基于Hi3515的自动聚焦系统

本文提出了一种基于海思公司Hi3515处理芯片的自动聚焦系统的整套设计方案。该系统使用COMS传感器向Hi3515传入YUV数字信号，Hi3515芯片根据该数字信号进行聚焦评价并且根据聚焦策略判断电机的步进方向，最后使用礟D16835芯片来推动聚焦电机，从而实现了自动聚焦。在聚焦评价算法上，采用了Reborts梯度算法并在其像素差值累加方面进行了改进。聚焦策略上对单调性判断法进行了改进，避免了局部极致的出现。在实验中以及应用中证明这个聚焦系统的聚焦效果可以满足实际的应用需求，已成功应用于视频展台产品中。

Auto-focusing System being based on Hi3515 platform

In this paper, we describe a whole plan of auto-focus system based on Hi3515 which designed by Hisilicom Technologies Co.,Ltd. The system uses CMOS sensor to transmit YUV digital signal into chip Hi3515. The Hi3515 chip do focusing evaluation on basis of the signal, and judge the step direction by focusing strategy, then promote the motor to focus. Focusing evaluation uses Reborts gradient algorithm, and improves its aspect of pixel difference accumulation. Focusing strategy use modified monotonic judgment which avoids the appearance of local extreme value. On experience and practical application, the system focusing effect can satisfy the need of application requirement, and has successfully been used in video presenter product.