Design And Implementation Of Optical Multi-touch Screen Based On STM32and FPGA

As the development of the society and innovation of science and technology,more andmore people pay attention to man-machine interaction.Traditional device of man-machinesuch as mouse,keyboard and Single-point touch devices can’t meet the demands of users.Naturally,Multi-touch technology emerge as required.It developments rapidly based onSingle-point touch technology and makes the numbers of touch point more.Even differentpeople can operate Multi-touch devices at the same time.It makes the operation more flexibleand brings users unprecedented experience.This paper proposes a design method of Multi-touch based on STM32MCU.It includescoordinate operation of Multi-touch,HID device communication and FPGA implementation ofCORDIC algorithm used by coordinate operation.Following is the main content.Firstly,we select cheap CMOS as image acquisition device and locate the touch pointbased on the camera crossing location principle.Meanwhile,we deduce the formula ofcoordinate operation and perform the operation on STM32.Secondly,we study the principle of CORDIC algorithm,so that we can implement sinefunction and arc-tangent function on FPGA.In addition,we do the simulation experiment,sothat we can operate coordinate of touch points.Thirdly,design the USB interface circuit with STM32and study USB protocol of HIDclass device and Microsoft white paper,so that STM32can be simulated as touch device, itcan communicate with Windows7as HID class device.Thus,STM32can transmit the data oftouch points to the Windows,then Windows will respond correspondingly.This designing has low cost hardware,it has huge advantage in large size device,it is aconvenient plug-and-play device.so to some extent,it has practical value.