UM0324 datasheet(78/105 Pages) STMICROELECTRONICS

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Library functions

UM0324

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TAC_GetRotorFreq

GetLastTachoPeriod

GetAvrgTachoPeriod

Synopsis

u16 TAC_GetRotorFreq (void)

Description

This routine returns rotor frequency with a unit that can be directly

integrated (accumulated) to get the rotor angular position in the main

control loop.

Input

None.

Output

Rotor mechanical frequency with rad/PWM period unit

π rad = 0xFFFF), assuming the control loop is executed in each

and every PWM interrupt service routine.

Functions called

GetAvrgTachoPeriod, GetLastTachoPeriod (both private functions)

Note

Result is zero if speed is too low (glitches at start for instance).

Excessive speed (or glitches) will result in a pre-defined value

returned (see Section 2.2.4 on page 21).

Maximum expectable accuracy depends on CKTIM: 60MHz will give

the best results.

Caution

This routine returns the mechanical frequency of the rotor. To find the

electrical speed, use the following conversion:

electrical frequency = mechanical frequency * number of pole pairs

Synopsis

u32 GetLastTachoPeriod(void)

Description

This routine returns the rotor period based on the last tacho capture.

Input

None.

Output

Tacho signal period, unit is 1 CKTIM period, unsigned 32-bit format.

Functions called

None.

Note

This function is private to the 75x_tacho.c module.

Synopsis

u32 GetAvrgTachoPeriod(void)

Description

This routine returns returns the rotor period based on the average of

the four last tacho captures.

Input

None.

Output

Tacho signal period, unit is 1 CKTIM period, unsigned 32-bit format.

Functions called

None.

Note

This function is private to the 75x_tacho.c module.

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