CC2530 Send data to USB

You cannot use the USB connector on the SmartRF05EB board for sending data from the CC2530EM, as it is for running the debugger. While debugging via the IAR to this H/W, you can send debug messages, but these are very slow and interfere with real-time ISR handling.

But in the CC2530ZDK kit that you have you will see one, small USB dongle, the CC2531USB-Dongle board. Note that this board has a CC2531 vice a CC2530, and the CC2531 does have a USB peripheral as part of the SOC and you can implement any USB class that you want. Most usable for your example is to implement the USB CDC class so that the dongle shows up on the Windows PC as a COM port that you can open and perform read/write like with any serial port. There are already HAL drivers that implement this virtual COM port on the SOC for you. 

Yes, Z-Stack 2.5.1 adds this command to control Tx power via the MT (monitor / test) serial API:  MT_SYS_SET_TX_POWER

When compiling a sample application directly on the Z-Stack you have many ways of setting Tx power, so try the most basic way first:

/********************************************************************************************************
 * @fn      ZMacSetTransmitPower
 *
 * @brief   Set the transmitter power according to the level setting param.
 *
 * @param   Valid power level setting as defined in ZMAC.h.
 *
 * @return  ZMacSuccess if PHY_TRANSMIT_POWER found or ZMacUnsupportedAttribute.
 ********************************************************************************************************/
uint8 ZMacSetTransmitPower( ZMacTransmitPower_t level )

0 dBm is default

Wrong - as is the case many times, the easy way is not the correct way to do something. Directly modifying the TXPOWER register does not register this desired tx power with the Z-Stack library and unexpected changing back to the default 0 dBm can occur. There is no global configuration setting to change to change the default tx power - the application code must add a call to ZMacSetTransmitPower() with the desired tx power.