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Stanford µSequencer. December 2003. Motivation. Control, initialization, and constant maintenance of Avalon peripherals Perfectly deterministic Microprocessor is larger than necessary for these tasks Engineering a custom state machine increases time-to-market
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Stanford µSequencer December 2003
Motivation • Control, initialization, and constant maintenance of Avalon peripherals • Perfectly deterministic • Microprocessor is larger than necessary for these tasks • Engineering a custom state machine increases time-to-market • Avalon MicroSequencer provides a solution • Configurable, programmable state sequencer that fits into the Avalon bus fabric • Leverages all the benefits of SOPC Builder
Configuration Options • Size of the Instruction ROM • Words or K words • 36-bit Instruction words • Implemented in Stratix/Cyclone synchronous RAM blocks • Optional 32-bit accumulator register • For loop counting, memory indexing, etc.
Software Build Tab • Automated generation of memory files for Instruction ROM • .mif (Quartus compilation) • .dat (Verilog simulation) • .hex (VHDL simulation) • Files placed in system directory • Software can also be built by an external Perl script.
Sequencer Architecture (base configuration) OPCODE & DATA ROM COND_BIT IP == && +1 OP CODE DATA || Execution Controller DATA_REG Address RD Data WR Data DATA_REG - a 32-bit wide register IP - instruction pointer COND_BIT - condition code bit Avalon Master
Sequencer Architecture (with accumulator register) OPCODE & DATA ROM COND_BIT IP == && +1 OP CODE DATA || + CNT_REG Execution Controller DATA_REG Address RD Data WR Data DATA_REG - a 32-bit wide register IP - instruction pointer COND_BIT - condition code bit CNT_REG - 32-bit accumulator Avalon Master
Sequencer Instructions (base configuration) LD(data) - DATA_REG = data WR(addr) - Avalon Write *(addr) = DATA_REG RD(addr) - Avalon Read DATA_REG = *(addr) AND(data) - DATA_REG &= data OR(data) - DATA_REG |= data CMP(data) - (DATA_REG == data) ? (COND_BIT = 1) : (COND_BIT = 0) JMP(true_off, false_off) - ((COND_BIT) ? (IP=true_off) : (IP=false_off)) Note – these instructions are implemented as C macros, so the state machine definition is actually written in C, which means that you can leverage the C language to do very complex things if you are so motivated. Please see the example state machine definitions that are output in the components SDK for examples on how to use these instructions in an actual state machine.
Additional Instructions (supported when configured with accumulator register) LDC(data) - CNT_REG = data INC(data) - CNT_REG += data WRC() - Avalon Write *(CNT_REG) = DATA_REG RDC() - Avalon Read DATA_REG = *(CNT_REG) CMPC(data) - (CNT_REG == data) ? (COND_BIT = 1) : (COND_BIT = 0) CPC() - DATA_REG = CNT_REG Note – these instructions are implemented as C macros, so the state machine definition is actually written in C, which means that you can leverage the C language to do very complex things if you are so motivated. Please see the example state machine definitions that are output in the components SDK for examples on how to use these instructions in an actual state machine.
OPCODE/DATA Word Format 36-bit ROM Word OPCODE DATA 32-bit DATA 4-bit OPCODE
SOPC Builder system configuration/generation Software Development Software Compilationin SOPC Builder or using external script ModelSim Simulation Quartus Compilation Design Flow Quartus Smart Compile will skip the Analyzer and Fitter stages of compilation if only the MIF file has changed since the last full compile! (MIF file must be added to the project for this to work)
Performance • Approximately 130 LE’s • 270 with accumulator register • Using physical synthesis options in Quartus, we achieved fmax as high as 235 MHz on a Stratix 1S10 device, -5 speed grade • Configuration with accumulator runs at 200 MHz. • Executes nearly one instruction per cycle • Three exceptions: • One cycle delay before executing first instruction • One cycle delay after each jump (NOP inserted by compiler) • Avalon read/write instructions require sequencer to wait for transfer
Installation Package • InstallShield Package contains everything necessary to begin developing with the Avalon MicroSequencer • SOPC Builder component class, HDL generator, & sample SDK • GCC and associated Cygwin packages (for microcode builder) are added to the existing SOPC Builder installation of Cygwin • Avalon MicroSequencer Kit • Preliminary Datasheet • Four example/demonstration designs • Tutorial with detailed instructions, summary readme, and starter projects Note: The installation package should be used with Quartus II 4.0.
