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CCS/RM48L952: USB Device Not working

V Kishore
Prodigy 200 points

Part Number: RM48L952
Other Parts Discussed in Thread: HALCOGEN, TUSB1105, TUSB1106

Tool/software: Code Composer Studio

Dear sir,

I'm working in Evaluation board (Hercules safety MCU Development kit RM4 MCU) in this, I have generated USB device CDC code from HALCOGEN SOFTWARE and its working fine(part number RM48L952).

The same controller i'm using in custom board , I have loaded the code into my board here its not working (pop up message is : USB device not recognized). and some changes are there in hardware design check out below E3 pin its not connected (here my requirement is to prove without Vbus):  

 

Fig ; 1- custom board design

and please checkout my EVB board design:

Fig ; 2- EVB design

here E3 pin is connected to USB Female type-B connector;

the same code without any modifications i have loaded into my custom board, its not working. but in my design there is no jack like Female USB  type-B connector. please check design below:

Fig ; 3- custom board USB design 

here Pullup D+ is connected and Host related resisters are removed: (i mean High speed and Device configuration)

For trial i just connected E3 pin to USB 5V pin (GND also connected) even though it is not working.

Signals I measured in custom board:

Suspend ; by default its is coming High .. but in EVB its Low so i forcefully grounded. (Is it right way??)

Softcon : High

Speed : High

D+: High

D- ; low

Please help us regarding:

1. Can we prove USB without VBUS and GND (Only with D+ and D-)?

2. Is Vendor ID and Product ID are Important from EVB board to Custom Board?

3. is it work without Female USB type B jack (Connector) ? ...(I mean direct connections .... Upstream is connected to Computer .. down stream is connected to board like pin connections(No Jack) two wires D+ and D-)

4. This code is for Bus Powered transfer ( Should i need to change to self powered because there is no VBUS connections)?

5. should i need to modify any code ?

Thanking You,

best regards,

V Kishore.

  • 0
    TI__Guru**** 201116 points

    Hello,

    At the device end, a 1.5 kohm resistor pulls one of the data lines (D+, or D-) up to a 3.3V which might be derived from VBUS. The pull-up resistor is on D- for a low speed device, and on D+ for a full speed device. The host can determine the required speed by observing which line is pulled high. If the 3.3V is not driven from VBUS, you can ignore the VBUS. But the GND should be used as a reference between boards. The USB function controller on RM4x devices only supports implementation as a full-speed USB device. As such, the pullup resistor must be connected to the D+ signal to indicate implementation of a full-speed USB device. Does your board have this resistor?

    VID and PID are required to distinguish different devices from one to other. VID is allocated by the USB organization at some fees. For development of a prototype you need not have a unique VID/PID.

    The data is transferred through the D+ and D- lines with 90ohms differential impedance, and two lines should be twisted and have the same length. I suggest to use a standard USB cable.

    I don't think you need to modify code for your board.

  • 0 in reply to QJ Wang
    Prodigy 200 points

    Hi,

    Thank you for your reply,

    Does your board have this resistor?......... Yes, it is implemented.

    The difference from Evaluation board to custom board is USB Phy part number, in Evaluation board  USB we used tusb1105 and in Custom board  we used tusb1106.

    And the exact difference is, In evaluation board (tusb1105) Mode Pin is grounded which means it is working in Single Ended, But in tusb1106 there is no Mode Pin and tusb1106 supports only differential ended.

    Here I was stucked, I'm not  getting where to change in hardware or software.

    I did not get anything about single ended and differential ended in software code. and same as in hardware also.

    Please help me to figure out this problem.

    For your reference controller Part number : RM48L952

    Thanks,

    V Kishore 

     

  • 0 in reply to V Kishore
    TI__Guru**** 201116 points

    Hello Kishore,

    The USB device module doesn't support differential mode of operation for the transceiver interface.