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DS90UH948-Q1: About 0x59 and 0xA2 registers and rate configuration

Hale Tan
Expert 3770 points

Part Number: DS90UH948-Q1

Hi team,

1. About 0x59 and 0xA2 registers, I don't see it in the DS, but reading that these two registers have values, what's the meaning of 0x59 and 0xA2 registers? Could you introduce it in details?
2. About 948 I2C rate configuration, SCL default value is 0x83 and 0x84, measured rate only 73khz. What should I do if I want to configure a 400khz?

  • 0
    TI__Guru 67510 points

    Hale, 

    0x59, 0xA2, and many other registers for that matter are non-public registers and values are proprietary to the internals of the device. Customer should not modify.

    Hale Tan said:
    2. About 948 I2C rate configuration, SCL default value is 0x83 and 0x84, measured rate only 73khz. What should I do if I want to configure a 400khz?

    SCL low/high are calculated based on the AON clock and the equation in those registers. The AON clock is fairly inaccurate, which is why you see a slightly different value than programmed. 

    Registers 0x88 and 0x89 control the SCL time based on the equation below.

    Edit: Removed incorrect equation

    Regards, 

    Logan

  • 0 in reply to Logan Cummins
    TI__Expert 3770 points

    Hi Logan,

    Thanks.

    But I didn't find 0x88 in the datasheet as below. Could you tell me what register should I configure, if I want to configure a 400kHz? 0x83 and 0x84 or 0x88 and 0x89? What value should I set?

  • 0 in reply to Hale Tan
    TI__Guru 67510 points

    Hi Hale, 

    Sorry, typo before. It is 0x26 and 0x27 for 948. 

    Convert 400kHz to high/low time: 1250ns

    Divide high/low time by 50ns: 25 

    Convert 25dec to hex: 0x19

    Write 0x19 to 0x26/0x27.

    Regards, 

    Logan