Course-Grained Reconfigurable Devices

2 Dataflow Machines General Structure:  ALU-computing elements,  Programmable interconnections,  I/O components. Most dominating coarse-grained systems:  PACT XPP  NEC-DRP  PicoChip  Morphosys  [RaPiD]  Chameleon

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4 PACT XPP V. Baumgarte, G. Ehlers, F. May, A. Nueckel, M. Vorbach, and M. Weinhardt, “PACT XPP A self-reconfigurable data processing architecture,” J. Supercomput., vol. 26, no. 2, pp. 167–184, M. Petrov, T. Murgan, F. May, M. Vorbach, P. Zipf, and M. Glesner, “The XPP architecture and its co-simulation within the simulink environment.” in Proceedings of International Conference on Field-Programmable Logic and Applications (FPL), ser. Lecture Notes in Computer Science (LNCS), vol Antwep, Belgium: Springer, Aug. 2004, pp. 761–770.

5 PACT XPP Aim:  Efficiently compute streams of data provided from different sources (e.g. A/D converters) rather than single instructions (as in Von-Neumann computers). Characteristic:  Computation should be done while data are streaming through the processing elements  it is suitable to configure the PEs to adapt to the natural computation paradigm of a given application.

6 Course Grain Architectures

7 PACT XPP: Architecture XPP (Extreme Processing Platform)  A hierarchical structure consisting of PAEs PAEs  Course grain PEs  Adaptive  Clustered in PACs  PA = PAC + CM  A hierarchical configuration tree  Memory elements (aside PAs)  I/O elements (on each side of the chip) PA

8 PACT XPP Architecture: CM CM (Configuration Manager):  Powerful run-time reconfiguration: −Configuration control is distributed over several CMs −PAEs can be configured rapidly in parallel while neighboring PAEs are processing data.  Entire applications can be configured and run independently on different parts of the array.  Reconfiguration can be triggered: −externally or − internally (by special event signals originating within the array −  self-reconfiguring Local CM:  One configuration manager (CM) attached to a local memory is responsible for writing configuration onto a PA.  The CMs at a lower level are controlled by a CM at the next higher level. Root CM:  Attached to an external configuration memory.  Supervises the whole device configuration.

9 XPP Architecture Scalability:  Can cascade multiple devices in a multi-chip module  Root CMs act like ordinary, subordinate CMs CM:  consists of a state machine +  internal RAM for configuration caching

10 PACT XPP Architecture: PAE 1.ALU PAE has: 1.ALU: is configured to perform basic operations: −Common fixed-point arithmetical and logical operations −Special three-input opcodes (e.g. multiply-add, sort, counters) −Generate events (e.g. counting termination, ovf, …) 2.Back Register: provides routing channels for data and events from bottom to top 3.Forward Register: provides routing channels from top to bottom

11 PACT XPP Architecture: PAE  Dataflow-Registers: used at the object output for data buffering in case of a pipeline stall.  Input Registers : can be pre-loaded by configuration data and always provide single cycle stall.

12 PACT XPP Architecture: PAE 2.RAM PAE:  As ALU PAE but instead of ALU, it has a dual port RAM  Useful for data storage (intermediate results) −Can be used in FIFO or RAM mode  Useful for LUT-based functions  The RAM generates a data packet after an address was received at the input.  Writing to the RAM requires two data packets: 1.for the address 2.for the data to be written. RAM

13 PACT XPP Architecture: Communication PAE Objects communicate via a packet-oriented network:  Two types of packets: −Data packets: uniform bit width for a device (specific to the device type, e.g 32) −Event packets: one or a few bits wide  Self-synchronizing: −An operation is performed as soon as all necessary data input packets are available. −The results are forwarded as soon as they are available, provided the previous results have been consumed. −  Thus possible to map a DFG directly to ALU objects, and to pipeline input data streams through it.  Event signals: −can trigger a self-reconfiguration −Can control the merging of data-streams

14 PACT XPP: Routing Routing and Communication:  Two independent networks: 1.for data transmission 2.for event transmission

15 PACT XPP: Routing 1.Horizontal Channel to connect a PAE within a row. 2.Vertical Channel to connect objects to a given horizontal bus. 3.Configuration Bus Horizontal routing channels Vertical routing channels

16 PACT XPP: Interface  Number and type of interfaces vary from device to device XPP42-A1: 6 internal interfaces consisting of:  4 identical general purpose I/O on- chip interfaces (bottom left, upper left, upper right, and bottom right)  One configuration manager (not shown on the picture)  One JTAG (Join Test Action Group, "IEEE Standard ") Boundary scan interface or for testing purpose Interfaces

The PACT XPP - Interface  The I/O interfaces can operate independent from each other. Two operation modes  The RAM mode  The streaming mode RAM mode :  Each port can access external Static RAM (SRAM).  Control signals for the SRAM transaction are available.  No additional logic required

The PACT XPP - Interface Streaming mode:  For high speed streaming of data to and from the device  Each I/O element provides two bidirectional ports for data streaming  Handshake signals are used for synchronization of data packets to external port