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LM5066: Getting 0xFF for all messages on the i2c bus

Prodigy 30 points

Replies: 4

Views: 154

Part Number: LM5066

Hello,

I always receive 0xFF bytes from the device. No matter what the read function is. I tried with MFR_ID (99h), READ_VIN(88h), READ_VOUT(8Bh) and READ_TEMPERATURE(8Dh).

The device answers me with acknowledges but data(s) is(are) FF in all the cases.

The analog part of the device seems to work normally.

Here after are two captures of the communication I have with the board for 88h and 8Bh functions. I assume I miss something because I changed the device and the problem still remains.

Note that SDAI and SDAO are connected on my board.

Thanks in advance for you help,

Maxime Javaux

  • Guru 53615 points

    Hi Maxime,

    Welcome to E2E!

    It looks the problem you faced is similar to the one discussed in the thread https://e2e.ti.com/support/sensors/f/1023/t/722669?HDC2010-HDC2010-I2C-data-out-is-00-FF-FF-FF-not-seem-to-get-proper-ACK-from-HDC2010. Can you try and let me know if it does not help.

    Best Regards, Rakesh

    --------------------------------------------------------------------------------------------------------

    To find the latest information on Power Switches, Visit www.ti.com/powerswitch 

  • In reply to Rakesh:

    Hello Rakesh,

    I have a write first with the command and then, a read with all the FF. Here is the data:

    Here is the scope capture:

    I think it is what I have to do when I look at the Thread you link before or not ?

    Regards

  • Guru 53615 points

    In reply to Javaux Maxime:

    Hi Maxime,

    Do you have FTDI-dongle which comes with our EVM ? Can you connect FTDI dongle with hot-swap GUI and try communicating with our device. ?

    Best Regards, Rakesh

    --------------------------------------------------------------------------------------------------------

    To find the latest information on Power Switches, Visit www.ti.com/powerswitch 

  • In reply to Rakesh:

    Hello,

    I found my error. I implemented the PMBus protocol based on the INA233 chip that I use too and in that datasheet, the protocol for a read word is described as:

    Because of that, I implemented the protocol so that there is a stop condition between the two i2c messages from the master but that is not the way it has to ! There should not be a stop in between both messages. Because of that, the LM5066 is just lost and do not give any answers (Leading to FFFF because it releases the bus).

    Regards,

    Max

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