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AD5627 Dual Channel I2C DAC Driver

 
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AD5627 Dual Channel I2C DAC Driver
PostPosted: Mon Jan 10, 2022 3:12 am     Reply with quote

Tested AD5627 Dual Channel I2C DAC Driver

Code:
/*
      AD5627 I2C DAC Driver

      AD5627R/AD5647R/AD5667R, AD5627/AD5667
      Tested on AD5627BCPZ-REEL7

      Dual channel I2C DAC
*/

/*
    Pin connections:
    ADDR   -> GND
    LDAC   -> GND
    EP     -> GND
    CLR    -> VDD
    VREFIN -> VDD

    In this case VDD is 5V
*/

/*
    Address is 0x0F when ADDR->GND (datasheet)
    We shift-left the address by 1 bit
    LSB bit determines the operation is write or read R/W
    LSB = 0 is write
    LSB = 1 is read
    0x0F << 1 is 0x1E (write)
    0x0F << 1 | 0x01 is 0x1F (read)
*/
#define DAC_ADDRESS     0x1E // write address
#define DAC_REF_VOLTAGE 5000.0 // mV
#define DAC_RESOLUTION  4096.0 // 12 bits DAC

/*
    Hardware I2C selected
*/
#use i2c(MASTER, I2C1, FORCE_HW, NOINIT)

/*
    Commands
*/
#define DAC_A  0x18 // Command: DAC A one block write
#define DAC_B  0x19 // Command: DAC B one block write

/* All commands
#define _CA1   0x18; // Command: DAC A one block write
#define _CB1   0x19; // Command: DAC B one block write
#define _CA2   0x58; // Command: DAC A multiple block write
#define _CB2   0x59; // Command: DAC B multiple block write
#define _CA3   0x00; // Command: DAC A using LDAC to update.
#define _CB3   0x01; // Command: DAC B using LDAC to update.
*/

/*
    Initialize I2C
*/
#define DAC_init()  i2c_init(100000) // supports up to 400000

/*
    Voltage set on channel in millivolts

    param ch : command, used as channel DAC_A or DAC_B
    param v  : voltage in millivolts, 0...5000 mV
    returns false on error
*/
bool DAC_set(int8 ch, int16 v)
{
    int8 ack; // 0: ack - else nack or collusion
    int16 out;
    int8 H, L;

    out = (int16)((float)v * DAC_RESOLUTION / DAC_REF_VOLTAGE);

    if(out > 4095) // limit the value to 12 bits
    {
        out = 4095;
    }

    /*
     4095 -> 0xFFF is maximum value where generates 5000.0 mV on DAC output
     When sending 0xFFF over I2C;
       H holds the 0xFF (whole byte)
       L holds the 0xF left aligned (a nibble)
     so L holds left aligned 4 bits only
     */
    H = out >> 4;
    L = (out << 4) & 0xF0;

    i2c_start();
    ack = i2c_write(DAC_ADDRESS); // Device address
    if(0 == ack) // check ack to send data to avoid errors
    {
        i2c_write(ch); // CMD
        i2c_write(H);
        i2c_write(L);
    }
    i2c_stop();

    return 0 == ack;
}

/*
    Sawtooth signal generation test on both channels
*/
void DAC_test() // Call this function in a loop
{
    static int16 q = 0; // [mV]

    q++;
    if(q > 5000) // [mV]
        q = 0;
    DAC_set(DAC_A, q);
    DAC_set(DAC_B, q);
}

/*
    Pseudo main function
*/
void main()
{
    DAC_init();

    for(;;)
    {
        DAC_test();
    }
}
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