michele
1ddaa9adfd
Yosys + nextpnr-ecp5 synthesis of the extended spi_neuron_top.v (layer_sequencer + mux + arbiter Port C wired in), speed grade -8, N_INPUTS=32/N_NEURONS=1: PARALLEL=8 -> 40.57 MHz FAIL, PARALLEL=2 -> 42.54 MHz FAIL. Both worse than Phase 4 alone (~52.58/~55.85 MHz for the identical configs) -- the Phase 5 wiring cost real timing headroom. Critical path also shifted from Phase 4's saturation- comparator finding to neuron_memory's x_mem/w_mem LUT-RAM read-mux tree feeding the accumulator. Full analysis and candidate next steps (block RAM for x_mem/w_mem, pipelining, a seed sweep to separate placement noise from a structural bottleneck) recorded under Phase 7 in docs/FPGA-NeuralNetwork-Engine.md.