Leading zeros when using SPI?

Projects Programming
1

Hi, I'm relatively new to programming, but not hardware. I'm trying to use the SPI library but I'm having issues. What i need to do is send a 10 bit word to an IC (cs4192, it's an air core driver) if i use SPI.transfer(variable); MSB first it will not transfer the full width of the data type (unsigned int, int whatever i choose) and therefore it will throw the gauge off. for example if I want to tell it position 2, it would send "10" binary, instead what I need is "0000000010". I'm a complete noob here and I have no clue where to even start, I've been searching for "zero padding spi" but have turned up empty. Any help is greatly appreciated, an explanation or a turn in the right direction is even better.

2

Sounds like you should be using a variable of type uint_16t. Set that variable to 2 (or whatever you want) and then have the Arduino send the variable over SPI.

Can you post your code?

3

Power_Broker:
Sounds like you should be using a variable of type uint_16t. Set that variable to 2 (or whatever you want) and then have the Arduino send the variable over SPI.

Can you post your code?

here is my code, I will change the data type right now and try that.

you know what, after that suggestion i did some digging, i found a SPI.transfer16(); which includes the leading zero's now it works perfectly. Thank you for sparking that!

#include <SPI.h>



const int slavePin = 53;
SPISettings settings(20000, MSBFIRST, SPI_MODE1); 
int gaugePos = 1024;
int stepAmount = 1;


void setup() {
  // set the Slave Select Pin as an output:
  pinMode (slavePin, OUTPUT);
  // initialize SPI:
  SPI.begin(); 
}

void loop() {

  SPI.beginTransaction(settings);
  digitalWrite (slavePin, HIGH);
  SPI.transfer(gaugePos);
  digitalWrite (slavePin, LOW);
  SPI.endTransaction();
  delay(1000);
  gaugePos = gaugePos + stepAmount;
  delay(100);

  // reverse the direction of the gauge at the ends of the travel:
  if (gaugePos <= 0 || gaugePos >= 1024) {
    stepAmount = +stepAmount;}

  }