DAC81416: DAC SPI MCU PROGRAM EXAMPLE

Hi,

We don't have code examples specific to Teensy MCU board. Below code examples for Energia sketch

#include <SPI.h>

#define NUM_BYTES 3 //Number of bytes in SPI frame

//SPIClass tivacSPI0(0); // SSI0
//SPIClass tivacSPI1(1); // SSI1
//SPIClass tivacSPI2(2); // SSI2
//SPIClass tivacSPI3(3); // SSI3 on port F
SPIClass tivacSPI3_Q(4); // SSI3 on port Q

void setup() {
uint8_t initTx0[NUM_BYTES], initTx1[NUM_BYTES], initTx2[NUM_BYTES], i;
int8_t ret;
uint8_t *initPtr;

Serial.begin(9600);
Serial.print("Starting DAC81416 Example");

//tivacSPI0.begin();
//tivacSPI1.begin();
//tivacSPI2.begin();
//tivacSPI3.begin();
tivacSPI3_Q.begin();

pinMode(PD_2, OUTPUT); // Configure PD2 as CLR
digitalWrite(PD_2, HIGH); // set CLR HIGH by default

//Range: +/- 20V
initTx0[0] = 0x0A;
initTx0[1] = 0xCC;
initTx0[2] = 0xCC;
initPtr = &initTx0[0];
ret = tivacSPI3_Q.DACtransfer((uint8_t*)initPtr, (uint8_t)NUM_BYTES);

//Range: +/- 20V
initTx0[0] = 0x0B;
initTx0[1] = 0xCC;
initTx0[2] = 0xCC;
initPtr = &initTx0[0];
ret = tivacSPI3_Q.DACtransfer((uint8_t*)initPtr, (uint8_t)NUM_BYTES);

//Range: +/- 20V
initTx0[0] = 0x0C;
initTx0[1] = 0xCC;
initTx0[2] = 0xCC;
initPtr = &initTx0[0];
ret = tivacSPI3_Q.DACtransfer((uint8_t*)initPtr, (uint8_t)NUM_BYTES);

//Range: +/- 20V
initTx0[0] = 0x0D;
initTx0[1] = 0xCC;
initTx0[2] = 0xCC;
initPtr = &initTx0[0];
ret = tivacSPI3_Q.DACtransfer((uint8_t*)initPtr, (uint8_t)NUM_BYTES);

//Power-up device
initTx0[0] = 0x03;
initTx0[1] = 0x0A;
initTx0[2] = 0x84;
initPtr = &initTx0[0];
ret = tivacSPI3_Q.DACtransfer((uint8_t*)initPtr, (uint8_t)NUM_BYTES);

//Power-up all channels
initTx0[0] = 0x09;
initTx0[1] = 0x00;
initTx0[2] = 0x00;
initPtr = &initTx0[0];
ret = tivacSPI3_Q.DACtransfer((uint8_t*)initPtr, (uint8_t)NUM_BYTES);

//Enable Broadcast for all Channels
initTx0[0] = 0x05;
initTx0[1] = 0xFF;
initTx0[2] = 0xFF;
initPtr = &initTx0[0];
ret = tivacSPI3_Q.DACtransfer((uint8_t*)initPtr, (uint8_t)NUM_BYTES);

//Write Code to all Channels
initTx0[0] = 0x0F;
initTx0[1] = 0xFF;
initTx0[2] = 0xFF;
initPtr = &initTx0[0];
ret = tivacSPI3_Q.DACtransfer((uint8_t*)initPtr, (uint8_t)NUM_BYTES);
}

void loop() {
int8_t rv, ldacFlag = 0;
int32_t sampleCount;
uint8_t *txPtr;
uint8_t spiTx0[NUM_BYTES];

//Write Mid-code
spiTx0[0] = 0x10;
spiTx0[1] = 0x7F;
spiTx0[2] = 0xFF;
txPtr = &spiTx0[0];
rv = tivacSPI3_Q.DACtransfer((uint8_t*)txPtr, (uint8_t)(NUM_BYTES));

delay(100);

//Write Full-code
spiTx0[0] = 0x10;
spiTx0[1] = 0xFF;
spiTx0[2] = 0xFF;
txPtr = &spiTx0[0];
rv = tivacSPI3_Q.DACtransfer((uint8_t*)txPtr, (uint8_t)(NUM_BYTES));

delay(100);
}

//Addition to SPI.cpp

int8_t SPIClass::DACtransfer(uint8_t* datapointer, uint8_t numBytes) {
unsigned long rxtxData[MAX_BYTES];

if(numBytes > MAX_BYTES){
return -1;
}
if(datapointer == NULL){
return -1;
}

for(int byteCount=0; byteCount < numBytes; byteCount++){
rxtxData[byteCount] = datapointer[byteCount];
}
if(SSIBitOrder == LSBFIRST) {
return -1;
}
for(int byteCount=0; byteCount < numBytes; byteCount++){
ROM_SSIDataPut(SSIBASE, (uint8_t) rxtxData[byteCount]);
}

while(ROM_SSIBusy(SSIBASE));

return (int8_t) 0;
}


In case, you need a generic setting for SPI on any processor. It's as follows:

Mode: Mode-1 (CPOL=0, CPHA=1)
Order: MSB First
CS Polarity: Active Low
Number of Bytes: 3

You can use GPIOs for LDAC and CLR, if needed.

Regards,

AK

Hi Akhilesh,

Akhilesh K said:

unsigned long rxtxData[MAX_BYTES];

What is the variable MAX_BYTE ?

I get this error

teensy_SPI:149: error: 'MAX_BYTES' was not declared in this scope
   unsigned long rxtxData[MAX_BYTES];