RM0020 datasheet(35/69 Pages) STMICROELECTRONICS

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RM0020

Function API

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Arguments:

Description:

Pressure sensing function 2. The function is used for in-cylinder pressure sensor

management. This function should follow the mfb50_pmh function call. The function

searches the mass fraction burned (MFB) vector and returns index at which the

MFB50 value was found. The returned index is called MFB50% position index.

Algorithm:

For each i = 2,3 ... N-2, calculate absolute value of difference MFB[i] and MFB50:

Equation 33

Find index i at which the diff[i] has minimal value.

Note: There must be 8 bytes of readable memory behind input vector MFB.

Performance: See Section 7 and Table 47.

Example 16. mfb50_index

#include "libdsp2.h"

float P[740];

float V[740];

float K = 1.4F;

unsigned int N = 714;

float PMH;

unsigned int MFB50_index;

float MFB50;

void main(void)

{

/* from pressure vector P and volume vector V, calculate MFB50

value, PMH index and mass fraction burned (MFB), MFB

returned back in P vector, MFB1 at P array position 0 */

MFB50 = mfb50_pmh(N, P, V, K, &PMH);

/* search for MFB50 value in mass fraction burned (P) vector and

return index at which the MFB50 value was found */

MFB50_index = mfb50_index(N, P, MFB50);

}

Table 16.

mfb50_index arguments

Nin

length of mass fraction burned vector MFB, N-2 must be multiple of

4, N must be greater than or equal to 10

MFB(1)

The MFB vector must be double word aligned.

pointer to the input mass fraction burned vector of length N, layout

is MFB(1) MFB(2) ...MFB(N-2) MFB(N-1) 0, use vector calculated

by mfb50_pmh function

MFB50

MFB50 value, use value returned by mfb50_pmh function

diff i



MFB i

 MFB50

–

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