SPRABN2A March   2019  – December 2019 AM3352 , AM3354 , AM3356 , AM3357 , AM3358 , AM3358-EP , AM3359

 

  1.   AM335x Schematic Checklist
    1.     Trademarks
    2. 1 Introduction
    3. 2 Recommendations Specific to AM335x
      1. 2.1  Unused Signals
      2. 2.2  SYSBOOT Configuration and Required Termination
      3. 2.3  System Issues
        1. 2.3.1 Pinmux
        2. 2.3.2 Pullups
        3. 2.3.3 General Debug
        4. 2.3.4 Warm Reset
        5. 2.3.5 Peripheral Clocking
      4. 2.4  Low-Power Considerations
      5. 2.5  Clocking
      6. 2.6  General DDR Guidelines
        1. 2.6.1 DDR2
        2. 2.6.2 DDR3
      7. 2.7  MultiMedia Card/ (MMC)
      8. 2.8  Inter-Integrated Circuit (I2C)
      9. 2.9  LCD
      10. 2.10 Power
      11. 2.11 Touchscreen
        1. 2.11.1 If ADC/Touchscreen is not Used
      12. 2.12 USB
        1. 2.12.1 If USB0 or USB1 is not Used
      13. 2.13 External Interrupt (EXTINTn)
      14. 2.14 Ethernet
    4. 3 References
  2.   Revision History

2.12 USB

For more details, see High-speed interface layout guidelines.

The AM335x USB0_ID and USB1_ID terminals should never be connected to any external voltage source. These terminals should be open-circuit when the respective USB port is configured to operate in USB peripheral mode, or should be connected to ground when the respective USB port is configured to operate in USB host mode.

USBx_DP and USB_DM should never have any series resistors or capacitance on these signals. These signals should be straight traces to the connector with no stubs or test points.

Typical connections for a USB peripheral:

  • USBx_DP and USBx_DM are connected directly to the USB connector
  • USBx_CE can be used if supporting charging. This generally would be connected to the enable of a charging source for the battery.
  • USBx_ID can be left unconnected
  • USBx_DRVVBUS is not used and can be left unconnected
  • USBx_VBUS should be connected directly to the VBUS pin on the USB connector

Typical connections for a USB host:

  • USBx_DP and USBx_DM are connected directly to the USB connector
  • USBx_CE is typically not used and can be left unconnected
  • USDx_ID should be grounded
  • USBx_DRVVBUS should be connected to the enable of the 5 V VBUS power source.
  • USBx_VBUS should be connected to the output of the 5 V VBUS power source

Typical connections for a USB host with USB hub:

  • USBx_DP and USBx_DM are connected directly to the USB hub upstream port. The hub then distributes these signals to the downstream ports as needed.
  • USBx_CE is typically not used and can be left unconnected
  • USDx_ID should be grounded to enable host mode.
  • USBx_DRVVBUS should be connected to the enable of the 5 V VBUS power source.
  • USBx_VBUS should be connected to the output of the 5 V VBUS power source. It is also connected to the VBUS detect on the hub, which allows the hub to selectively enable or disable typically through a power switch to each downstream port.