11 September 2015 Improvement of FPGA control via high speed but high latency interfaces
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Proceedings Volume 9662, Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2015; 96623G (2015) https://doi.org/10.1117/12.2205441
Event: XXXVI Symposium on Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments (Wilga 2015), 2015, Wilga, Poland
Abstract
In last years, the throughput of interfaces used in computer systems to control extension boards or external hardware has increased significantly. Unfortunately, those interfaces have also significant round-trip latency. This fact seriously impairs the efficiency of those control algorithms, which require a tight handshake. In such algorithms, the communication consists of a sequence of write and read operations, where read result (the handshake status) must be checked before the next write command is issued. This problem can be solved by the implementation of an intelligent controller in the controlled hardware. This controller should execute high-level commands locally performing all necessary handshake operations. Unfortunately, such a complex and highly specialized controller would consume a significant amount of FPGA resources. This paper presents an alternative approach which uses a highly simplified versatile controller implemented in FPGA. This simple controller may improve the efficiency of certain, relatively broad class of control algorithms. The proposed controller accepts a set of simple commands, which describe the write operations, read operations, and simple test operations. The control algorithm is described as a sequence of those operations. If the controlled hardware works correctly, all tests are passed, and the controller only notifies the host about successful completion. In case if certain handshake test fails, the host is notified about the position of the failed test and type of failure. That allows the controlling software to investigate and cure the problem. The controller may be also used in a standard mode, where status or result of each command is returned immediately and may be checked before the next command is issued.

The paper also proposes a simple method for writing of software, which uses the new controller. This method allows to implement the control procedures that are very similar to those using traditional controllers. That minimizes the effort needed to use the new controller and reduces a risk of errors.
© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Wojciech M. Zabołotny, Wojciech M. Zabołotny, } "Improvement of FPGA control via high speed but high latency interfaces", Proc. SPIE 9662, Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2015, 96623G (11 September 2015); doi: 10.1117/12.2205441; https://doi.org/10.1117/12.2205441
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