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The SPI bus can be used during configuration and operation in a plurality of ways as summarized respectively in Table 9 and Table 10. Any other usage of the SPI bus is neither supported nor recommended.

SPI bus for configuration

The SPI bus is used for configuration in two ways by default:

1. EZ-USB â-º Flashthe USB FX2 microcontroller (master) writes the PROM file (containing the FPGA configuration bitstream) to the SPI serial Flash memory (slave)
2. FPGA â—„ Flashthe FPGA (master) configures itself in Master SPI mode from the SPI serial Flash memory (slave).

In case (a), the FPGA shall be turned off to release its shared SPI pins.
In case (b), the USB FX2 microcontroller shall three-state (Z = high impedance) its shared SPI pins.

Table 9: SPI bus modes for configuration.
The PROM file (containing the FPGA configuration bitstream) can be written to the SPI serial Flash memory (slave) also through the SPI pins of B2B connector JM5 (attached device set to master mode). In this case, the FPGA shall be turned off or three-stated to release its shared SPI pins and the USB FX2 microcontroller shall three-state (Z = high impedance) its shared SPI pins.