mDot P2P mode, failed to set tx datarate

[Yi Wei]

Hi,

I’m working on a project which needs to be able to send lora packet in peer to peer mode as long range as possible. We are using AU915 Plan, we found that in the latest release, the Data rate 0-6 were supported for the AU915 plan, but we still can’t set the data rate correctly, here are the debug information:

[INFO] changing TX frequency from 0 to 915500000
[INFO] changing TX datarate from 8 to 0
[ERROR] TX data rate 1 invalid
[ERROR] failed to set TX datarate to 0

We only modified minimum bits in the latest Peer to peer example, for example change data rate to 0 or 1 and send a packet at 16 bytes long. The libraries are mdot-library revision 3.1.0 and mbed-os revision mbed-os-5.7.7 default tip.

Does anyone know if the latest library support data rate 0 or is ADP supported in peer to peer mode?

The reason why we had to move to the latest firmware is because when using the old firware mdot-library (3.0.0) and mbed-os (5.4.7), the data rate 0 only allow 11 bytes payload to be transmitted in peer to peer mode.  According to the specs, we should be able to easily transmit 51 bytes right?

Thanks in advance.

Regards,

Yi

[Ryan Klaassen]

In AU915 peer to peer, the valid datarates are 8-13.

[Yi Wei]

OK thanks. I was able to use data rate 0 in old firmware, but it only allows 11 bytes, is that data rate valid and can I reach the longest range with that being set? Is data rate 0 – 3 going to be supported in the AU915 plan in the future as I saw there are some comments in the peer to peer example code saying that data rate 0-3 should be available under AU915 plan.

        case lora::ChannelPlan::AU915:
            // 500kHz channels achieve highest throughput
            // DR_8 : SF12 @ 500kHz
            // DR_9 : SF11 @ 500kHz
            // DR_10 : SF10 @ 500kHz
            // DR_11 : SF9 @ 500kHz
            // DR_12 : SF8 @ 500kHz
            // DR_13 : SF7 @ 500kHz
            // DR_0 - DR_3 (125kHz channels) available but much slower
            tx_frequency = 915500000;
            tx_datarate = lora::DR_0;
            // 915 bands have no duty cycle restrictions, set tx power to max
            tx_power = 20;
            break;

[Jason Reiss]

125 khz channels may not be allowed by regulation without frequency hopping.

Since P2P uses a single frequency there is no hopping.

Check local regulations for ISM band.

AU borrows from FCC.

[Author]

Posts