file MC1321XSRB:
void RadioInit(void) {
SPIDrvWrite(0x11,0x80FF); /* Eliminate Unlock Conditions due to L01 */
SPIDrvWrite(0x1B,0x8000); /* Disable TC1. */
SPIDrvWrite(0x1D,0x8000); /* Disable TC2. */
SPIDrvWrite(0x1F,0x8000); /* Disable TC3. */
SPIDrvWrite(0x21,0x8000); /* Disable TC4. */
SPIDrvWrite(0x07,0x4C00); /* Enable CLKo in Doze for externaal switch*/
.....
and
void RadioInit(void) {
SPIDrvWrite(0x11,0x80FF); /* Eliminate Unlock Conditions due to L01 */
SPIDrvWrite(0x1B,0x8000); /* Disable TC1. */
SPIDrvWrite(0x1D,0x8000); /* Disable TC2. */
SPIDrvWrite(0x1F,0x8000); /* Disable TC3. */
SPIDrvWrite(0x21,0x8000); /* Disable TC4. */
SPIDrvWrite(0x07,0x5E00); /* Enable CLKo in Doze for iinternaal switch*/
.....
But I think that using external switch is the beest way to gain best radio-performance.