| ??? 04/13/06 15:02 Modified: 04/13/06 15:20 Read: times |
#114216 - Re: clock division... Responding to: ???'s previous message |
I always thought that the xtal signal is first divided by 2 and then fed to internal ckt as it was told to me by one of my friend when i was learning the basics of microcntroller Yes, that does apply to the classic 8051! The following link: http://www.intel.com/design/mc...270419.htm If you look at page-5 in the datasheet pdf, under the heading 'oscillator characteristics', you will find the following quote: "There are no requirements on the duty cycle of the external clock signal, because the input to the internal clock circuitry is through a divide-by-two flip-flop." That said however, Russell is correct about the resultant instruction timing, note the following example: On a 'classic' 8051 with a 12MHz crystal: 12MHz / 2 (after squaring Flip-Flop) = 6 MHz or 166.67ns per 'machine state' 6MHz / 6 Machine states = 1MHz (maximum)1-byte instruction rate. I suggest you read the "MCS-51 user manual" for more detailed info on the hardware: http://www.intel.com/design/mc...272383.htm VA |
| Topic | Author | Date |
| Capacitor significance | 01/01/70 00:00 | |
| Search | 01/01/70 00:00 | |
| Why burden caps must not be omitted | 01/01/70 00:00 | |
| Thanks: But still some more | 01/01/70 00:00 | |
| because that is when the address need be | 01/01/70 00:00 | |
| Divide dy 2 | 01/01/70 00:00 | |
| Where is this divide by 2? | 01/01/70 00:00 | |
| Thank you SIR | 01/01/70 00:00 | |
| Beware of applying specifics in general! | 01/01/70 00:00 | |
| Re: clock division... | 01/01/70 00:00 | |
| I suggest you do not | 01/01/70 00:00 | |
| Misleading information | 01/01/70 00:00 | |
| Divide-by-12 = Divide-by-(2*6) | 01/01/70 00:00 | |
| Oops - 1us, not 1ms!! | 01/01/70 00:00 | |
| not exactly ... | 01/01/70 00:00 | |
| it would not be so simple | 01/01/70 00:00 | |
| Clock division - in summary | 01/01/70 00:00 | |
| Re: Clk division summary | 01/01/70 00:00 | |
| Language? | 01/01/70 00:00 | |
| ok ok one more help | 01/01/70 00:00 | |
Links | 01/01/70 00:00 |