CC1352P: how to send data from collector to a specific sensor in a 15.4 network FH Low Latency Broadcast mode

Hi Zhiyong,

the communication from collector to sensor is implemented using broadcast transmissions only.

The broadcast message is sent periodically (broadcast interval) by the collector. The event responsible is the COLLECTOR_BROADCAST_TIMEOUT_EVT and the event handling that you shared above.

The default message format is as below and you can change it in smgs.h (remember to change it on collector and sensor).

All sensors receive all broadcast messages and use them as heartbeat to check if they are still connected to the collector.

All sensors check after receiving the broadcast message if the Destination Device Address is the same as their own device address. If so, they process the command.

The sensor processes the broadcast message in sensor.c -> processBroadcastCtrlMsg() below.

To address now a specific sensor you need to attach it's device address to the broadcast message. This will trigger the Command event when the sensor receives it.

An example on how this is done is implemented on the collector. When pressing button 1 of the collector it will append the device address of the first sensor in the network and you will see the Green LED of the sensor toggle when it receives the command. With button 2 of the collector you can address one by one all the sensors in the network and observe the same LED toggle. (Checkout collector.c -> COLLECTOR_BROADCAST_CAMCMD_EVT)

Each of the commands is acknowledged by the sensors and the collectors green LED toggles when it receives the acknowledgement.

Kind regards,
Theo

Hi Zhiyong,

1. Currently camCmd = 0x01 is used to trigger the camera command on the sensor side. You could reuse this, for instance with a different value 0x02 to trigger your command.

sensor.c

                /* process camera commands */
                if(camCmd == 0x1) //--> This is the camCmd
                {
                    /* send the acknowledgment message */
                    uint8_t buffer[SMSGS_TOGGLE_LED_RESPONSE_MSG_LEN];
                    uint8_t *pBuf = buffer;

                    *pBuf = (uint8_t)Smsgs_cmdIds_toggleLedRsp;

                    Sensor_sendMsg(Smsgs_cmdIds_toggleLedRsp,
                                    &pDataInd->srcAddr, true,
                                    SMSGS_TOGGLE_LED_RESPONSE_MSG_LEN,
                                    buffer);

                    Util_setEvent(&Sensor_events, SENSOR_BROADCAST_CAMCMD_EVT);
                }
            }

collector.c

                /* Build the message */
                if(sendCamCmd)
                {
                    *pBuf++ = (uint8_t)Smgs_cmdIds_broadcastCtrlMsg;
                    *pBuf++ = Util_loUint16(destDevAddr);
                    *pBuf++ = Util_hiUint16(destDevAddr);
                    *pBuf = 0x1; // -> this is the camCmd
                    sendCamCmd -= 1;
                }

If you needed an additional payload besides the command, you should increase (smsgs.h) SMSGS_BROADCAST_CMD_LENGTH and add an additional member to  the struct Smsgs_broadcastcmdmsg_t. And then you populate *pBuf from the previous code snippet.

2. 5 to 10 seconds broads interval should be fine. Remember you should also change  LOW_LATENCY_BROADCAST_CONFIGURATION_TIMEOUT (sensor.c) to double the broadcast interval as explained in  the user manual . I'll check on what is the practical limit.