DAC81416EVM: No update on DAC outputs with Arduino SPI

Dharma Paladugu

Prodigy 20 points

Part Number: DAC81416EVM

Hi,

I am not seeing any output when using 81416EVM. Below are details about my setup.

I am using SPI on Arduino Due to update DAC voltages.

Please help.

Connections:

Arduino DUE SPI Pin 3 -> 81416EVM J8.8

Arduino DUE SPI Pin 4 -> 81416EVM J8.4

Arduino DUE 13 -> 81416EVM J8.2

Arduino DUE GND -> 81416EVM J1.31

J7.7 - 15V

J7.6 - GND

J7.5 - 5V

J7.4 - 3.3V

J7.3 - GND

J10: 2-3

Arduino IDE Code:

#include <SPI.h>
int CSdac =13; //Pin on Arduino connected to DAC on tuning board

void setup() {
SPI.beginTransaction(SPISettings(10000000, MSBFIRST, SPI_MODE1));
analogReadResolution(12);
SPI.begin(CSdac);
Serial.begin(115200);
pinMode(CSdac, OUTPUT);
digitalWrite(CSdac, HIGH);
}

void loop() {
Serial.println("Start");

// Set range 0-5V
digitalWrite(CSdac, LOW);
SPI.transfer(0x0A);
SPI.transfer(0x00);
SPI.transfer(0x00);
digitalWrite(CSdac, HIGH);

// Set range 0-5V
digitalWrite(CSdac, LOW);
SPI.transfer(0x0B);
SPI.transfer(0x00);
SPI.transfer(0x00);
digitalWrite(CSdac, HIGH);

// Set range 0-5V
digitalWrite(CSdac, LOW);
SPI.transfer(0x0C);
SPI.transfer(0x00);
SPI.transfer(0x00);
digitalWrite(CSdac, HIGH);

// Set range 0-5V
digitalWrite(CSdac, LOW);
SPI.transfer(0x0D);
SPI.transfer(0x00);
SPI.transfer(0x00);
digitalWrite(CSdac, HIGH);

// Power up device
digitalWrite(CSdac, LOW);
SPI.transfer(0x03);
SPI.transfer(0x0A);
SPI.transfer(0x84);
digitalWrite(CSdac, HIGH);

// Power up all channels
digitalWrite(CSdac, LOW);
SPI.transfer(0x09);
SPI.transfer(0x00);
SPI.transfer(0x00);
digitalWrite(CSdac, HIGH);

// Enable broadcast all channels
digitalWrite(CSdac, LOW);
SPI.transfer(0x05);
SPI.transfer(0xFF);
SPI.transfer(0xFF);
digitalWrite(CSdac, HIGH);

// Write code to all channels
digitalWrite(CSdac, LOW);
SPI.transfer(0x0F);
SPI.transfer(0xFF);
SPI.transfer(0xFF);
digitalWrite(CSdac, HIGH);

delay(100000000);
}

over 2 years ago

0 Anbu Mani over 2 years ago

TI__Expert 4110 points

Hi Dharma,

The hardware configuration and register writes are seems correct. please share the oscilloscope snaps of SPI lines(CS, SCLK, SDI, SDO). We will see if is there any timing issue there.

0 Dharma Paladugu over 2 years ago in reply to Anbu Mani

Prodigy 20 points

Hi Anbu,

Here is a screenshot of SPI. I just tried writing a single 8 bit data (0x0A) to check the validity of data.

Is the device in power down mode by default? If yes, how to change it?

Also is there anything to do with TOGGLE pins?

0 Dharma Paladugu over 2 years ago in reply to Dharma Paladugu

Prodigy 20 points

Hi,

I can see a 10KOhm resistance with multimeter connected between GND (J1.31) and OUT8 (J1.2). So I am guessing the DAC is not getting powered on.

This is an urgent requirement. Please let me know if I am missing something.

+1 Anbu Mani over 2 years ago in reply to Dharma Paladugu

TI__Expert 4110 points

Hi Dharma Paludugu,

It seem you SPI timing is wrong.

Host controller must place the data on SDI at rising edge of SCLK and device will sample falling edge of SCLK.

Change SPI operating mode as SCLK (CPOL =0 , CPHA =1) and try.

0 Dharma Paladugu over 2 years ago in reply to Anbu Mani

Prodigy 20 points

Hi,

I used SPIMODE1 in Arduino. It has CPOL=0, and CPHA = 1.

I will check again. Appreciate your response.

Is of your colleagues in US time zone to help me during the day too?

0 Dharma Paladugu over 2 years ago in reply to Anbu Mani

Prodigy 20 points

SPI mode is the issue. The Arduino I am using does not change the mode even though I use different mode in the code. Once it is fixed it is straightforward.

Thanks.

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DAC81416EVM: No update on DAC outputs with Arduino SPI