HI, I'm using a shield ihm13a1 with nucleo G431RB and DC motor, but I can't regulate the Vref, If I set a Vref = 1,6 (50% d.c) the motor doesn't move, I have set 80% d.c. to make it move. Any idea?

[SMarm.1]

https://www.amazon.it/DealMux-Motoriduttore-encoder-Rapporto-trasmissione/dp/B07Y72T5BJ?pd_rd_w=hZaC3&pf_rd_p=b928db63-55ee-49e1-8ca9-807c91a11a4c&pf_rd_r=FMAZFZZ865BW326H55X9&pd_rd_r=c08f27cc-b043-4ac6-bd73-a3924ed21699&pd_rd_wg=8qSBw&pd_rd_i=B07Y72T5BJ&psc=1&ref_=pd_bap_d_rp_15_t

[Cristiana SCARAMEL]

Hello @SMarm.1​,

the REF pin is the reference voltage for the current limiter circuitry, its recommended value is up to 0.5V (pay attention the absolute maximum ratings is 1 V!).

This voltage is used to limit the motor current it is not related to the motor speed.

The outputs of the full-bridge are controlled by the PWM and PH inputs, refer to STSPIN250 datasheet for details.

Which is your supply voltage? From your link it seems that the motor needs at least 6V to run.

Anyway, the X-NUCLEO-IHM13A1 expansion board offers native support for a selection of Nucleo development boards (NUCLEO-F401RE, NUCLEO-F334R8, NUCLEO-F030R8, NUCLEO-L053R8).

You are using NUCLEO-G431RB, you developed your own software to drive the DC motor?

As first step you checked the correct Vref connection with Arduino connector according to your software.

The reference voltage for the current limiter circuitry of the STSPIN250 can be selected through dedicated resistors (R17 and R20). The board allow the connection to CN8 pin1 or alternatively to CN5 pin1 trough refer to board schematic.

Let me know if these info are useful to run the motor.

[Cristiana SCARAMEL]

Hello @SMarm.1​ are there any updates on your issue?

[SMarm.1]

Thanks for the answer.

Yes, I'm using G431RB setting all peripheral like F401 and it works vary well. However, the problem with Vref doesn't change. I set, for example, 9V for voltage supply and Vref with PWM 100 kHz and D.C. at least 70% , the motor works but when PWM motor reachs 70% the DC motor saturates. The attached maybe is more clear to understand the situation. In the picture 2500 means 100% D.C.

[Cristiana SCARAMEL]

Hi @SMarm.1​,

what do you mean with "when PWM motor reaches 70% the DC motor saturates"?

If you mean that the current does not increase as the voltage increases, could be due to the system physical limits.

Even if you increase the Vref value the maximum motor current is limited by the effects of the BEMF and the motor windings resistance.

A numeric example, in your case (DC 70%) the max target current can be calculated as:

Vref = 0.7 * 3.3 V * (47 kohm / 247 kohm) = 0.44 V

Itarget = 0.44 V / 0.34 ohm = 1.29 A

The resulting current is limited by the abovementioned effects.

Let me know if these info are useful to you, if so please "Select as Best" button to close the topic.