LGT8F328P DAC example

/*
    LGT8F328P DAC example

    Generates a slightly complex analog signal.

    First, it generates a full ramp pulse then a sine
    wave, a half ramp, and last a small square. All at
    a fairly low frequency (1.8khz and less) but they
    are generated at different rates making it a little
    harder to trigger on with a scope.

    A good way to test the hold-off on your scope :)

    Scott Beasley (2021) No Copyright.
*/

#include <Arduino.h>
#include <avr/power.h>

#define SAMPLES 33

// Sine wave sample voltages
byte table[SAMPLES] = {
    0x80, 0x98, 0xb0, 0xc6, 0xda, 0xea, 0xf5, 0xfd, 0xff,
    0xfd, 0xf5, 0xea, 0xda, 0xc6, 0xb0, 0x98, 0x80, 0x67,
    0x4f, 0x39, 0x25, 0x15, 0x0a, 0x02, 0x00, 0x02, 0x0a,
    0x15, 0x25, 0x39, 0x4f, 0x67, 0x80
};

void setup ( )
{
    clock_prescale_set (clock_div_1); // Run at 32Mhz!

    analogReference (INTERNAL2V56); // 2.56v ref
    pinMode (4, ANALOG); // Set Pin 4 for DAC use.

    DAL0 = 0; // Set the DAC pin to 0v
}

void loop ( )
{
    // Keep this out of the "Arduino" flow for
    // smoother wave generation.
    // Remove the while if you need the serial monitor.
    while (1) {
        // Ramp up
        for (byte i = 0; i < 255; i++) {
            DAL0 = i;
            delayMicroseconds (5);
        }

        // Ramp down
        for (byte i = 255; i > 0; i--) {
            DAL0 = i;
            delayMicroseconds (5);
        }

        // Sine wave first
        for (byte i = 0; i < SAMPLES - 8; i++) {
            DAL0 = table[i]; // Write out value to the dac
            delayMicroseconds (15);
        }

        // Ramp up
        for (byte i = 0; i < 128; i++) {
            DAL0 = i;
            delayMicroseconds (5);
        }

        // Ramp down
        for (byte i = 128; i > 0; i--) {
            DAL0 = i;
            delayMicroseconds (5);
        }

        DAL0 = 190;
        delayMicroseconds (450);
        DAL0 = 0;
    }
}