[Isentek] eCompass API Quick Start

eCompass API quick start
Alex.Hsieh
2016.11.10
V2.0.1

Outline
• eCompass API library
• PCB Sensor direction and coordinate system
• Sample code
• API Manual (chm)
• FAQ

eCompass API library & manual
• Check 5 files for eCompass API library
1) Sample code folder
2) Config.h
3) IST_LIB.h
4) IST_LIB.c
5) eCompass API.chm

eCompass API library
• Include 2 header file (.h) and 1 source file (.c) in
your project - Config.h / IST_LIB.h / IST_LIB.c
• Copy essential part from sample code - Main.c

PCB Sensor direction and coordinate system
• Change mag and acc sensor axis direction (x, y,
z) to fit coordinate system (N, E, U)
PCB Sensor direction

• Change sensor axis direction (x, y, z) to fit
coordinate system (N, E, U)
X
Y Z
X’
Y’Z’
X’ = -Y
Y’ = -X
Z’ = Z
X’
Y’Z’
X
Y Z
E
N
U
E
N
U
E
N
U
E
N
U

• Change mag sensor data (x, y, z) from LSB to
uT and axis direction • X’ = -Y * Mag_LSBtoUT
• Y’ = -X * Mag_LSBtoUT
• Z’ = Z * Mag_LSBtoUT
• Mag_LSBtoUT = 0.3

Sample code
• Steps
1) Copy sample code and enable the essential function
in your project
• Set_HeadingAngleEnable
• Set_MagAccuracyEnable
• Set_SingleCalibration / Set_DynamicCalibration
2) Input data need mag and acc data, if you don’t have
acc data, please input [0,0,9.8]
3) Check the input data axis direction to fit NEU
system

Sample code
• Include header file

Sample code
• Variable and compass API initialization (A and B
part.)

Sample code
• Part B : isentek compass initialization stage
• ist8310_Init(); // init driver
• Set_HeadingAngleEnable(IST_TRUE);// if return Heading angle, it need acc
and mag sensor
• Set_MagAccuracyEnable(IST_TRUE);// if enable eCompass accuracy report -
return 0:unreliable 3:High 2:medum 1: low
• Set_SingleCalibration(IST_TRUE);// if enable single calibration right now
• Set_DynamicCalibration(IST_TRUE) ;// if enable continuous calibration
• Set_MagBias(Mag_IST8310_Bias);
// if you have last calibrated value and don't calibrate again, you can set by this
"Set_MagBias" function
// note : this setting dependent on your application, please check if you
applciation is suitable

Sample code
• Run process in while loop (C1-C6 part.)

Sample code
• Run process in while loop (C1 & C2 part.)
// C1. Get mag and acc data from driver and change the sensor value from LSB
to uT
ist8310_GetXYZ(MagXYZ);
for (int i = 0; i < 3; ++i) {
Mag_RawData[i] = (float)MagXYZ[i] * Mag_LSBtoUT;
}
// C2. Dependent on PCB layout, change the mag and acc direction to NEU (x =
east, y = west, z = up)
Mag_RawData[0] = Mag_RawData[0];
Mag_RawData[1] = -Mag_RawData[1];
Mag_RawData[2] = Mag_RawData[2];
AccData[0] = AccData[1];
AccData[1] = AccData[0];
AccData[2] = AccData[2]; PCB Sensor direction

Sample code
// C3. Run Compass Process to get Calibrated Data
// Here, we use constant acc data input [0,0,9.8], also, acc data [0,0,1] is ok.
Process_RunCompass(Mag_RawData, AccData, Mag_CalibratedData);
// C4. Check Calibration Status
// Mag_CalibrationStatus : In calibration = 1, no = 0
// Get_MagBias : BiasX, BiasY, BiasZ, Radius
// Mag_GetIST8310_Bias element will have valid value after calibration,
// you can check the bias value to know process finish calibration.
Mag_CalibrationStatus = Get_CalibrationStatus();
Get_MagBias(Mag_GetIST8310_Bias);

Sample code
// C5. Get Heading Angle
// Get_HeadingAngle return int type angle. 0 - 360 degree
// Get_HeadingAngle100 return int type angle . 0 - 36000 degree
// Therefore, we need to change angle type
Mag_HeadingAngle = (float)Get_HeadingAngle();
Mag_HeadingAngle_Int100 = 0.01f * ((float)Get_HeadingAngle100());
// C6. Get Mag Accuracy Status
// 0:unreliable 3:High 2:medum 1: low
Mag_Accurancy = Get_MagAccuracyStatus();

API Manual (chm)
• File list – inc – IST_LIB.h

API Manual (chm)
• Function list

API Manual (chm)
• Function detail

FAQ
• IST_A001 – What’s the LSB to uT?
• IST_A002 – Why do we change the axis of acc and mag sensor to
NEU system?
• IST_A003 – What’s the difference and priority between
Set_SingleCalibration and Set_DynamicCalibration API?
• IST_A004 – How to calibrate eCompass correctly?
• IST_A005 – What’s the definition for 0, 1, 2, 3 in accuracy report ?
• IST_A006 – What time do I use “Set_MagBias” function?

[Isentek] eCompass API Quick Start

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