UM2095

Circuit description

DocID029570 Rev 1

9/11

4

Circuit description

solution for a three-phase BLDC motor in very low consumption mode.

The device is protected against overload and short-circuits: short to ground, short to motor

supply voltage, short between the outputs. If one of the failure events occurs, the fault

signal is set and the fault LED D5 is lit (red).

The STSPIN230 is compatible with single shunt current sense measurement. The current

feedback signal conditioning is performed by hardware available on the board and sent to

the STM32 Nucleo board through the CN7 ST morpho connector (pin 28).

Motor speed regulation can be performed by hardware, by acting on trimmer R12. In this

way, you can change the reference used by STM32 firmware for speed regulation.

The X-NUCLEO-IHM11M1 expansion board provides two hardware solutions for motor

position feedback: one based on sensors and the other one based on sensorless detection.

4.1

Hall/encoder motor speed sensor

The X-NUCLEO-IHM11M1 expansion board implements the Hall/encoder sensor detection

circuit for motor speed feedback. The motor sensor feedback is connected through the J3

connector and an analog circuit to the STM32 Nucleo board in order to detect the motor

rotation.

For sensors requiring external pull-

up, three 10 kΩ resistors are already mounted and

connected to the VDD voltage (if these are not necessary, you can remove them).

The J4 jumper (closed by default) protects the Hall’s input lines connecting them to VDD

voltage through a small-signal Schottky diode.

4.2

Sensorless detection

In six-step driving mode, one of the three phases is left in high impedance state: comparing

this phase voltage with the center-tap voltage, we can detect the BEMF zero-crossing.

This signal is acquired through an analog circuit embedded on the expansion board and

sent to the STM32 Nucleo board through the ST morpho connectors.

For each different STM32 Nucleo development board, the BEFM3 driver input can be

selected through a dedicated resistor, as indicated in the table below.

Table 3: BEFM3 input selection

Nucleo board

CN10 connector

R15

R16

Remark

NUCLEO-F401RE

NUCLEO-F030R8

NUCLEO-L053R8

pin15

0 Ω

Not mounted

Default

NUCLEO-F334R8

pin 26

Not mounted

0 Ω

4.3

Bus voltage circuit

The X-NUCLEO-IHM11M1 expansion board provides the hardware bus voltage sensing.

This signal is acquired with a resistor divider from the motor supply voltage (VBUS) and

sent to the analog to digital converter (connector CN7 pin 30).