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LP8543 initialization example

Sam Porter
Prodigy 190 points
Other Parts Discussed in Thread: LP8543

Hi,

I was wondering if someone could point me to an example initialization of the LP8543 LED chip.  I would like to incorporate this part in an embedded system running linux, but have not been able to locate a driver or other info aside from the LP8543 datasheet which might help guide me through its setup.

Thanks.

Sam

  • 0
    TI__Intellectual 2510 points

    Hi Sam,

    Unfortunately at the moment there is no documentation online other than the datasheet. Are you going to control the device with I2C or SMBus or using it as a stand-alone?

    Regards,

    Sami

  • 0 in reply to Sami Kotijarvi
    Prodigy 190 points

    Sami, Thanks for the reply.  The LP8543 will be controlled by I2C.

    Sam

  • 0 in reply to Sam Porter
    TI__Intellectual 2510 points

    Sam,

    Here is one example:

    I2C register for brightness control, LED current set with register, ambient light compensation enabled

    Address    Data       Function
    00H           1DH        PWM value for Display1 is set to 11.4%.

    09H           0FH        Set LED current value to be read from the register. ALS state set with register, ALS calculator enabled, ALS enabled. ALSO polarity set with EEPROM bit <ALSO_POLARITY>, default = normal polarity.

    05H           1EH         Sets current for Display1 to 7.06 mA

    01H            05H        Chip will start up with boost converter in adaptive mode. Start voltage for boost is loaded from EEPROM register (default 38V). Backlight control is enabled. PSPWM mode is set with EEPROM. Display1 activates with 7.06 mA current and with 11.4%

    Regards,

    Sami

  • 0 in reply to Sami Kotijarvi
    Prodigy 190 points

    Sami,

    Thank you for the example.  For my application I will be using Display 2, but without ALS.  So adapting your example, I would do:

    Address  Data    Function

    08H          1DH    Set Display 2 at 11.4%

    09H           08H    Read LED current from register,  ALS disabled.

    06H           1EH    Set Display 2 current to 7.06 mA.

    Question--With ALS disabled, does ALS_SEL bit (D2) of Config2 register become a "don't care"?

    Thanks,

    Sam

  • 0 in reply to Sam Porter
    TI__Intellectual 2510 points

    Sam,

    Sorry for the delay in response.

    When the ALS_SEL bit in Config register2 (0x09) is set to 0 ALS state is set with the ALS_EN bit in EEPROM (address 0xB2). By default this bit is 0, so the ALS is disabled.

    When the ALS_SEL bit in Config register2 (0x09) is set to 1 ALS state is set with the ALS_EN bit in register 0x09.

    Thanks,

    Sami