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LMK05318: I2C address question

Part Number: LMK05318

I have begun to have a look at LMK05318 I2C communication. The goal is to store in a memory 8 sets of registers. Then, based, on a input given by the end-user, these values will be written into LMK05318 registers through I2C using a microcontroller.  For now, however, I am using LMK05318EVM in order to power and to program the registers.

The first doubt is about LMK05318 address. According to "LMK05318EVM User's Guide"  (page 16) when S6[1:3] = 001,  the address should be 0x64 . However, when  I issue the command "Scan I2C bus" with TiCS-Pro, the following output is given " Device found at 0x78. Address will be updated"  I have only this EVM connected to the USB and there are no communication issues between TICs Pro and the EVM

Moreover, I have put a logic analyzer in order to observe I2C communication when TICS Pro commands are sent to the EVM. For example I issue the command "write single register" with TicsPro in order to write the register R319 with the value 0x03. The values returned by the logic analyzer are 0xF0 0x01 0x3F 0x03.  Therefore, considering the first byte 0xF0 and the shifting, I guess that LMK05318 7 bit address is 0x78 because after the shifting into 8 bit address this value becomes 0xF0.

What I am missing? Thanks in advance

  • Hi Philip,

    Thanks for posting on E2E. I have assigned your post to the responsible engineer. He will respond to you early next week.

    Kind regards,
    Lane

  • Hello, 

    This is fresh evm that was untouched from the factory? 

    Regards, Amin

  • With respect to the default configuration, I have only disabled the power to the on-board XO. Therefore, pins 2 and 3 of JP17 are connected. This is because I have used an higher frequency accuracy XO. This, however, is not related to I2C configuration.

    As far as I2C is concerned, 

    - The following JP20 pins are connected: 1-2, 3-4,11-12,13-14

    - S9[1:2]=OFF

    - S6[1]=OFF S6[2:3]=ON

    I have loaded different configurations but already from the beginning TICS Pro has found the board at 0x78 address. The EVM was purchased on Digikey in February 2020

  • Hi, 

    This shouldn't be the case... 

    But is loading configuration and/or communicating with the chip any issues with regards to TICSpro? Or once device is found software is perfectly capable of communicating with the silicon with no issues. 

    I suspect somehow the slave address got updated through the GUI (image below) but again that shouldn't have been the case...

    Regards,

    Amin