfo": {
            "multicastGroupId": "933aa82a-a2d5-7777-8d8d-398334d7409f",
            "applicationCommandType": "PackageVersionReq (Multicast)"
        },
        "devEui": "XXXXXXXXX5b",
        "mType": "UNCONFIRMED_DATA_DOWN",
        "frequency": 923300000,
        "timestamp": "2024-06-04T11:28:54.646101554Z"
    },
    "MessageId": "feede57e-4ddd-49b4-b527-08274e1e2ee4"
}
```
How can I set up multicast groups for ESP32 devices ?

**3. Firmware Fragmentation Setup:** 
In addition to multicast group configuration, I need to implement firmware fragmentation to ensure secure firmware transportation. Unfortunately, the library I'm using for LoRaWAN communication lacks support for ESP32 series devices, leaving me uncertain about proceeding with fragmentation. Has anyone encountered similar challenges or found alternative solutions for implementing FUOTA on ESP32 devices?

Thanks.

Greg_B · Answer

Hi. AWS IoT Core for LoRaWAN implements clock synchronization, multicast and FUOTA as per the LoRaWAN specifications. As detailed here: https://docs.aws.amazon.com/iot-wireless/latest/developerguide/lorawan-mc-fuota-overview.html. Your device needs to comply with those specifications.

I'm not familiar with Heltec or the software environment at your disposal. In general, I would recommend you print all LoRaWAN commands and responses (and MAC commands and responses) to your terminal, so you can see the message flow, and see when and where your device is not complying.

[LoRaMAC-node](https://github.com/Lora-net/LoRaMac-node) is a reference implementation that includes all of the features you're interested in. There's no existing port for ESP32, but there is a porting guide: https://stackforce.github.io/LoRaMac-doc/LoRaMac-doc-v4.7.0/_p_o_r_t_i_n_g__g_u_i_d_e.html

FUOTA implementation for Heltec ESP32 using AWS IoT Core

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