LILYGO® TTGO T-Watch GPS + Lora (S76G) watch expansion card

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New LilyGO S76G (GNSS + LoRa) product on AliExpress:

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Did anyone ever get this impulse thing working?

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No, not likely to work with meshtastic

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I just found the T-Impulse too and ended up on this thread. I’d be interested to know why it is not viable as Meshtastic device.

What is current best hardware option of a dog collar based meshtastic node?

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STM32 Chip is not yet supported, not enough ram.

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I have a couple T-Impulse devices i’m looking into making a stripped down firmware that only sends location messages and doesn’t wait for an ACK. I see there’s an arduino library for using the protocol buffers. Wondering if anyone has used that and has experience using the protobufs (or maybe simply the C structs after compiling)?

Glad I found this thread!

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The t-watch is going to be an easier target
https://a.aliexpress.com/_m0fjxWu

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looks great, but i can’t see that it has GPS.

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GPS is a lot of power draw for that tiny battery, probably best to let your phone do that part.

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Hey, did you ever make any progress with this idea? I’m contemplating the exact same approach – making a meshtashtic-light firmware.

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Wondering the same, if it could just work like a low jack, sending GPS coordinates to mesh network, have it on your managed meshtastic devices and only tx GPS over radio

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Maybe this group can help. I have the following code which I think is almost there. I’m still struggling with how to construct the packets. This requires the nano_pb library to be build in your environment FYI

    gps_loop();
    TinyGPSPlus *gps = getGPS();
    meshtastic_Position pos = meshtastic_Position_init_zero;
    pos.latitude_i = gps->location.lat();
    pos.longitude_i = gps->location.lng();
    pos.altitude = gps->altitude.meters();
    pos.time = gps->time.value(); //uint32_t time
    pos.location_source = meshtastic_Position_LocSource_LOC_EXTERNAL; //meshtastic_Position_LocSource location_source,
    pos.altitude_source = meshtastic_Position_AltSource_ALT_EXTERNAL; //meshtastic_Position_AltSource altitude_source;
    pos.timestamp = gps->time.value(); //uint32_t timestamp;
    pos.timestamp_millis_adjust = gps->time.value(); //int32_t timestamp_millis_adjust;
    pos.altitude_hae = gps->altitude.meters(); //int32_t altitude_hae;
    pos.altitude_geoidal_separation = gps->altitude.meters(); //int32_t altitude_geoidal_separation;
    pos.PDOP = gps->hdop.hdop(); //uint32_t PDOP;
    pos.HDOP = gps->hdop.hdop(); //uint32_t HDOP;
    pos.VDOP = gps->hdop.hdop(); //uint32_t VDOP;
    pos.gps_accuracy = gps->satellites.value(); //uint32_t gps_accuracy;
    pos.ground_speed = gps->speed.mps(); //uint32_t ground_speed;
    pos.ground_track = gps->course.deg(); //uint32_t ground_track;
    pos.fix_quality = gps->satellites.value(); //uint32_t fix_quality;
    pos.fix_type = 0; //uint32_t fix_type;
    pos.sats_in_view = gps->satellites.value(); //uint32_t sats_in_view;
    pos.sensor_id = 1; //uint32_t sensor_id;
    pos.next_update = 1; //uint32_t next_update,
    pos.seq_number = seqnum++; //uint32_t seq_number
    getOled()->setContrast(0x00);
    getOled()->clearBuffer();
    getOled()->setFontMode(1); // Transparent
    getOled()->setFontDirection(0);
    getOled()->setFont(u8g2_font_fub14_tf);
    sprintf(oledbuf, "%d", gps->time.value());
    getOled()->drawStr(2, 18, oledbuf);
    getOled()->sendBuffer();

    
    // meshtastic_Data_payload_t payload = {
    //   sizeof(pos),
    //   (uint8_t)&pos
    // };

    meshtastic_Data data_pkt = meshtastic_Data_init_default;
    data_pkt.dest = 0xFFFFFFFF;
    data_pkt.source = 0x00000001;
    data_pkt.want_response = false;
    data_pkt.payload.size = sizeof(pos);
    memcpy(data_pkt.payload.bytes, &pos, data_pkt.payload.size);
    meshtastic_MeshPacket packet = meshtastic_MeshPacket_init_zero;
    packet.to =  0xFFFFFFFF;
    packet.from = 0x00000001;
    packet.channel = 3;
    packet.want_ack = false;
    packet.which_payload_variant = meshtastic_MeshPacket_decoded_tag;
    packet.decoded = data_pkt;

    Serial.println(sizeof(data_pkt));

    /* Create a stream that will write to our buffer. */
    uint8_t buffer[sizeof(data_pkt)];
    pb_ostream_t stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
    pb_encode(&stream, meshtastic_Data_fields, &packet);
    if (isrReceived) {
    setRadioDirection(false);
    }
    delay(100);
    LoRa.beginPacket();
    uint8_t toSend[sizeof(stream)];
    memcpy(&toSend, &stream, sizeof(stream));
    LoRa.write(toSend, sizeof(stream));
    // stalls here!!!!.************************************************************
    LoRa.endPacket();