After setting the pin TRX_PIN_SLP_TR = HIGH, the radio transceiver delivers a specified number of additional clock cycles (refer to tTR3) on the pin TRX_PIN_CLKM before it reaches the SLEEP state. More details about the usage of pin TRX_PIN_SLP_TR can be found in section 6.5(Sleep/Wake-up and Transmit Signal) of the AT86RF231 datasheet.
Note:
If a CLKM frequency less or equal to 250 kHz is selected, the clock signal at pin TRX_PIN_CLKM will be turned off immediately.