LTC1605 obtaining accurate voltage value

I’ve been playing with the LTC1605 and a mcp9701 temperature sensor with my 2560 mega (just ordered the MCP3208, way less pins to deal with.) In order to get an accurate voltage value, I have to use 5.0*adcvalue/16384 to get an accurate voltage value. From the datasheet the data is two’s complement, so the MSP is used to tell if the number is negative or not so the number of possibilities should be 2^15, but for some reason I have to base my calculation on 2^14 to get an accurate voltage value. What am I doing wrong? This is my first time with working with an external ADC.

Datasheet:
http://cds.linear.com/docs/en/datasheet/1605fc.pdf

Pin 22 is connected to D15
Pin 37 is connected to D0
The BYTE pin is held LOW

float adc;

int cs=51; //pin number connected to the CS pin
int rc=52; //pin number connected to the RC pin
//temp to voltage 
//volts per step = 5/16384

void setup() {
Serial.begin(9600);
pinMode(cs,OUTPUT);
pinMode(rc,OUTPUT);
digitalWrite(cs,HIGH);
digitalWrite(rc,HIGH);
}
void loop() {
  // put your main code here, to run repeatedly: 
  adc=0;
  inital();
  readdata();
  Serial.println(adc);
  temps();
  delay(3000);
}



void inital(){
digitalWrite(cs,LOW);
digitalWrite(rc,LOW);

//delayMicroseconds(1);
//
digitalWrite(rc,HIGH);
digitalWrite(cs,HIGH);  
}

void readdata(){

 int count=22;
 float  val2=65536;
 while((count)<=37){
   val2=val2/2;
  if (digitalRead(count)==HIGH){
   adc=adc+val2;
   } 
   count++;
 }
}
 void temps(){
  float temp=5.0*adc/16384;
 temp= (temp-.5)/.010;
 temp = 9/5.0*temp + 32.0;
 Serial.println(temp);
 }

Where do you take into account the sign of the converted voltage (D15)? This converter is designed for +/- 10V input, so for 10V input, you would expect to read 32767 and for 5V, 16383.

jremington: Where do you take into account the sign of the converted voltage (D15)? This converter is designed for +/- 10V input, so for 10V input, you would expect to read 32767 and for 5V, 16383.

I didn't take into account the sign of the converted voltage as I don't have any negative voltages in my application(should have just took the part of reading D15 out of my sketch) . Thanks for the answer.