PA_PD是什么意思？

Other Parts Discussed in Thread: SIMPLICITI

查看simpliciTI的协议栈里面射频发送的源码，CCA发送这里我有一段代码移植不明白

#define MRFI_CONFIG_GDO0_AS_PAPD_SIGNAL()     mrfiSpiWriteReg(IOCFG0, MRFI_GDO_PA_PD)

/* For CCA algorithm, we need to know the transition from the RX state to
* the TX state. There is no need for SYNC signal in this logic. So we
* can re-configure the GDO_0 output from the radio to be PA_PD signal
* instead of the SYNC signal.
* Since both SYNC and PA_PD are used as falling edge interrupts, we
* don't need to reconfigure the MCU input.
*/

MRFI_CONFIG_GDO0_AS_PAPD_SIGNAL();

把GDOx_CFG[5:0]配置成0x1B，PA_PD。这里我一直不明白，这个功能是否是实现了，自动TX检测发送？发送成功后GDO0会出现电平的翻转

跪求TI技术解答！