PYNQ Overlays简介

The Xilinx® Zynq® All Programmable device is an SOC based on a dual-core ARM® Cortex®-A9 processor (referred to as the Processing System or PS), integrated with FPGA fabric (referred to as Programmable Logic or PL). The PS subsystem includes a number of dedicated peripherals (memory controllers, USB, Uart, IIC, SPI etc) and can be extended with additional hardware IP in a PL Overlay.

Overlays, or hardware libraries, are programmable/configurable FPGA designs that
extend the user application from the Processing System of the Zynq into the Programmable Logic. Overlays can be used to accelerate a software application, or to customize the hardware platform for a particular application.
Overlays是一个硬件库。是一个可编程的FPGA设计，为从PS里扩展到PL服务，这个库可以用来加速软件应用，或者自己定制overlay为特殊应用服务

For example, image processing is a typical application where the FPGAs can provide acceleration.== A software programmer can use an overlay in a similar way to a
一个软件编程者可以运用overlay在FPGA层面上像使用软件库一样进行一些图像处理
software library to run some of the image processing functions (e.g. edge detect,
的操作。overlay会动态把他们加载进FPGA里面进行运算加速。
thresholding etc.) on the FPGA fabric. Overlays can be loaded to the FPGA dynamically, as required, just like a software library.== In this example, separate image processing functions could be implemented in different overlays and loaded from Python on demand.

PYNQ provides a Python interface to allow overlays in the PL to be controlled from
PYNQ提供了一个python界面允许PL里面的overlays被PS里面运行的python控制
Python running in the PS. FPGA design is a specialized task which requires hardware engineering knowledge and expertise. PYNQ overlays are created by
pynq overlays是专人开发的，就是为了方便直接在软件层面做开发
hardware designers, and wrapped with this PYNQ Python API. Software developer
can then use the Python interface to program and control specialized hardware overlays without needing to design an overlay themselves. This is analogous to software libraries created by expert developers which are then used by many other software developers working at the application level.
（原文渣翻，只是自己看的，不足之处请谅解）