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i have a joke problem,

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alitex

New Member
hi
i have a joke problem,
i use atmega16 controller in receive uart protocol from sm8223(The SM8223A is a FSK (Frequency shift keying) decoder and DTMF (Dual tone multi-frequency) receiver IC.)
when i set vcc=5V it didn't work (receive error dtmf),it really work at 5.7v only and receive correct dtmf,
any body know about this problem
thank u in advance
 

jimlovell777

New Member
I'm guessing values you've chosen for a particular part (resistor or capacitor) is off and when you raise the voltage the frequency also shifts. It just so happens to shift where you need it at 5.7V.
 

Boncuk

New Member
As far as I remember a UART is a serial device. Serial ports normally (standard) work at voltages of ±15V.

Using a MAX232 it offers an output voltage high enough using a charge pump to generate higher voltage than the usually applied VCC of 5V in logic circuits.

At 5.7V your circuit might still be critical under noisy conditions if you don't use a charge pump device. It outputs at least ±12V.

Boncuk
 

Hamyrenz

New Member
I think the atmega16 controller has requirement voltage in order to regulate. Just based on my opinion, I don't really encounter this problem. Hope you will get a solution for your problem.


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