sINE WAVE GENERATION USING DAC AND ATMEGA MCU

[DK BOSS]

I want to generate pure sine wave using a good and cheap dac coupled with atmega.
Kindly Someone through some light over .....

 

[jayanth.devarayanadurga]

Use I2C or SPI DACs from LTC or ADI. They are very good. How may bit DAC you want to use?

 

[doraemon]

Hello!

I would further ask:
- What do you mean by "pure" sine wave? What is your max harmonic distortion?
- What do you mean by good? (how good?, what noise ratio, etc...)
- What do you mean by cheap? Depending on the application, 1 Euro can be expensive and 100 Euros can be cheap.

Dora.

 

[DK BOSS]

About 1~3 Euro max
Pure sine wave means that the thd should be less then 1%
Noise ratio should be withing a acceptable range
Actually I want to build a Descent Sinewave Inverter for my house.

Prefered Communication SPI/I2C

 

[doraemon]

Hello!

I will assume that your "acceptable" noise ratio is in the same range (less than 1%) as the THD.
-> On one 2ms period, around 0 V, you will have your max quantization noise. Choose the
sampling period small enough so that this noise fits your needs. Be careful with your SPI
requirement: if you find out that your sampling frequency should be, say, 2000 steps per period,
then you have to output samples at 1 MHZ. Then, since 1 sample will require at least 8~10 bits
depending on the converter, plus some possible heading data, then you will end up with a SPI
frequency around 10 MHz. One more thing: if you use a converter with a resolution greater
then 8 bits, then you will likely need to send 2 bytes per sample, which will double your SPI
frequency. Not all microcontrollers are capable of sending SPI data at 20 MHz. Check with ATMEGA.

Dora.

 

[kripacharya]

Here is an ultra simple, high accuracy (for the price & simplicity) DDS you can make very cheaply. For a fixed frequency you can eliminate the rs-232 & other interfaces, even eliminate the crystal, and have just the uC plus 9 resistors to do the job. Some code changes will be required, but that should be easy.

**broken link removed**