Datasheet

Genesys 2 FPGA Board Reference Manual

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4 Fan

The Genesys 2 comes with a fan and a secondary heat sink pre-installed on the FPGA package heat sink. The fan is

powered from the external 12V DC supply rail and controlled by the FPGA. Control is done by the “FAN_EN” signal.

Pulling the signal high from the FPGA opens the transistor driving the fan. This pin is pulled high by default.

Feedback is obtained on the “FAN_TACH” signal. This generates a pulse with a frequency proportional to the

rotation speed of the fan. Each rotation generates four pulses on “FAN_TACH”. The period of these pulses shortens

with higher rotation speed and lengthens at slower speeds.

1 rotation

3.3

1 pulse

Fan locked

Figure 4. “FAN_TACH” fan speed feedback signal.

The fan uses a 3-pin header for power, ground and feedback. It is recommended leaving the fan connected at all

times. Depending on FPGA design complexity and actual usage the fan might not be needed at all. In this case the

enable signal can be used to stop the fan, and start it when the FPGA internal temperature (as read by the XADC)

gets above a certain limit.

5 FPGA Configuration

After power-on, the Kintex-7 FPGA must be configured (or programmed) before it can perform any functions. You

can configure the FPGA in one of four ways:

1. A PC can use the Digilent USB-JTAG circuitry (port J17, labeled “USB JTAG”) to program the FPGA any time

the power is on.

2. A file stored in the nonvolatile serial (SPI) flash device can be transferred to the FPGA.

3. A programming file can be transferred to the FPGA from a micro SD card.

4. A programming file can be transferred from a USB mass-storage device (ex. pen drive) attached to the

USB HOST port.

Figure 5 shows the different options available for configuring the FPGA. An on-board “mode” jumper (JP5) and a

media selection jumper (JP4) select between the programming modes.