Kontron pITX-SP - Manual (Page 38)

KTD-S0003-C Page 34 Tri-Axis Accelerometer Example
p ITX-SP Software Guide
byte ReadReg (byte reg)
{
union REGS regs;
regs.h.ah = SMBUS_ENTRY;
regs.h.al = SMBUS_READ_BYTE;
regs.h.bh = DEVICE_ADDR;
regs.h.bl = reg;
int86 (INT_SERVICE, &regs, &regs);
return regs.h.cl;
}
double TransformValue (word val, word *sg)
{
*sg = FALSE;
if (val & 0x8000)
{
*sg = TRUE;
val ^= 0xFFFF;
val &= 0x1FFF;
val ++;
}
return ((double) val / (double) 1024);
}
void main (void)
{
word
acc, sign;
byte acc_lo, acc_hi;
double resX, resY, resZ, resAll;
int ch;
char str [64];
clrscr ();
gotoxy (1,1);
printf ("Accelerometer Test Program");
while (TRUE)
{
WriteReg (PAGE_REG, PAGE0); // Set page 0
WriteReg (OP_MODE_REG, START_MEASURE); // Start measurement
delay (1);
WriteReg (PAGE_REG, PAGE1); // Set page 1
while (TRUE)
{
if (! ReadReg (STATUS_REG)) // Read status
break;
}
acc_lo = ReadReg (XAXIS_REG); // Read X value
acc_hi = ReadReg (XAXIS_REG+1);
acc = ((word) acc_hi * 256) + (word) acc_lo;
resX = TransformValue (acc, &sign);