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How to convert a crystal with 12Mhz to 11.0592 frequency?

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mohannad100

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hi every body
our market doesnot have a crystal with a frequency 11.0592 ihave a crystal with 12Mhz can i convert 12Mhz to 11.0592 by some electornic circuit
can you tell me in which devices i can found 11.0592Mhz to remove it from the device and use it in my serial communication project using 8051 because i face abaud rate error and got nothing in serial port comm1 or comm2
 

why 11.0592 mhz is used

That requires a frequency divider with a ratio of 0.9216 !!! That is almost impossible to build or not practical. What you can do is use a 22.1184MHz crystal along with external square wave generator circuit and pass it through a D-Flip-Flop (wired as bi-stable) to divide it by 2 to get 11.0592MHz. Or since it is for baud rate generation, you might not even want to divide it by two, 22.1184 should work just fine. What microcontroller are you using ? 8051?

And if even 22.1184MHz is not available, you might want to consider changing your baud rate which is supported by 12MHz crystal. Bye the way what baud rate are you trying ?
 

generador clock 12mhz

11.0592MHz would be needed by a standard 8051 to generate baud rates above 38k. It can't be replaced by any simple circuit and 12 MHz crystal. A PLL (e. g. with a HC4046) would be the most simple solution.

Generally, a maximum deviation of ca. 2 % is acceptable for a UART baud generator. It can't be achieved reliablely with a simple RC oscillator. Some processors are using calibrated RC oscillators internally, but they utilize special temperature compensation techniques and are fighting hard to achieve the tolerances though.
 

why 8051 use 11.0592 instead of 12

thanks to all
 

what is 11.0592 baud

Additional, a fractional divider that is skipping 1 of 13 clock pulses would achieve the required frequency without a PLL. I expect, that a 8051 could operate with such an odd clock. 3 or 4 standard CMOS IC (a 4-bit binary counter, a flip-flop, decoding logic) would be necessary for the circuit.
 

12mhz, baud rate, mcs51

FvM said:
Additional, a fractional divider that is skipping 1 of 13 clock pulses would achieve the required frequency without a PLL. I expect, that a 8051 could operate with such an odd clock. 3 or 4 standard CMOS IC (a 4-bit binary counter, a flip-flop, decoding logic) would be necessary for the circuit.
Click to expand...
Can you explain your calculation? It might be really simple but I am not getting it :cry:
 

11.0592 mhz 12mhz

Pulse swallow method 12/13 will produce 11,0769MHz frequency from 12MHz. Question is if such signal is usable without filtering.
 

11.0592

Borber said:
Pulse swallow method 12/13 will produce 11,0769MHz frequency from 12MHz. Question is if such signal is usable without filtering.
Click to expand...
Apart from that will it generate required baud-rate as it is not exact 11.0592 ?
 

12 mhz crystal different from 11.0592

The best solution to mohannad100 problem is that somebody send this crystal to him in Iraq.
 

12Mhz to 11.0592

u right borber thank you but my problem is solved i get the crystal from jordon tody
thanks to all gentelmans that replay.
 

Re: 12Mhz to 11.0592

Very good. By the way. 24/13 MHZ is used as baud clock for many PC motherboards. It's accurate enough. Also fractional dividers are available with some uP, e. g. TI MSP 430 family. They show some jitter in output, but it's no problem for UART applications.
 

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