SDK version 4.10 or newer has to be used. TCXO usage is enabled in syscfg. Under TI Devices → Device Configuration, select External 48MHz TCXO as HF Clock source. When TCXO is selected as source, select the TCXO type and the TCXO Max Startup Time. It is important that this time is set correctly. If a too short time is set, the chip could attempt to switch to the TCXO before this is stable, which again could cause the chip to malfunction.

When a TCXO is used, the internal load capacitors have to be reduced to avoid loading the TCXO. The required setting will be dependent on the selected TCXO. Turning off the capacitor array could cause the output swing to be too large from some TCXOs. In these cases, the capacitor in the capacitor array will help reducing the voltage swing. The capacitor array should be set to a value where the swing on the X48M_P is within the value set in the CC13x2 data sheet, both for minimum and maximum swing. Care has to be taken when doing the measurement to avoid that the measurement does not increase the load on this node, which will impact the measurement result.

In syscfg go to TI Devices → Device Configuration and tick the box next to “Enable XOSC Cap array modification” and set the wanted value.

The power driver contains a function hook PowerCC26X2_Config.enableTCXOFxn that has to be added to the code. If this function is not defined, the code will compile but it will hang when the system requests the radio to turn on. The function hook makes it possible to power the TCXO from a DIO and turn off the TCXO when the CC13x2 is in standby and turn it on again in time for a RF operation.

The following code snippet show how this function can look when the TCXO is powered by a DIO:

void Power_enableTCXO(bool turnOn) 
{ 
    if ( turnOn ) { 
        // Set corresponding DIO high to enable the TCXO 
        GPIO_write(GPIO_TCXO_PIN, 1); 
    } 
    else { 
        // Set the corresponding DIO low to disable the TCXO 
        GPIO_write(GPIO_TCXO_PIN, 0); 
    } 
}

SmartRF Studio 2.17 or earlier does not support TCXO.