libmDot-mbed5 Maximum payload size always 11 bytes

[Huo Chen]

Hi,

I tried to move my previous application to libmDot-mbed5. I first set the setTxDataRate to SF_9 (or other spreading factor which allow more payload size than 11 bytes). Then I use update_ota_config_name_phrase() in dot-util.h to connect my mdot to gateway. The problem is, no matter what data rate I choose, I always get the messge: Data exceeds datarate max payload. Is this a bug or am I doing something wrong?

PS: The data I want to send is “Hello World!” which has 12 bytes.

Best

[Mike Fiore]

Huo,

You can see from the source of update_ota_config_name_phrase() in dot_util.cpp that that function does not change the tx datarate. However, all the examples in Dot-Examples do default the configuration during initialization – if you are adding code to set the tx datarate before that default happens, that could explain the issue. Can you post your complete source code?

Cheers,

Mike

[Huo Chen]

Here is my code:

mDot* dot = NULL;

Serial pc(USBTX, USBRX);

int main()
{

    RadioEvent events;

    pc.baud(115200);

    mts::MTSLog::setLogLevel(mts::MTSLog::TRACE_LEVEL);
    
    dot = mDot::getInstance();

    dot->setEvents(&events);
	
    if (!dot->getStandbyFlag()) {

        logInfo("mbed-os library version: %d", MBED_LIBRARY_VERSION);
        dot->resetConfig();
        dot->resetNetworkSession();
        dot->setLogLevel(mts::MTSLog::INFO_LEVEL);

        if (dot->getJoinMode() != mDot::AUTO_OTA) {
            logInfo("changing network join mode to AUTO_OTA");
            if (dot->setJoinMode(mDot::AUTO_OTA) != mDot::MDOT_OK) {
                logError("failed to set network join mode to AUTO_OTA");
            }
        }
        update_ota_config_name_phrase(network_name, network_passphrase,     frequency_sub_band, public_network, ack);
        update_network_link_check_config(3, 5);			
        dot->setTxDataRate(mDot::DR1);
        logInfo("saving configuration");
        if (!dot->saveConfig()) {
            logError("failed to save configuration");
        }
        display_config();
        if (!dot->getNetworkJoinStatus()) {
            join_network();
        }
        send_data(get_fake_data());
    }
}

And when display_config() printing out the information. Tx data rate is set correctly.

[INFO] TX datarate -------------- DR1

• This reply was modified 7 years, 5 months ago by Huo Chen.
• This reply was modified 7 years, 5 months ago by Huo Chen.

[Mike Fiore]

Huo,

Can you post the contents of your get_fake_data() function?

Also, all of your functionality is within the if (!dot->getStandbyFlag()) block. That may not be what you intended.

Cheers,

Mike

[Huo Chen]

Here is what get_fake_data() is:

std::vector<uint8_t> get_fake_data(void) {
	std::string fake_data="Hello World!";
	std::vector<uint8_t> data_send;
	for (std::string::iterator it=fake_data.begin(); it!=fake_data.end(); it++) {
		data_send.push_back(*it);
	}
	return data_send;
}

[Huo Chen]

I also tried to use the code from previous version, but it still didn’t work

int main() {
	
        int32_t ret;
	std::vector<uint8_t> data;
	std::string data_str = "hello world!";
        pc.baud(115200);
        mts::MTSLog::setLogLevel(mts::MTSLog::TRACE_LEVEL);
        dot = mDot::getInstance();
        logInfo("setting frequency sub band");
        if ((ret = dot->setFrequencySubBand(config_frequency_sub_band)) !=     mDot::MDOT_OK) {
                logError("failed to set frequency sub band %d:%s", ret,    mDot::getReturnCodeString(ret).c_str());
    }
    
        logInfo("setting network name");
        if ((ret = dot->setNetworkName(config_network_name)) != mDot::MDOT_OK) {
                logError("failed to set network name %d:%s", ret, mDot::getReturnCodeString(ret).c_str());
    }
    
        logInfo("setting network password");
        if ((ret = dot->setNetworkPassphrase(config_network_pass)) != mDot::MDOT_OK) {
                 logError("failed to set network password %d:%s", ret, mDot::getReturnCodeString(ret).c_str());
    }
    
        logInfo("setting TX spreading factor");
        if ((ret = dot->setTxDataRate(mDot::SF_10)) != mDot::MDOT_OK) {
                logError("failed to set TX datarate %d:%s", ret, mDot::getReturnCodeString(ret).c_str());
    }
    
        logInfo("enabling ACKs");
        if ((ret = dot->setAck(1)) != mDot::MDOT_OK) {
                logError("failed to enable ACKs %d:%s", ret, mDot::getReturnCodeString(ret).c_str());
    }
    
        logInfo("setting join mode to AUTO_OTA");
        if ((ret = dot->setJoinMode(mDot::AUTO_OTA)) != mDot::MDOT_OK) {
                logError("failed to set join mode %d:%s", ret, mDot::getReturnCodeString(ret).c_str());
    }
    
        logInfo("saving config");
        if (! dot->saveConfig()) {
                logError("failed to save configuration");
    }

        for (std::string::iterator it = data_str.begin(); it != data_str.end(); it++)
        data.push_back((uint8_t) *it);

        if (!dot->getNetworkJoinStatus()) {
                logInfo("network not joined, joining network");
                if ((ret = dot->joinNetwork()) != mDot::MDOT_OK) {
                        logError("failed to join network %d:%s", ret, mDot::getReturnCodeString(ret).c_str());
        }
    }
        if (dot->getNetworkJoinStatus()) {

                if ((ret = dot->send(data)) != mDot::MDOT_OK) {
                        logError("failed to send %d:%s", ret, mDot::getReturnCodeString(ret).c_str());
        } else {
                logInfo("successfully sent data to gateway");
        }
    }

    wait_ms(2000);

    return 0;
}

[Mike Fiore]

Huo,

I have verified this issue. We will get this fixed in the next release. A simple workaround is to set the TX datarate after the join is successful.

The following block of code can be used to change the data rate after joining.

        if (dot->getTxDataRate() != mDot::DR1) {
            logInfo("changing TX datarate to DR1");
            if (dot->setTxDataRate(mDot::DR1) != mDot::MDOT_OK) {
                logError("failed to set TX datarate to DR1");
            }
        }

I apologize for the trouble this has caused you. We will get it fixed in the next mDot release.

Cheers,

Mike

[Mike Fiore]

Huo,

The latest version of libmDot-dev-mbed5 will also have this fix if you’d prefer to use that until the next libmDot-mbed5 release instead of implementing the workaround.

https://developer.mbed.org/teams/MultiTech/code/libmDot-dev-mbed5/

Cheers,

Mike

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