Nowadays, Internet of Things (IoT) devices are widely deployed and how to power such massive IoT devices has become a significant challenge. Especially for the battery-powered IoT devices, limited energy storage and continuous energy consumption result in frequent battery replacement and potential environmental pollution. Because radio frequency (RF) signals carry not only information but also energy, Wireless Power Transfer (WPT) in RF domain has been proved to be a reliable and controllable technology to deal with this problem. A typical Data and Energy Integrated Network (DEIN) commonly conceives one DEIN base station and numerable DEIN devices. The DEIN base station is capable of transmitting data and energy integrated signals to the DEIN devices with Simultaneous Wireless Information and Power Transfer (SWIPT) technology, and the DEIN devices are capable of harvesting energy from the downlink RF signals for uplink data transmission. In order to coordinate the wireless data and energy transmission and avoid conflicts, a transmission protocol based on the Time-Division Multiple Access (TDMA) scheme is designed. Furthermore, an optimization problem of minimizing the energy consumption of the DEIN base station is formulated. In order to address this problem, this paper proposes an energy-efficient algorithm by jointly optimizing of the transmission power of the DEIN base station, the uplink and downlink time slots and power splitting factors of the IoT devices. Both the effectiveness and efficiency of the proposed joint optimization algorithm have been validated with the simulation.