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ams Datasheet

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[v1-01] 2016-Apr-11

AS5170 − Application Information

Signature Calculation

The OTP of AS5170A and AS5170B uses a BIST technique with

Multiple Input Signature Register circuits.

To activate this BIST a calculation of the Signature Byte is

necessary and has to store into the OTP during the

programming sequence.

For calculating the signature byte the content of the whole

memory (0x02 to 0x1D) has to be read.

Out of this information the following calculation has to be done.

Byte: 0x02 = data2

….

Byte: 0x1D = data29

Unsigned int signature (unsigned int * content)

{

unsigned int misr,misr_shift,misr_xor,misr_msb;

misr = 0;

for (int i=0; i<28; i++) {

misr_shift = (misr<<1);

misr_xor = (misr_shift ^ content[i])%256;

misr_msb = misr/(128);

if (misr_msb == 0)

misr = misr_xor;

else

misr = (misr_xor ^ 29)%256;

}

return misr;

}

content= {,data2,data3,data4,data5,data6,

data7,data8,data9,data10,data11,

data12,data13,data14,data15,data16,

data17,data18,data19,data20,data21,data22,

data23,data24,data25,data26,data27,data28,data29};

Application Information

AS5170 Datasheet(PDF) 32 Page - ams AG