Development of a USB camera using a general purpose microcontroller

Abstract: The aim for this project has been to develop a low cost USB camera, that uses a general purpose microcontroller to control the image sensor. The camera is intended to be used in a general purpose development platform at Optronic AB. The development platform is designed to be used in many various projects and thus the camera also has to be as flexible as possible. The origin of the project is an existing product that needed improvements. The predecessor of this camera employed a Complex Programmable Logic Device (CPLD) to generate the control signals to the image sensor, an IBIS5-B-1300from Cypress semiconductor. In this design, an EZ-USB FX2LP microcontroller, also from Cypress semiconductor, will be responsible for generating the necessary control signals for the image sensor. The microcontroller was chosen mainly because it is a high-speed USB microcontroller and that it has a General Programmable Interface (GPIF). The GPIF excludes the need for anyadditional logic that interfaces the microcontroller to the image sensor. This reduces the total cost of the camera. The microcontroller also has up to four large endpoint First In - First Out (FIFO) queues. The endpoint FIFOs and the GPIF makes the microcontroller suitable for controlling peripheral devices and handling high speed data transfers. The GPIF of the EZ-USB FX2LP microcontroller has never been used to control this kind of image sensor before and therefore the aim of the project is also to examine if the microcontroller is up for the task. In case of success the construction will become more cost effective than its predecessor. The switch from CPLD to microcontroller should not have an impact on the quality of the images produced, but will reduce the cost and increase the flexibility of the system. Even though only one main component is replaced it is necessary to develop a completely new design, for both hardware and software. Mainly in software since code for a CPLD is written in hardwaredescription language such as VHDL or Verilog, and the code for amicrocontroller is written in C. But also the hardware is an entirely newdesign using only small blocks such as power supply from the old design.The work done and considerations made during development of thiscamera is treated in detail in this report.To facilitate this work a development kit from Cypress semiconductorhave been used (CY3684). The kit includes a development board thatemploys the EZ-USB FX2LP microcontroller and a software developmentenvironment including example code.