Altera Cyclone II DSP Development Board Manuale Utente Scaricare il pdf (Pagina 68)

2–60 Reference Manual Altera Corporation

Cyclone II DSP Development Board August 2006

Clock Circuitry

Setting the Clocks

The clocks are selected from one of the following clock sources (as shown

in Figure 2–21):

■ The on-board clock oscillator (U20)

■ The custom clock oscillator (J20)

■ The SMA connector (J17)

The following two jumpers select the clock outputs from the clock buffer

(U16). (see Table 2–31):

1. J18 selects U20 or J20 as the selected clock oscillator to be input to

U16.

2. J19 determines which input to U16 (the selected clock oscillator or

the SMA clock), will be used to output the clocks.

Figure 2–22 shows U20, the on-board 100 MHz clock oscillator (it is

mounted in the gray area as the arrow indicates. If a custom clock

oscillator is used, it is installed on the blue socket (J20), as the arrow

indicates, on top of U20. Figure 2–22 also shows J18 and J19.

Figure 2–22. U20/J20, J18 & J19

J19

U20 - On-Board

100 MHz Oscillator

J18

Socket to Mount J20 - Custom Oscillato

(

Mounts on Top of U20

)

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Altera Cyclone II DSP Development Board Manuale Utente Pagina 68