This paper proposed a lens assisted two-dimensional beam scanning and ranging device based on the control of field programmable gate array (FPGA). A lidar system with 16 scanning angles, 19.5 m ranging distance, and 2 cm ranging error was achieved through the Mach-Zehnder interferometer (MZI) optical switches with a binary tree structure, FPGA control, and pulse width modulation (PWM). Our work shows the potential of efficient FPGA control in the lens assisted beam scanning technology. The control scheme selected in this paper only needs log N channels of PWM waveforms for N optical transmitting ports (N beam scanning angles). Compared with the typical optical phased array (OPA) technology that needs N channels of digital-to-analog converter (DAC) for N optical transmitting ports (the control complexity is O(N)), this scheme greatly reduces the control complexity (O(log N)) and system cost. Therefore, it is expected to pave the way towards the application of lidar systems based on integrated beam scanning technology.