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TPS2546EVM-064: TPS2546 CDP Mode @ stand alone Mode

Part Number: TPS2546EVM-064

Hi Team,

We connected the Vuzix M300 to the TPS 2546 evalkit.
Power Supply connected to 5V, EN Jumper is plugged in (TPS is disable)
Ctrl1 to 3 no Jumper plugged in (@ Datasheet Table 3 CDP Mode)
 
After startup the Vuzix we enable the TPS via Jumper. We get this D/N and D/P Signals.
The D/N Signal after startup is alwalys high and the handshake isn´t well done.
We use it in a stand alone operation.
The DM-OUT ist always low.
What do we wrong?
Later we would like to use a STM32F205 MCU.The STM only Support SDP (500mA) USB 2.0. Is it possible to charge with the TPS2546 in CDP with 1500mA in this configuration? 
The Support from Vuzix tell us: Regarding the battery question, the quick answer
is that the M300 can support SDP, CDP and DCP.
Many Thanks.
Greets
Thorsten Bursche
  • Hi Thorsten,

    Have you tried charging the Vuzix M300 in DCP auto mode? It doesn't look like the Vuzix is doing primary or secondary detection just USB2.0 Enumeration. Could you probe the current on VBUS and send me scope captures for CDP and DCP Auto mode?

    Just to be clear, Vuzix says that they support charging from a BC1.2 source whether CDP or DCP correct?

    I believe using the STM32F205 should work fine. All the MCU does is communicate over the USB2.0 data lines so the charging current shouldn't effect it as there is a supply for the 1.5A on VBUS. The TPS2546 takes care of the initial CDP handshake then the data lines are available for the MCU to use. Note that the data lines are switched on even while the TPS2546 does the CDP handshake.

    Regards,
    Donovan
  • In reply to Donovan Porter:

    Hi Donovan,

    Thank for your quickly reply.

    I tried all jumper settings, but i only get the 500mA.

    Today i ask Vuzix again for the B1.2. I await a reply.

    You said:

    Note that the data lines are switched on even while the TPS2546 does the CDP handshake.  What does it mean? The STM is set by software to SDP with 21K pull down on the D+ and D-. 

    Vuzix_TPS_CDP.bmp

     

    Vuzix_TPS_DCP-Auto.bmp

    Regards,

    Thorsten

  • In reply to Thorsten Bursche:

    Hi Thorsten,

    Thanks for the scope captures.  It doesn't seem like the Vuzix is doing BC1.2 detection.  Please let me know what they say.

    Page 27 of the TPS2546 datasheet section 8.4.3 explains what I was saying about the internal mux being switched on even when the TPS2546 is in CDP mode.

    I do not think this will be an issue.  The 21k ohm the STM datasheet recommends is for detecting USB2.0 speed of the device connected.

    Regards,

    Donovan

  • In reply to Donovan Porter:

    Hi Donovan,

    we still waiting on an answser from Vuzix about the charging mode.....

    we figured out that it depend on the usb cable...... We changed from a no name usb cable to the "Vuzix" cable and we get more than 500mA charge current. So the stand alone mode is fine.

    Now we connected the customer PCB with the stm to the TPS with the Vuzix. The current is ok (we charge the Vuzix before) but no data communication.

    We scope the Start Up via Enable the TPS:

     

    Without the TPS we scope this: SDP Mode 

    Do you have an idear what we are doing wrong?

    Thx

    Regards,

    Thorsten

  • In reply to Thorsten Bursche:

    Hi Thorsten,

    The first scope capture is when the TPS2546 is in CDP mode correct?
    The second scope capture is without the TPS2546 at all and just the port connected to the STM controller?

    Could you try again in DCP Shorted mode and in SDP1 mode please?

    It almost seems as if the Vuzix is determining it is connected to a charging port and therefore not communicating data.

    Regards,
    Donovan
  • In reply to Donovan Porter:

    Hi Donovan,
    we solved our issue. I depend on some software timings.
    Now we get 700mA in CDP Mode and the usb communikation.
    Thanks for your support,
    Regards,
    Thorsten
  • In reply to Thorsten Bursche:

    Hi Thorsten,

    Awesome!  Glad you guys got it working.

    Regards,

    Donovan

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