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data projector (U206 - TI DLP 0.2"WVGA DMD) temperature reading

Ivo Strasil
Prodigy 50 points

Hello,

we are resolving a problem with the data projector (U206 - TI DLP 0.2"WVGA DMD) temperature reading. We already obtained a new firmware with a LUT for the resistance to a temperature conversion however the data we are reading out is clearly not the temperature in degrees of Celsius. We disassembled the projector, placed a known NTC thermistor next to the original one, and tried to measure values simultaneously.

Please see the attachment "Temperature measurement testing"  and help us to interpret the reading or find a problem.

Thank you!

Communication with TI support regarding temperature reading on PDB (1).pdfTemperature measurement testing.pdf

  • 0
    TI__Genius 12785 points

    Hello User,

    Welcome back to the E2E forum!

    After attempting to decode this, I cannot yet make sense of the chart you have provided.

    Have you switched the endianness of the hex data? What does the read temperature command and data appear in its most raw form?

    The Read System Temperature command (D6h) typically returns the data in the following format:

    Byte 1 - LSByte

    Byte 2 - MSByte

    Bit 11 (using cardinal numbering) returns the sign (positive or negative) of the temperature. Bits 0 through 10 should return the temperature in Celsius multiplied by 10. For example, if b(11:0) = 100110101010, -426 in decimal is returned. This would indicate -42.6 degrees C.

    It may be that the LUTs that have been implemented for your firmware have some incorrect values. This is the only way that might explain the non-linear data that you are receiving unless I am misinterpreting your data.

    Regards,

    Austin