DRV8301: DRV8301 GVDD is always LOW

Hi Rick,

       Thanks for your reply,

Yes, powerPAD is connected to ground.

And EN_GATE is logic high before starting with anything and I wait for 20 msec after EN_GATE is high.

AVDD = 6.3V

DVDD = 2.7V

GVDD = 0.1V

No motor is not connected to circuitry.

I tried reading SPI registers but no luck and I believe it is because of undervoltage shutdown as SPI block stops responding to external commands (as per the datasheet).

Hi Rick,
I just manually connected ground pin to EN_BUCK (pin 55 of DRV8301 IC) and PWM is suddenly working. Prior to connecting EN_BUCK to ground its voltage was 2.7V. But just as I ground EN_BUCK PWM and SPI are working fine.
I have set always,
PVDD1 = 24V
PVDD2 = 24V

and If EN_BUCK = 0V (manually connected to ground)
GVDD = 11V
AVDD = 6.3V
DVDD = 3.3V
is observed.

and If EN_BUCK = 2.2V (left floating)
GVDD = 0.1V
AVDD = 6.3V
DVDD = 2.7V
is observed.

Q1: I'm keeping EN_BUCK to 0V for now but what should be its value ideally?

Q2: Also I'm writting 3-phase command to SPI with register value of 0x1008 and when I read it for the first time I get 0x1008 as return value which is I believe correct for 3-pwm mode. But when I try to read same register again then I just get 0x1400 as return value. Why is 0x1008 overwritten automatically if that's what happened?

Q3: Sometimes SPI just returns 0x0000 or i.e. doesn't return anything and in that case I keep reading with the same command then with tries of 2 or 3 I get success. Why is SPI communication unreliable?

Q4: Even when I do not apply PWM and EN_BUCK=0V then there is by default a PWM signal of 3.3V at the GX_X pins of DRV8301. When I apply PWM at INX_X pins I get output very noisy PWM (not rectangular in shape but shape like that of capacitor charging) of 5V only, how do I increase this output voltage of PWM to say 8V??

I'm using following code on arduino mega,

#include <SPI.h>
const int HpinA =11;
const int LpinA =10;
const int HpinB =9;
const int LpinB =6;
const int HpinC =5;
const int LpinC =3;
const int chipSelectPin = 53;
const int EN_GATE = 8;
boolean is3PMWmode = false;
byte Hcheck3PWM = 0x00,Lcheck3PWM = 0x00;
void setup() {
Serial.begin(9600);
pinMode(chipSelectPin, OUTPUT);
pinMode(EN_GATE, OUTPUT);
digitalWrite(EN_GATE, LOW);
digitalWrite(chipSelectPin, LOW);
SPI.begin();
// DRV8301 communicates with MSB first and has low clock polarity and data is shifted on rising edge
// SPI.beginTransaction(SPISettings(4000000, MSBFIRST, SPI_MODE1));
SPI.setBitOrder(MSBFIRST);
SPI.setDataMode(SPI_MODE1); // While Idle SPI CLK = 0, falling Egde latching for Rx
digitalWrite(EN_GATE, HIGH);
delay(20); // Start up time
}

void loop() {
if(Hcheck3PWM == 0x10 && Lcheck3PWM == 0x08){
is3PMWmode = true;
runPWM();
}
if(!is3PMWmode){
writeRegister(0x02,0x08);
readRegister(0x02);
delay(1000);
}
if(Serial.available()){
int rcmd = (int)Serial.read();
if(rcmd==0x31){
readRegister(0x02);
}
if(rcmd==0x30){
writeRegister(0x02,0x08);
}
}
}

unsigned int readRegister(byte Register ) {
byte HdataToSend = 0x80,LdataToSend = 0x00,HdataToRead = 0x00,LdataToRead = 0x00;
// bit 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
// R=1/W=0 |-Raddr--| |-----------Data---------------------|
// Fault=1/0 |-Raddr--| |-----------Data---------------------|
HdataToSend = HdataToSend | Register << 3;
Serial.print("Sending read command: ");
Serial.print(HdataToSend,HEX);Serial.print(" ");Serial.println(LdataToSend,HEX);
digitalWrite(chipSelectPin, LOW);
SPI.transfer(HdataToSend);
SPI.transfer(LdataToSend);
digitalWrite(chipSelectPin, HIGH);
digitalWrite(chipSelectPin, LOW);
HdataToRead = SPI.transfer(0x00);
LdataToRead = SPI.transfer(0x00);
digitalWrite(chipSelectPin, HIGH);
Hcheck3PWM = HdataToRead;
Lcheck3PWM = LdataToRead;
Serial.print(HdataToRead,HEX); Serial.print(" ");Serial.println(LdataToRead,HEX);

}

void writeRegister(byte Register, byte Value) {
byte HdataToSend = 0x00,LdataToSend = 0x00,HdataToRead = 0x00,LdataToRead = 0x00;
// bit 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
// R=1/W=0 |-Raddr--| |-----------Data---------------------|
HdataToSend = HdataToSend | Register <<3 ;
LdataToSend = Value;
Serial.print("Sending write command: ");
Serial.print(HdataToSend,HEX); Serial.println(LdataToSend,HEX);
digitalWrite(chipSelectPin, LOW);
SPI.transfer(HdataToSend);
SPI.transfer(LdataToSend);
digitalWrite(chipSelectPin, HIGH);
Serial.print(HdataToRead,HEX); Serial.print(" ");Serial.println(LdataToRead,HEX);
}

void runPWM() {
delay(1000);

pinMode(HpinA,OUTPUT);
pinMode(LpinA,OUTPUT);
pinMode(HpinB,OUTPUT);
pinMode(LpinB,OUTPUT);
pinMode(HpinC,OUTPUT);
pinMode(LpinC,OUTPUT);

analogWrite(HpinA,200);
analogWrite(LpinA,50);
analogWrite(HpinB,100);
analogWrite(LpinB,100);
analogWrite(HpinC,100);
analogWrite(HpinC,100);

}

Hi Rick,

Upper half shows actual signal and lower half shows zoom in signal,

Without PWM input,

  First signal is input at INH_A

 Second signal is output at GH_A

With PWM

Hi Rick,

              I have posted screen shot of CRO captures of the PWM outputs. Please review those captures and provide insight on what is possibly going wrong?