i generate sine wave using micro controller dac mcp4921 but i want change peak value according analog value so please help me

 

Do you mean that you want to multiply the sine wave by the value of a control voltage?

If so, you can apply the control voltage to the REF input.

 

My guess.
They want to attach a pot to ADC and use it to control the amplitude of the sine wave coming out of DAC. I assume the uC has ADC. OP already told us that it does have DAC.

Also, increase button and decrease button can be used instead of pot+ADC combo.

 

Why no

My guess.
They want to attach a pot to ADC and use it to control the amplitude of the sine wave coming out of DAC. I assume the uC has ADC. OP already told us that it does have DAC.

Also, increase button and decrease button can be used instead of pot+ADC combo.

Why not then put the pot on the output of DAC.

 

Hi,

Yes there are actually many ways to do this.

Pot on input, pushbuttons on input, program control, pot on reference, pot on output, etc.

The key factor is whether it is done digitally or analog.

Analog input would be a pot or control voltage, either on an ADC input or on the REF input.

Digital input would be either rotary encoder or pushbuttons. There could be one up and one down button or a keypad to set the voltage level.

For the output, if there is a pot on the output or on the ref pin then that is analog output control.
If the DAC input codes are changed then that is digital output control.

So there are a lot of variations here depending on what the final goal is for the product.

 

Why no

Why not then put the pot on the output of DAC.

While a valid concept, it introduces additional components (interference) into the desired signal. If the quality of the desired signal is not too critical, then putting pot at the output is perfectly valid way to do it.

 

Keep in mind that we really don't know for sure what the TS wants to do.