Does an FPGA need an external clock source?

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vphaniendra

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does a FPGA need external clock input like 50MHZ and all....

I am using for implementing a USART in ALTERA STRATIX...where my data is synch clock coming from outside..i want to use it for all my internal devices.

Should I put a clock source also to the PLL dedicated clock inputs?? is it necessary..
 

Well...
FPGA itself has an internal clock. For USART you just need to divide it to your favorite baudrate.
 

moottii said:
Well...
FPGA itself has an internal clock. For USART you just need to divide it to your favorite baudrate.
Click to expand...

FPGAs have no internal clock sources. You need to connect an external source for anything to work synchronously.
 

Oh...yes. You're right.
I thought hi is talking about FPGA with its board.

- - - Updated - - -

By "internal" I meant the board clock ... :|
 

well dear!

the FPGA generally doesnot need clock source for combinational logic. The need of clock is application specific e.g sequential logic etc.

USART will be needing the sync pulse (either generated by PLL or board clock)..



Regards
 

Terrible idea, but you CAN actually generate an internal clock by creating a ring oscillator. But I wouldn't advise it.
 

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