This instructable shows you how to:
1. Program Arduino Pro Mini (ATMega328P) with Arduino Uno Board without removing the ATMega chip
2. Generate a pure sine wave with fixed frequency and minimal components.
Disclaimer: Code used is not made by me. The author is mentioned in the sketch.
Arduino boards used are clones. (Yeah, i know... I should donate).
Step 1: Upload Sketch to MiniPro With Arduino UNO Board
For uploading the sketch:
>Create a folder named "Waveforms" in ..."\Arduino\libraries\" and copy the heather attached named sinewavedata.h (default path "C:\Program Files (x86)\Arduino\libraries\Waveforms");
> Download the sketch and open.To change frequency, observe line "#define SAMPLE_RATE";
>Change device to Pro Mini from Tools > Board: > "Arduino Pro or Pro Mini" (or you can upload sketch to UNO as usual);
>Connect pin-to-pin RX, TX, Vdd=5V and GND from Arduino UNO board to ProMini board (as in image);
>Hold reset button on ProMini pressed and hit Upload;
>When status says: " Uploading..." release the reset, then you should have "Done uploading."
Now, your Pro Mini should generate a wave on pin 6 ( example in capture attached is 50Hz).
Step 2: Filtering Sinewave
To filter the sinewave you need a low-pass filter.
For 50Hz, I used a 470uH inductance and a 2.2uF capacitor (see schematic in image attached).
Supply 5V to Vdd pin, connect GND and it's done. Now you have a sinewave generator.