Unable to use the EVAL6235Q alone or with the STEVAL-PCC009V2

[KSmit.3]

Description:

This is what we did with the EVAL6235Q to use the external speed loop connector to drive a BLDC motor:

1.      On the power supply connector, we attached 12 V.

2.      We connected our BLDC motor to the 3ph BLDC motor connector.

3.      We connected our BLDC motor hall effect sensors to connector J7 pins H1, H2, and H3.

4.      We connected our BLDC motor power pins to connector J7 pins Vdd and GND.

5.      We connected J6 pin 2 and 3 together.

6.      We connected a 3.3 V, PWM (and varied the frequency between 1 to 100 kHz) from a function generator to J8 pin 3 (slout).

After doing the steps 1 to 6 above, the motor would not turn and if we watched the voltage on connector J5 pins OUT 1, OUT 2, OUT3, the voltage was always zero.

Are we doing something wrong or is there a problem with our EVAL6235Q?

This is what we did to try and get the STEVAL-PCC009V2 to work:

We purchased an STEVAL-PCC009V2 (IBU universal interface based on the STM32x) board because it was recommended to be used with the EVAL6235Q board. However, the drivers for this board are written to be used with Window XP or 2000. Our PCs are running Windows 10. In the documentation, it says that when the STEVAL board is connected to the PC that a Window will pop up to walk through installing the drivers. However, this does not happen. Also, after it is connected to the USB port and we open Device Manager and expand the “Universal Serial Bus controllers�?, the “STM32 based IBU UI Tool�? is not shown. The user manual says to contact technical support if this happens.

How should we proceed? Do you have Window 10 drivers? Or do you have an newer communication board?

[Cristiana SCARAMEL]

Hello @KSmit.3​ and welcome to the ST Community.

Some comments:

How did you set the others L6235Q input pins?

By default:

EN is low (pull-down) --> power stage in High Impedance

BRAKE is low (pull-down) --> brake status (HS on)

We connected a 3.3 V, PWM (and varied the frequency between 1 to 100 kHz) from a function generator to J8 pin 3 (slout).

The SLOUT signal is connected to L6235Q through the VREF pin, but this signal must be voltage level (not a PWM).

The connector J8 has been design to make the signals available to implement one external speed loop.(un example of analog speed loop is shown in the L6235Q datasheet figure 17).

Concerning the connection with STEVAL-PCC009V2, did you download the STSW-SPIN003 software and tried to connect the systems?

It is possible the the PC do not "see" the COM port but the system work properly.

Let me know you progress

[KChu.1]

Hello @Cristiana SCARAMEL​ ,

Thanks for the reply.

We set the EN pin to high (5V), and grounded the BRAKE and FW/CCW pins.

Since the SLOUT cannot be a PWM, if we want to control the motor with a PWM signal, should we connect it directly to Vref, which is pin 11 of J3?

As for the STEVAL-PCC009V2. We downloaded the software but would not connect to the board. We tried to install a driver but the driver installer window would not come up.

[Cristiana SCARAMEL]

Hello @KChu.1​ ,

the BRAKE pin if not used must be connected to '5V', if low the device is in brake status (all high-side power MOSFETs on).

If you apply the PWM signal to J3-11, with J6 closed between 1-2, you can low pass filter the signal through R6/R8/C9.

Assuming that the PWM output swings from 0 to 5 V, the resulting Vref is proportional to the PWM Duty cycle:

Vref = (5 V x D x R8) / (R6 + R8)

As for the STEVAL-PCC009V2, I can suggest to update the MCU firmware using the ST-LINK/V2 programmer or an equivalent tool.

You need the STM32CubeProgrammer software and the board firmware STSW-PCC009V2FW

[KChu.1]

Thanks again for the reply!

We set the BRAKE to 5V and sent in the PWM signal to J3-11. The motor started making sound and tried to move. But it stalled like it didn’t know which direction to spin. We checked OUT1-3 and found that they are all high (12V). From the hall sensor table in the L6235Q data sheet, we noticed that one of the phases has to be ground level for the motor to spin. Do you have any suggestion or idea as to why the motor driver is giving a high output on all three phases?

For the communication board, we followed your direction and was able to install the driver for the communication board. However, there is still no communication between the STSW-SPIN003 and the board. The software couldn’t detect the device and it had no effect when we change the parameters in the software.

[Cristiana SCARAMEL]

Hi @KChu.1​,

you are right in the 6-step driving you have always one OUT phase 'high', one 'low' and one in High impedance.

The only way to have all three OUT 'high' is BRAKE pin low.

Please check the proper connection of motor phases and Hall sensors (proper sequence 1 / 2 / 3).

Moreover, when you set high the EN pin which is the value of H1, H2 and H3?

And finally, with your PWM which voltage value is applied on the VREF pin?

Keep in mind that the VREF value is the reference value for the current control do not affect the motor speed without external circuitry.

[KChu.1]

Hi @Cristiana SCARAMEL​ ,

We checked the motor phases and hall sensors sequence, and they were correct. The values of the hall sensors are actually changing a little bit as we now realize the motor is not stalled completely. It tries to spin but would change between clockwise and counterclockwise very quickly . The outputs are also not all HIGH at all time, they change slightly when the motor "vibrate".

For the PWM signal, we first tried a 5V but it seemed like it was too high the motor would get hot, so we tuned it down to about 3V. But neither of the values worked.

But we did get something new. Although we still couldn't control the communication board, when we connects it with the motor driver, the motor starts spinning. Since the software is not communicating with the communication board, we probe each of the pins in J3 connecter when the communication board is connected to the motor driver to look at each of their values. We see that BRAKE, Vref, and FW/RW are about 2V, and the EN is 2.5V. We tried putting in the same values to those pins without connecting the communication board, but the motor would not spin. So right now it only spins when we connect the communication board to it.

[Cristiana SCARAMEL]

Hi @KChu.1​ 

The outputs are also not all HIGH at all time, they change slightly when the motor "vibrate".

Could you share some oscilloscope waveforms of the outputs voltage?

For the PWM signal, we first tried a 5V but it seemed like it was too high the motor would get hot, so we tuned it down to about 3V. But neither of the values worked.

With 5V or 3V, are you referring to the 'high' value of PWM?

What is the value of duty cycle (D)?

So basically what is the real value of VREF at the device pin?