Drive Strength

  • Hello,


    Is it possible to set the drive strength for UART and GPIO (OS is WEC2013)?

    According the driver documentation the registry value DrvStrength can be used to set drive strength for I2C and SPI, but there is no such a registry key for UART and GPIO.


    Best regards,

    Christian

  • Hello,


    DIO: i am not a HW GUI, please correct me if i am wrong, but i assume due to the low frequency (i expect about max. 20kHz using ReadFile/WriteFile and a bit more using IOCTLs) this feature is not relevant for this driver. Overtones in double-digit kHz range may have very small amplitudes. In other words the feature is not implemented untli now.


    UART: you can specify "DriveStrength":

    Default (-1) -> 40 Ohm

    0 or 1 -> 240 Ohm

    else 34 Ohm

    F&S Elektronik Systeme GmbH
    As this is an international forum, please try to post in English.
    Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.

  • I'm also no hardware expert, but to my knowledge the drive strength has influence on the shape of the edges, rather independent from the frequency, at least as long as the signal reaches a stable high or low level. Our hardware department just asked me if it is possible to change the drive strength of I2C, SPI, UART and GPIO signals. I have learned that it is possible for I2C, SPI and UART, for GPIO not. I check with my colleagues if they have a problem with the drive strength for GPIO signals or if they just want to make some cosmetic fine tunings.


    By the way, what is the registry value for the drive strength of the UART signals? In your comment above you wrote "DriveStrength", but for I2C, LCD, SPI it is "DrvStrength".

  • Hello,


    "DriveStrength" is correct for UART.


    Above i talk about the frequency because EMV. As far as i know some customers use drive strenght value to reduce EMV caused by display. Malformed shapes have additional high frequncy overtones.

    F&S Elektronik Systeme GmbH
    As this is an international forum, please try to post in English.
    Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.