I have a custom CC1352P board with the same schematics as that of the LaunchXL board. I modified the example program "rfPacketTx_CC1352P1_LAUNCHXL_tirtos_ccs" to perform the following tasks.
while(1)
{
//Set RF in RX mode
RF_CmdHandle ch = RF_postCmd(rfHandle, (RF_Op*) &RF_cmdPropRx_custom433_0, RF_PriorityNormal, &callbackRX, RF_EventRxEntryDone);
if(data in on UART)
{
ReadUartData();
//Cancel RF RX mode
RF_cancelCmd(rfHandle, ch, 0);
// Transmit data
RF_runCmd(rfHandle, (RF_Op*) &RF_cmdPropTx_custom433_0, RF_PriorityHighest, NULL, 0);
//Set RF chip to RX mode
ch = RF_postCmd(rfHandle, (RF_Op*) &RF_cmdPropRx_custom433_0, RF_PriorityNormal, &callbackRX, RF_EventRxEntryDone);
}
}
This is what the code does -
Set the chip in RX mode. If there is data on UART, cancel RX mode, transmit the data, and then set the chip to RX mode.
Configuration: 430 MHz frequency, GFSK 200 kbps, frequency deviation = 25 kHz, RBW: 273.1 kHz
Now, let us assume one-way transmission, i.e, the module is only transmitting.
Problem: As we observe on the spectrum analyzer, the transmission is fine for some time when there is continuous incoming data on uart. We observe GFSK transmission exactly at 430 MHz. After some time, we see additional peak power at 430 MHz - 3MHz = 427 MHz. The appearance of this peak is random. Sometimes, this problem is observed after 15 minutes of continuous transmission, sometimes after 2 hours. The problem can be solved by power resetting the chip.
The observed spectrum during the problem is shown below.
Does anyone know why there is another peak at Carrier-3MHz after some duration of transmission? Also, this is not reproducible frequently. Sometimes, the issue appears after 15mins, sometimes 2 hours, sometimes no issue.
