S1B and S1A both set to on ON can lead to a race condition. When Bitgen option "reset_on_error" is not set, the module does not boot.
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1. If you don't use our USB API, switch S1A to OFF (S1B to ON). This way you disable FX2 activity on SPI bus and FPGA will boot from SPI by power on. (Fastest boot)
2. If you need USB API. -
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Init and boot time depend on board capacitance and power supply so may vary from board to board, which affect to boot behavior.
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