1. Test purpose
Received Signal Strength Indicator (RSSI) is a measurement of the power level of the received radio signal.
The TX/RX page allows user to establish a transmission between emitter and receiver and to measure & display dynamically RSSI on a chart.
2. Explaining the dashboard
The RXTX dashboard is divided in three areas :
- First group for TX transmission that allows the user to choose the RF frequency and the power level of emission (between -9 to 22 dBm). User can start and stop emission with the buttons. when board is connected, the LED is green. When transmission is ongoing, the signal indicator is green.
- Second group for RX reception that allows the user to choose the RF frequency. User can start and stop reception. when reception is started, the signal icon is green.
- The third area is showing the RSSI level in a gauge and a chart that is refreshed each 250 ms when reception is started.
3. Explaining the flow
The RXTX flow is a combination of TX & RX flows. TX flow is in charge of handling emission of signal while RX flow is handling reception.
The emitter must be connected to Serial Port A. The receiver must be connected to Serial Port B.
3.1. TX flow
TX flow manages the sequence of AT commands to the emitter. A finite state machine (FSM) is used to manage the sequence of AT command and target response. The parameters (RF Frequency and TX Power) are stored in flow variable when they are edited. The FSM status and transitions are corresponding to the normal sequence of AT command and abnormal response from target is also handled. The steps are to configure the board with stored parematers, and then start transmission. when stop button is pressed, board is stopped and FSM goes to STOPPED state. The LED indicating that the TX board is connected to the application is also managed by this flow.
3.2. RX flow
RX flow manages the sequence of AT commands to the receiver. A finite state machine (FSM) is used to manage the sequence and the target response. The FSM configures the board, then starts a first RSSI measurement. After each measurements, the flow waits 250 ms and then starts a new measurement. (This time between measurements can be changed in the flow with the delay node). The LED indicating that the RX board is connected to the application is also managed by this flow. The measurement results are decoded and displayed in the "RSSI" gauge and in the "RSSI" chart.
4. AT commands for TX RX commands
AT commands listed below are used by emitter and receiver flows
4.1. Emitter :
ATZ Reset the board
AT+TCONF[=freq:pow:bw:sf:cr:lna:pa][=868000000:14:4:12:4/5:0:0:1:16:25000:2:3] for example. Sets the configuration for RF test.
AT+TTONE Start the TX transmission
AT+TOFF Stop the TX transmission
4.2. Receiver:
AT+Z Reset
AT+TCONF[=freq:pow:bw:sf:cr:lna:pa][=868000000:14:4:12:4/5:0:0:1:16:25000:2:3] for example. Sets the configuraiton LoRa RF test.
AT+TRRSSI Start the RX reception and RSSI measurement
AT+TOFF Stop the RX reception