KXTJ3 I2C Tri-axis Accelerometer not outputting negative g's

Other Hardware Sensors
1

Hi, I am having trouble with a Kionix accelerometer (tri-axis). As you can see, I have tried multiple things to alleviate my problem but to no avail.
While I can get the accelerometer to give me values and about half of them are valid, the other half aren't. When the accelerometer is in the 0 position and as I turn in the positive X direction, the values go from 0 to 64 (rawcount) and then from 64 back to 0. By this point, the device has turned 180 degrees, on the 181 degree, the output is 255 and that value goes to 225 where it will increase back to 255 it reaches 0 again in the original position.
I thought the readings should go from 0 to 64 and back down to 0, and then start the negative readings. Below is my code and attached is the datasheet and a getting started guide.
*Note, this happening on multiple devices I have. Tested on Terminal window in sketch and an OLED display.

//Include Files
#include <Arduino.h>
#include <SPI.h>
#include <Wire.h>
#include <U8x8lib.h>
#include <math.h>		/* Include math header file */

//Globals
int z_angle,r_AcX,r_AcY,r_AcZ;
uint16_t AcX,AcY,AcZ;
const int kio_addr = 0x0F; //I2C address of the KXTJ3
const int CNTL1 = 0x1B; //Control Register 1
const int DCR = 0x21; //Output Data Rate Control Resister
const int V1 = 0X00; // Value sent to CNTL2, Disable Sensor
const int V2 = 0x02; //Value Sent to Output Data Rate Control Register
const int V3 = 0xC0; //Set CNTL1 to high resolution and range at 2g, Enable Operating mode
char bufferx[80];

void setup() 
{
	Wire.begin();
	Wire.beginTransmission(kio_addr);
	Wire.write(CNTL1);
	Wire.write(V1);
	Wire.endTransmission(true);
	Wire.beginTransmission(kio_addr);
	Wire.write(DCR);
	Wire.write(V2);
	Wire.endTransmission(true);
	Wire.beginTransmission(kio_addr);
	Wire.write(CNTL1);
	Wire.write(V3);
	Wire.endTransmission(true);
	Serial.begin(9600);
}

void loop() 
{	
	Wire.beginTransmission(kio_addr);
	Wire.write(0x07);  // starting with register 0x06 (ACCEL_XOUT_H)
        //Wire.write(0x06);  // starting with register 0x06 (ACCEL_XOUT_L)
	//Wire.write(0x08);  // starting with register 0x06 (ACCEL_YOUT_L)
	//Wire.write(0x0A);  // starting with register 0x06 (ACCEL_ZOUT_L)
	//Wire.endTransmission(false);
	Wire.endTransmission();
	//Wire.requestFrom(kio_addr,12);  // request a total of  registers
	Wire.requestFrom(kio_addr,1);  // request a total of  registers
	if(Wire.available() <=1)
	{
		AcX = Wire.read();
	}
	//AcX = Wire.read()<<12|Wire.read();  // 0x07 (ACCEL_XOUT_H) & 0x06 (ACCEL_XOUT_L)    
	//AcY = Wire.read()<<12|Wire.read();  // 0x09 (ACCEL_YOUT_H) & 0x08 (ACCEL_YOUT_L)
	//AcZ = Wire.read()<<12|Wire.read();  // 0x0B (ACCEL_ZOUT_H) & 0x0A (ACCEL_ZOUT_L)
	if(AcX >= 0)
	{
		r_AcX = round(AcX); //Raw x Rounded
		//int to string
		sprintf(bufferx,"Xaccel %d",r_AcX);		
	}
	else
	{
		r_AcX = round(AcX*-1); //Raw x Rounded
		//int to string for OLED Display
		sprintf(bufferx,"Xaccel -%d",r_AcX);
	}
	//r_AcX = round(AcX); //Raw x Rounded
	//r_AcY = round(AcY); //Raw y Rounded
	//r_AcZ = round(AcZ); //Raw z Rounded
	//z_angle = round(acos(AcZ/64)*57.29577951);
	//sprintf(buffery,"Yaccel %d",r_AcY);
	//sprintf(bufferz,"Zaccel %d",r_AcZ);
	//sprintf(bufferz,"%d",z_angle);
	//Serial.print("AcX = "); Serial.println(AcX);
	//Serial.print(" | AcY = "); Serial.println(AcY);
	//Serial.print(" | AcZ = "); Serial.println(AcZ);
	delay(100);
}

AN065-Getting-Started.pdf (493 KB)

2

I don't use that sensor, but I can see lots and lots of problems with the code.

All of these values are for eight bit addresses and data registers. So why have you declared them as "ints"? Wire.write() expects to send a byte.

const int kio_addr = 0x0F; //I2C address of the KXTJ3
const int CNTL1 = 0x1B; //Control Register 1
const int DCR = 0x21; //Output Data Rate Control Resister
const int V1 = 0X00; // Value sent to CNTL2, Disable Sensor
const int V2 = 0x02; //Value Sent to Output Data Rate Control Register
const int V3 = 0xC0; //Set CNTL1 to high resolution and range at 2g, Enable Operating mode

In the following, Wire.requestfrom() is a complete transaction. It either works or it does not. This call would get one byte from the device.

Wire.requestFrom(kio_addr,1);  // request a total of  registers

This statement says that if zero bytes have been read and are available, read them anyway. But it will work, because the previous command will have already retrieved one byte.

if(Wire.available() <=1)
	{
		AcX = Wire.read();
	}

Unless you have set eight bit mode, the X acceleration is in contained in two bytes. The fact that you read only one byte probably explains why you cannot interpret the results.

Strong hint: google "arduino kxtj3" to find a couple of libraries for that device. Study the documentation and examples, then use them wisely.

3

As a design engineer, my firmware abilities are lacking especially with it comes to the data types. But I'm learning. As for the your strong hint, I spent hours googling things about this topic and didn't find what I found until I inputted exactly what you said. So thank you.