AN1905 datasheet(21/77 Pages) STMICROELECTRONICS

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ST7MC THREE-PHASE BLDC MOTOR CONTROL SOFTWARE LIBRARY

3.5 USING YOUR OWN POWER STAGE

In order to configure the standalone library to match any kind of power stage, care should be

taken to observe the logic input diagrams of the drivers. The starter kit uses three L6386 high-

voltage high and low side drivers; other devices may require adjustments, depending on

whether their logical inputs are active low or high. The ‘MPOL’ register has then to be set man-

ually in the firmware. Modifications can be done in the ‘MTC_InitPeripheral’ routine (see

Figure 9). It has to be noted also that the option byte has to be updated accordingly (MCO

output states during reset).

Figure 9. MPOL register configuration

The starter kit can also be connected directly to an external power stage using the socket J6

(26 pins).

3.6 CHECKING THE CURRENT SENSOR RESISTOR VALUE

The starter kit comes with a current sensor resistor of 0.047 Ohm (R21 on the schematic, see

Figure 10). The current limiter of the MTC cell relies on a comparator that turns off the PWM

when the voltage on this resistor has reached a limit (see Section 7.2.1 Voltage versus current

mode for more details). This voltage is amplified by a factor of 11 by the internal OPAMP con-

figured as a non-inverter amplifier (see R66 and R67 values).

void MTC_InitPeripheral(void)

{

MTC_ResetPeripheral();

// Initialize registers in page 1 first

SET_MTC_PAGE(1);

MCONF = mem_MCONF;

MPWME = (u8)(mem_MPWME | DG_MSK); //Force output of debug signal

MPOL = ALL_ACTIVE_HIGH;

// (L6386D) <-- to be updated according to your own

device characteristics

// ZVD bit=0; Z and D have opposite edge

AN1905 Datasheet(PDF) 21 Page - STMicroelectronics