Doubt with a schematic. Detecting the BEMF.

[joelsrf]

Can anyone help me with the schematic part of the BEMF voltage divider? Thanks. What do you think A0, A1, A2 and D6 are doing? I think that D6 detects when it´s a 0 crosing and A0, A1, A2 detect during all the time if they´re floating or if they are active phases. So then, knowing with phase is floating and knowing how the other two phases are, we can know wich is the next step sequence.

[Doctorandus_P]

R13, R16, R17 are the top side and R12, R14, R15 are the bottom side of a voltage divider to get the motor voltage into the range of the ADC.

R20, R21, R22 take the average of the three motor phase voltages, and they mimic the "star" point of the motor

The microcontroller can now compare the phase voltages (A0, A1, A2) with the "star point (D6) to get very close to the zero crossing.

ATMEGA328 has an analog comparator. Is this comparator connected to D6 (and configurable to have any of the analog inputs for the other side?

[Picuino]

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