| ??? 06/13/07 08:58 Modified: 06/13/07 09:00 Read: times |
#140650 - Consider what you\'re doing. Responding to: ???'s previous message |
Purushottam Dayama said:
See this post:
http://www.8052.com/forum/read.phtml?id=140494 So you can put a gate like AC and get same clock as crystal from X2 pin. A few days ago, you didn't believe that. What changed your mind? I suppose that only clock reqd and not synchronous data.
That can be done with those uCs with about 100Mhz clock and
single instruction cycle. NONSENSE! The fast MCU will produce a 10 MHz clock only if you do something explicit to force it to do so. With only 10 instruction cycles per 100 ns output clock cycle, it can't really do much else. Would you consume nearly all the bandwidth of your MCU just to produce that one clock? If you take the crystal oscillator output and buffer it through an HC or AC gate, it will readily provide a clock at the frequency of the oscillator. If that happens to be 10 MHz, then so be it. A 10 MHz clock is rather slow on most MCU's of this genre. If the oscillator frequency is, say, 20 MHz, then an external divide-by-two would certainly do the trick. RE |
