MSP432P401R Brushless motor DC

[Alejo96]

Hi all, my aim is to control a driver of a brushless motor by using 6 pins that come directly from 6 pins of my microcontroller (MSP432P401R), where 3 of them act as normal GPIO and represent the lower transistors (BA, BB, BC) and the other pins have the special function of PWM (TA,TB,TC) and share the same timer and port as well (P2.4, P2.5 and P2.6) respectively. The program is based on a FSM of 6 states and in each state there are 2 pins that stay HIGH and the rest stay LOW as it could be seen in the image above. The sequence is the one that appears in the image and when it arrives to the 6th state it starts over going to the 1rst state and so on. To sum up, TA, TB and TC are controlled using PWM and duty cycle is applied on them to take control of the speed of the motor and BA,BB and BC are normal GPIOs that could be HIGH or LOW depending on the state. My main problem is that I don't know how to switch between TA, TB and TC by applying PWM on one pin and disabling the PWM applied on another pin in the state before, like for example what happens then you reach the 3rd state and you should stop applying PWM to TA and start applying it on TB (hope it's clear). The code I wrote for this is the following one, but I know it has problems and if someone could help me understand what should I do and how to do it in a properly way, I would be really grateful!

#include "msp.h"
#define PWM 0x70 // 0111 0000
#define GPIO 0xE0 // 1110 0000
uint8_t estado = 0;

void inicializaciones(void){
/* TA: P2.4; TB: P2.5; TC: P2.6
* BA: P3.5; BB: P3.6; BC: P3.7
*/
// Pins Transistors HIGH (PWM)
P2->SEL0 |= PWM; // Configuramos los pines P2.4 (TA0.1), P2.5 (TA0.2) y P2.6 (TA0.3)
P2->SEL1 &= ~PWM;
P2->DIR |= PWM; // Para poner TA0.1, TA0.2 y TA0.3

// Pins Transistors LOW (GPIO)
P3->SEL0 &= ~GPIO;
P3->SEL1 &= ~GPIO;
P3->DIR |= GPIO; // output
}

void TimerA0(void){ // Timer para controlar los 3 pines PWM
TIMER_A0->CCTL[0] = TIMER_A_CCTLN_CCIE; // TACCR0 interrupt enabled
TIMER_A0->CCR[0] = 32767; // Periodo del PWM
TIMER_A0->CTL = TIMER_A_CTL_TASSEL_1 | TIMER_A_CTL_MC__UP; // Reloj ACLK (ACLK = TACLK = 32768H), Up Mode
}

void main(void)
{
WDT_A->CTL = WDT_A_CTL_PW | WDT_A_CTL_HOLD; // stop watchdog timer
inicializaciones();
__enable_irq(); // Enable global interrupt
TimerA0();

while(1){
switch(estado){
case 0: { // TA y BB HIGH
TIMER_A0->CCTL[1] = TIMER_A_CCTLN_OUTMOD_3 |TIMER_A_CCTLN_CCIE; // TACCR1 interrupt enabled; ModoCCR1: Set/Reset
P3->OUT |= (GPIO & ~(BIT7 | BIT5)); // 0100 0000, P3.6 (BB) HIGH
estado++;
}
case 1: { // TA y BC HIGH
P3->OUT |= (GPIO & ~(BIT6 | BIT5)); // 1000 0000, P3.7 (BC) HIGH
estado++;
}
case 2: { // TB y BC HIGH
TIMER_A0->CCTL[2] = TIMER_A_CCTLN_OUTMOD_3 |TIMER_A_CCTLN_CCIE; // TACCR2 interrupt enabled; ModoCCR1: Set/Reset
estado++;
}
case 3: { // BA y TB HIGH
P3->OUT |= (GPIO & ~(BIT7 | BIT6)); // 0010 0000, P3.5 (BA) HIGH
estado++;
}
case 4: { // BA y TC HIGH
TIMER_A0->CCTL[3] = TIMER_A_CCTLN_OUTMOD_3 |TIMER_A_CCTLN_CCIE; // TACCR3 interrupt enabled; ModoCCR1: Set/Reset
estado++;
}
case 5: { // BB y TC HIGH
P3->OUT |= (GPIO & ~(BIT7 | BIT5)); // 0100 0000, P3.6 (BB) HIGH
estado = 0;
}
}
}
}

void TA0_N_IRQHandler(void)
{
if(TIMER_A0->CCTL[1]&TIMER_A_CCTLN_CCIFG)
{
TIMER_A0->CCTL[1] &= ~TIMER_A_CCTLN_CCIFG;
TIMER_A0->CCR[1] = 8191; // f(ACLK)/4 = 8192Hz
}
if(TIMER_A0->CCTL[2]&TIMER_A_CCTLN_CCIFG)
{
TIMER_A0->CCTL[2] &= ~TIMER_A_CCTLN_CCIFG;
TIMER_A0->CCR[1] = 0; // Reset TA0.1
TIMER_A0->CCR[2] = 8191; // f(ACLK)/4 = 8192Hz
}
if(TIMER_A0->CCTL[3]&TIMER_A_CCTLN_CCIFG)
{
TIMER_A0->CCTL[3] &= ~TIMER_A_CCTLN_CCIFG;
TIMER_A0->CCR[2] = 0; // Reset TA0.2
TIMER_A0->CCR[3] = 8191; // f(ACLK)/4 = 8192Hz
}
if(TIMER_A0->CTL&TIMER_A_CTL_IFG)
{
// Clear timer overflow flag
TIMER_A0->CTL &= ~TIMER_A_CTL_IFG;
}
}

 

[shortbus=]

Hi all, my aim is to control a driver of a brushless motor by using 6 pins that come directly from 6 pins of my microcontroller

You mean that you will control mosfets from your micro to the motor, don't you? How, when doing this like your attempting, will you determine rotor position? The rotor position is needed to know what coils to turn on and when.

 

[MaxHeadRoom78]

Commutation sequence for BLDC motors | Lulu's blog

Commutation sequence for BLDC motors synchronised with Hall effect position sensors clockwise and counterclockwise. | Lulu's blog | Philippe Lucidarme

lucidar.me

 

[Alejo96]

You mean that you will control mosfets from your micro to the motor, don't you? How, when doing this like your attempting, will you determine rotor position? The rotor position is needed to know what coils to turn on and when.

I know that, but what I just want to do for now is an Open Loop solution, where I impose the period of the signal and I was wondering where my code is wrong as I don't get the sequence I wrote in the image above. So, my problem is on the manner on how to change between states and how to apply PWM in one pin of the uC for two states and then switch the same pulse PWM to the next pin for two states and same for the last two states and the last pin as well.

 

[MaxHeadRoom78]

You may get some help from the Picmicro site and their APP notes on 3ph & BLDC motor control.
They also have a BLDC development board that has a sample program.

 

[Alejo96]

You may get some help from the Picmicro site and their APP notes on 3ph & BLDC motor control.
They also have a BLDC development board that has a sample program.

Okay, thanks!