DAC8411 Testing

Hi Alexander,

Do you think you can provide us with some SPI captures on an oscilloscope? This will help us understand if the micro controller is outputting valid codes to the DAC.

Unfortunately we are not qualified to verify Arduino code. I would suggest implementing a simple SPI interface first, and then I can help you debug the issues that are specific with the DAC8411.

Hello,

I didnt see anything from the oscilloscope however I do have a logic analyzer output. Here's a link to the photo 

It appears to be reading it correctly however when I attempt to view the data there is nothing to see via the oscilloscope. Do you think I may need to increase my rate of output for the oscilloscope in order to get a reading?

Here's an update for the code.

[code]

byte sinewave[256] ={
127,130,133,136,139,143,146,149,152,155,158,161,164,167,170,173,176,178,181,184,187,190,192,195,198,200,203,205,208,210,212,215,217,219,221,223,225,227,229,231,233,234,236,238,239,240,
242,243,244,245,247,248,249,249,250,251,252,252,253,253,253,254,254,254,254,254,254,254,253,253,253,252,252,251,250,249,249,248,247,245,244,243,242,240,239,238,236,234,233,231,229,227,225,223,
221,219,217,215,212,210,208,205,203,200,198,195,192,190,187,184,181,178,176,173,170,167,164,161,158,155,152,149,146,143,139,136,133,130,127,124,121,118,115,111,108,105,102,99,96,93,90,87,84,81,78,
76,73,70,67,64,62,59,56,54,51,49,46,44,42,39,37,35,33,31,29,27,25,23,21,20,18,16,15,14,12,11,10,9,7,6,5,5,4,3,2,2,1,1,1,0,0,0,0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,10,11,12,14,15,16,18,20,21,23,25,27,29,31,
33,35,37,39,42,44,46,49,51,54,56,59,62,64,67,70,73,76,78,81,84,87,90,93,96,99,102,105,108,111,115,118,121,124

};

uint8_t divider = 24;
// set pin 10 as the slave select for the digital pot:

#define DATAOUT 51 // MOSI
#define DATAIN 50 // MISO //not used
#define SPICLOCK 52 // Clock
#define SELPIN 53 // chip-select
void setup() {

// set the slaveSelectPin as an output:
digitalWrite(SELPIN, HIGH);
pinMode(SELPIN, OUTPUT);
pinMode(SPICLOCK, OUTPUT);
pinMode(DATAOUT, OUTPUT);
// initialize SPI:
SPI.begin();
SPI.setClockDivider(SPI_CLOCK_DIV16); // slow the SPI bus down
Serial.begin(115200);
}

void loop() {
// go through the six channels of the digital pot:
for (int channel = 0; channel < 256; channel++) {
// change the resistance on this channel from min to max:
writeSPI(sinewave[channel]);
// wait a second at the top:
delay(100);
}

}

void writeSPI( byte value){ // I previously thought the DAC had multiple outputs (channels), it only has one
// and the mode control bits are inserted into the bit stream. I was wrong on how to send the data stream.

// configure SPI hardware for the maximum clock rate, bit order, clock phase and polarity

SPI.beginTransaction(SPISettings(14000000, MSBFIRST, SPI_MODE1)); // set correct SPI modes

// take the SS pin low to select the chip:

digitalWrite(SELPIN, LOW);

// send device Mode bits and the first 6bits of the DAC value via SPI:

byte output = value >>2; // the high bits b7, b6 need to be 0 for normal mode

// send the control bits plus the high 6 bits of the output value

SPI.transfer(output);

output = value << 6; // get the rest of the input value, the lower 2 bits of value, pad with zero's

SPI.transfer(output);

output = 0;
// Send a filler byte, the device expects 24 bits of data
SPI.transfer(output);

// take the SS pin high to de-select the chip:
digitalWrite(SELPIN, HIGH);
SPI.endTransaction(); // release SPI bus for other devices

}

[!code]