SPI - CC3200 Master - TPL0501 Slave

[UTDesign 0]

Hello all,

I'm having trouble getting my digital pot to respond to the CC3200.  Could someone please take a look at my code and let me know where I'm going wrong? Thanks.

 

DataSheet for the digital pot; http://www.ti.com/product/tpl0501-100

 

#include <SPI.h>

 

const int SS = 8;

uint8_t value;

int volts = 0;

void setup()

{

  Serial.begin(9600);

  pinMode(SS, OUTPUT);

  SPI.begin();

  delay(100);

}

 

void loop()

{

  for(value = 0; value < 256; value += 20)

  {

  digitalWrite(SS, LOW);

  delay(10);

  SPI.transfer(value);

  delay(10);

  digitalWrite(SS,  HIGH);

  delay(100);

  }

}

 

[Rei Vilo 695]

Four suggestions:

• Just after pinMode(SS, OUTPUT);set digitalWrite(HIGH); to avoid any interference.
• Check you're using the correct pins of SPI.
• Try slower speeds with SPI.setClockDivider().
• Check SPI mode and use SPI.setDataMode() accordingly.

[UTDesign 0]

Something like this?

 

The data sheet says that the digipot is write only:

 

8bit   -   MSBFirst   -  CS~ low to enable write   -   24MHZ max clock

 

That would be SPI_MODE1 as I understand it, right?

And divide by 4 should reduce the 80MHZ CC3200 clock to a 20MHZ which is below the digipot max.

 

  

#include <SPI.h>

 

const int SS = 8;

uint8_t value;

void setup()

{

  pinMode(SS, OUTPUT);

  digitalWrite(SS, HIGH);

  SPI.setBitOrder(MSBFIRST);

  SPI.setDataMode(SPI_MODE1);

  SPI.setClockDivider(SPI_CLOCK_DIV4);

  SPI.begin();

  delay(100);

}

 

void loop()

{

  for(value = 0; value < 256; value += 20)

  {

  digitalWrite(SS, LOW);

  delay(10);

  SPI.transfer(value);

  delay(10);

  digitalWrite(SS,  HIGH);

  delay(100);

  }

}

[Rei Vilo 695]

Do you have a logic analyser?