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Si5338 programmable clock generator chip is used to generate clocks with 25 MHz oscillator as input connected to the pin IN3. There is a I2C bus connected between the FPGA bank 14 (master) and clock generator chip (slave) which can be used to program output frequencies. See the reference design for more information.

On-board Peripherals

32 MByte Quad SPI Flash Memory

On-board QSPI flash memory S25FL256S (U14) is used to store initial FPGA configuration. Besides FPGA configuration, remaining free flash memory can be used for user application and data storage. All four SPI data lines are connected to the FPGA allowing x1, x2 or x4 data bus widths. Maximum data rate depends on the selected bus width and clock frequency used.


SPI Flash QE (Quad Enable) bit must be set to high or FPGA is unable to load its configuration from flash during power-on. By default this bit is set to high at the manufacturing plant.

System Controller CPLD

System Controller CPLD (Lattice MachXO2-256HC, U3) is used to control FPGA configuration process. The FPGA is held in reset (by driving the PROG_B signal low) until all power supplies have stabilized.


  • Part number: IM4G16D3FABG-125I
  • Supply voltage: 1.5V35V
  • Organization: 32M words x 16 bits x 8 banks
  • Memory speed: limited by Xilinx Artix-7 speed grade and MIG