rfEchoRx

Example Summary

In this example you will learn how to setup the radio to do bi-directional communication. The Echo RX example start off by putting the radio in receiver mode and waits for a packet to be transmitted. When it receives a packet it switches the radio to transmitter mode and re-transmits the received packet (echo). This example is meant to be used with the Echo TX example or SmartRF Studio. For every packet echo, CONFIG_PIN_RLED is toggled. The frequency and other RF settings can be modified using SmartRF Studio.

Board Specific Settings

  1. The default frequency is:
    • 2440 MHz on the LP_EM_CC2340R5 In order to change frequency, modify the FREQUENCY define in rfEchoRx.c.

Example Usage

The user will require two launchpads, one running rfEchoTx (Board_1), another running rfEchoRx (Board_2). Run Board_2 first, followed by Board_1. Board_1 is set to transmit a packet every second while Board_2 is set to receive the packet and then turnaround and transmit it after a delay of 100ms. CONFIG_PIN_GLED on Board_1 will toggle when it's able to successfully transmits a packet, and when it receives its echo. CONFIG_PIN_RLED on Board_2 will toggle when it receives a packet, and once again when it's able to re-transmit it (see [figure 1]).

perfect_echo_ref

If there is an issue in receiving a packet then CONFIG_PIN_GLED on Board_2 is toggled while CONFIG_PIN_RLED is cleared, to indicate an error condition

echo_error_ref

Application Design Details

This examples consists of a single task and the exported SmartRF Studio radio settings.

When the task is executed it:

  1. Configures the radio for Proprietary mode
  2. Get access to the radio via the RCL drivers RCL_open
  3. Configure the proprietary RCL_CmdGenericTx and RCL_CmdGenericRx commands.
  4. Set the output power using TX_POWER.
  5. Set the frequency by editing the command's rfFrequency attribute
  6. Run the RCL_CmdGenericRx command and wait for a packet to be transmitted. The receive command is chained with a transmit command, RCL_CmdGenericTx, which runs once a packet is received
  7. When a packet is successfully received CONFIG_PIN_RLED is toggled, the radio switches over to the transmit mode and schedules the packet for transmission immediately
  8. If there is an issue either with the receive or transmit, an error, both LEDs are set
  9. The devices repeat steps 6-8 forever.

Switching PHYs

The PHY used for TX operations can be configured in SysConfig by opening the rfPacketTx.syscfg file and navigating to the "Custom" RF Stack. The PHY used can be selected from the provided drop downs. The example only supports one phy at a time.

In addition, several register fields must be exposed as defines so that the example can appropriately set the length field in the packet header. This can be accomplished by navigating in SysConfig to the Custom RF Stack --> Your Selected PHY --> Code Export Configuration --> Register Field Defines and setting it's value to "PBE_GENERIC_RAM_LENCFG_LENPOS,PBE_GENERIC_RAM_LENCFG_NUMLENBITS".