Reliable Data Storage using Reed Solomon Code Supervised by: Isaschar (Zigi) Walter Performed by: Ilan Rosenfeld, Moshe Karl Spring 2004 Midterm Presentation

Problem: Cosmic radiation in space causes bit-flips, and therefore valuable information could be lost. Solution: All data stored will first be encoded via a Reed Solomon Encoder. A Reed Solomon Decoder will be used when data retrieval is required.

Memec Design Virtex II Pro Development Kit Hardware Resources Xilinx Virtex II Pro RocketIO comm. ports

Software Tools HDL Designer ModelSim Embedded Development Kit

Basic Project Function Reed Solomon Encoder Reed Solomon Decoder Storage Device Hi res Hi freq. input data (possibly) corrupted data (hopefully) corrected data

System Block Diagram PLB Rocket I/O SDRAM Memory Controller PowerPC RS Decoder RS Encoder Storage Camera CPU offload unit

First Semester Goals In-depth acquaintance with the development environments Implementing the Reed Solomon cores as slaves on the bus

First Semester Goals – cont. PLB Memory Controller PowerPC RS Decoder RS Encoder SDRAM PLB2OPB Bridge OPB UART Hyperterminal on DIGLAB PC IPIF FIFO IPIF

First Semester Goals – cont. The PLB clock frequency is 100MHz If we perform an 8-bit write per clock cycle to one encoder we can expect a 0.8Gbps throughput out of the encoder. Higher throughput can be achieved by: –Writing more than 8-bits per cycle (which comes on the expense of encoder work freq) – Using multiple encoders in one IP block. If 32-bit words are to be encoded in the 100MHz frequency then we are limited by the Gbps per channel RocketIO rate.

IPIF The IPIF is (as its initials suggest) an interface between the bus and the IP. It takes care of the transaction protocols on the bus and simplifies access to the IP. It also enables special features such as S/W Resetting, User Logic address ranges, interrupts, Bursting, DMA support and more.

IPIF – continued

Bus Transactions Bursting enables us to transfer data with a higher throughput!

Reed Solomon cores When creating the cores using Xilinx CoreGen, the following parameters are needed: –k: number of symbols per data block (to be encoded) –n: total number of output symbols (original data + check symbols) –s: number of bits per symbol The Reed Solomon code can detect n-k symbol errors and correct (n-k)/2.

We have chosen k=239, n=255, s=8, which are similar to G. 709 standard. RS cores

RS Cores - Detailed

FIFO Between the encoder and the decoder we have put a Xilinx Synchronous FIFO. The FIFO also has an IPIF interface to the PLB connected to its outputs, in order to look at the intermediate data. For this we have chosen a 1024x8bit FIFO.

Original 1st Semester Schedule 4 weeks (done): study the development environments, the Virtex II Pro and PowerPC. Building a tutorial application using the CPU. 1 week: Study the Reed Solomon cores. 1 week: Study the PLB Bus. 2 weeks: Building a test application for connection to the bus. 6 weeks: Designing the described system, simulating, implementing and debugging.

1st Semester: Remaining Weeks We have already connected the FIFO and Encoder to the system. The following still needs to be done: 1 week: Testing the Encoder and FIFO 1 weeks: Connecting the Decoder 2 weeks: Testing the whole system. 3 weeks: Building a basic RocketIO application. Possible optimization of the system: Using more PLB data lines. Using multiple RS cores simultaneously. Using burst transactions on the bus.

Second Semester Goals Building a CPU offload unit that will be a master on the PLB, perhaps using the DMA capability of the IPIF. Using another development board to simulate a storage device. Performing fast and reliable data transfers between the two boards using the RocketIO ports.

Second Semester Goal Main System Diagram PLB Rocket I/O SDRAM Memory Controller PowerPC RS Decoder RS Encoder Second Development Board (simulating storage device) CPU offload unit PLB2OPB Bridge OPB UART, etc.

Second Semester Goal Storage Simulation Diagram PLB Rocket I/O MemoryPowerPC PLB2OPB Bridge OPB UART, etc. Main Development Board

Thank you