system
March 21, 2014, 2:39pm
1
Hi all,
I am trying to hook up the Texas Instruments DAC-5574 to a Nano using the Wire library.
I'm having some problems extracting exactly what I need to send via I2C to set the analog values on each of the 4 outputs.
In Setup I have the normal:
Wire.begin();
To set the output level on port A to 5v (0xff), I am using:
Wire.beginTransmission(0b1001100); // A0 & A1 are both tied to ground
Wire.write(byte(0b00000010)); //
Wire.write(byte(0xff)); //
Wire.write(byte(0xff)); //
Wire.endTransmission();
The only slight problem is - it does nothing!
I am guessing I have totally misinterpreted the datasheet but I cannot find any code examples anywhere
I'll keep trying but if anyone has any suggestions, they would be very much appreciated.
Many thanks,
James
system
March 21, 2014, 5:16pm
2
You interpreted the datasheet correct.
Let's go back one step.http://playground.arduino.cc/Main/I2cScanner
system
March 24, 2014, 9:05am
3
Hi,
Sorry for the delay - I left my Arduino hardware at the office over the weekend!!!
I have run the Scanner and I get this: (I've added labels for the items I am aware of)
I2C device found at address 0x27 ! LCD
I2C device found at address 0x48 !
I2C device found at address 0x4C !
I2C device found at address 0x50 ! EEPROM
I2C device found at address 0x51 !
I2C device found at address 0x60 ! TLC-59116
I2C device found at address 0x68 ! Realtime Clock
I2C device found at address 0x6B !
I'm not sure what the other four are but I hope one of them is my DAC!
system
March 24, 2014, 9:15am
4
As I have A0 and A1 tied to ground, the device address should be 0x4C
system
March 24, 2014, 9:48am
5
This is your DAC: http://www.ti.com/product/dac5574
Is it possible to remove the other I2C devices ?
I have been looking at the datasheet, and I don't not fully understand it. I don't see a special power up sequence, so writing the control byte with msb and lsb should do it.http://e2e.ti.com/support/data_converters/precision_data_converters/f/73.aspx
system
March 24, 2014, 9:57am
6
Excellent!!!!
Looks like I was sending the wrong value for the control byte!
#include <Wire.h>
// Define I2C Device Addresses
#define kDACAddress1 0x4c // Assumes A0 to A1 are connected to ground
// the setup routine runs once when you press reset:
void setup()
{
// Serial Port Initialisation
Serial.begin(9600); // Output to the Serial Monitor
delay(500); //
// Initialise the I2C Library
Wire.begin();
}
// Loop
void loop()
{
i2c_dac5574_setvalue(kDACAddress1, 0, 0x00);
delay(2000);
i2c_dac5574_setvalue(kDACAddress1, 0, 0x80);
delay(2000);
i2c_dac5574_setvalue(kDACAddress1, 0, 0xff);
delay(2000);
}
// i2c_dac5574_setvalue (Sets the Value of the selected DAC Output)
// - Parameter 1 : Device Address
// - Parameter 2 : Output A-D 0x00 to 0x03
// - Parameter 3 : Value 0x00 to 0xff (0 - 5v)
// Control Byte 0 0 L1 L0 x A1 A0 0 | Chan
// 0 0 0 1 0 0 0 0 | A
// 0 0 0 1 0 0 1 0 | B
// 0 0 0 1 0 1 0 0 | C
// 0 0 0 1 0 1 1 0 | D
void i2c_dac5574_setvalue(byte DACAddress, int output, int value)
{
Wire.beginTransmission(DACAddress);
byte ctrl = 0x00;
ctrl |= 0x10; // L0=1
switch (output)
{
case 0: // A1=0, A0=0
break;
case 1: // A1=0, A0=1
ctrl |= 0x02;
break;
case 2: // A1=1, A0=0
ctrl |= 0x04;
break;
case 3: // A1=1, A0=1;
ctrl |= 0x02;
ctrl |= 0x04;
break;
}
Wire.write(byte(ctrl)); // port a with next value
Wire.write(byte(value)); // MSB
Wire.write(byte(value)); // LSB
Wire.endTransmission();
}
system
March 24, 2014, 10:38am
7
The function is working great now for all 4 outputs
system
March 24, 2014, 12:48pm
8
Very Nice.
