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DRV2624: Voltage time pair data format in RAM

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Replies: 2

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Part Number: DRV2624

Hi,

Is the 7-bit voltage value used in the voltage-time pair for waveform creation interpreted as a 7-bit signed value? Thus 0x3F would be max positive voltage and 0x41 would be the max negative voltage. 

Section 8.6.9.2.2 mentions: "Data is stored as interleaved voltage-time pairs. Voltage in the voltage-time pair is a 7-bit signed number with range –63 to 63 when in signed data format, and a 7-bit unsigned number with a range of 0 to 127 when in unsigned data format. The MSB of the voltage byte is reserved for the linear ramping mode."

In previous sections of the datasheet, it mentions negative values are interpreted as braking (180-degrees out of phase for LRA, or reverse direction for ERM).

1. Why would you ever interpret this value as unsigned?

2. Do you need to set this interpretation as signed or unsigned anywhere?

Thanks,

Neal

  • Hi, Neal,

    I'm searching for more information about this. I will answer you in few moments.

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodriguez S.:

    Hi, Neal,

    It seems that there's a typo in the datasheet regarding this. The waveform storage in the integrated RAM is supported for a signed format. Actually, there's no register associated to this. As you mentioned, the data range would go from –63 to 63, interpreted as 180 degree phase for LRA and reverse direction for ERM when negative value is used.

    Thank you for your observation, we will work to have this corrected and avoid future confusions.

    Please let us know if you have additional questions or comments on this.

    Best regards,
    Luis Fernando Rodríguez S.

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