Background: We are working with LM3S5B91-C3 processor to connect its USB to SMSC's USB2512 hub. The hub will be used to connect keyboard.
Processor Details: LM3S5B91-IQC80C3XD $A-12B075H. Clock Speed: 20MHz.
Issue: When the board was initially designed, we had no issues in USB Hub connection. At times, the connected keyboard did not work, but multiple power-cycling made it work. Now we are observing that all our production boards, having same hardware design and software drivers, are behaving differently in regards to USB hub connectivity.
1. Some boards are working (10%)2. Some boards are freezing during USB enumeration process. Enumeration does not detect the hub. (15%)3. Some boards are freezing during USBGetDescriptor and USBGetConfigDescriptor. The control is waiting for the endpoint-0 to become idle. This never happens. (60%)4. Some boards complete the initialization, the connected devices (keyboard) does not work at all (15%)
The process is working at 20Mhz clock frequency. We tried changing the frequency to 22Mhz, 25Mhz, 30Mhz, 40Mhz and 50Mhz after reading some online blogs. This made some boards to work at 30Mhz but it was not consistent; most of the boards (60%) are still not working. Is this something due to the LM3S5B91-C3 USB errata? How is changing the clock frequency affecting the USB working and interrupt timings? Hub works fine when connect to a Windows PC.
Additionally, we are unable to use JTAG debugger on this USB app due to Errata 2.3 (Rev K). Not sure how we are suppose to use the workaround? We are currently using UART to debug and check the program flow. In all cases the processor freezes - waiting for EP0 to become idle or some interrupt.
We found following links which are similar to our issues but for different processor:http://e2e.ti.com/support/microcontrollers/stellaris_arm_cortex-m3_microcontroller/f/471/t/51772.aspx?PageIndex=1http://e2e.ti.com/support/microcontrollers/stellaris_arm_cortex-m3_microcontroller/f/471/t/171341.aspx
Could anyone help us in resolving this critical issue? If there are more details required, please feel free to ask. Looking forward to get some response. Any help in this regards will be appreciated.
Due to erratum, " 11.5 Cannot communicate with a low-speed Device through a hub," the minimum speed for the USB controller is 30 MHz. You also can't connect to low-speed Devices through a hub unless you have parts with date codes of 0x1A (October 2011) or later. If you change your system clock, I suspect your problems will as well.
We tested our system with C5 with date codes of 0x1A. That resolves our Keyboard-Hub communication problems. Thank you!
Could you also guide us on how to use JTag debugger for debugging the USB. When in the debug mode, USB enumeration fails and it never recognizes that a HUB is connected to it as device. Works fine in the release mode.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.