Recently, i am using the lm3s3739 to develop the usb host mode, to connect the usb disk. the system generate the VBUS ERR, the schematic hasn't protect component and the tps2501 pwr manage, i only use the boost component to supply the +5 VBUS, pull-up PB1 to VBUS, pull down the PB0 to GND with 10 Ohm resistance, keep the USB-EPE, PFLT not connect, In the software, ignore the PFLT, according to the errata, fix the hardware bug when the system generate the VBUS ERROR, reset the USB0 and reinitial the usb device. but it can't escape the VBUS error. why ? who can give me some idea?
Is this a custom board or an evaluation kit? Please send us the date code on the third line of the device marking. Also, please send us the USB clock setting.
Sean de la Haye
Thanks for you replies,
Stellaris SeanIs this a custom board or an evaluation kit?
It is custom board,
Stellaris Seanthe date code on the third line of the device marking
The third line is "S9-04P006H" , the whole marking is "LM3S3739 IQC50A0 SD S9-04P006H"
Stellaris Seanthe USB clock setting.
I can't find the code about usb clock setting, the below code is the system clock and usb pll setting. the all about usb host is the same as lm3s3748 evaluation kit's code.
The system clock setting (the hardware crystal is 8Mhz). :
"SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN | SYSCTL_XTAL_8MHZ);"
the usb clock setting is:
MAP_SysCtlPeripheralReset(SYSCTL_PERIPH_USB0); MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_USB0); MAP_SysCtlUSBPLLEnable();
From your description, it sounds like you are not having any problems with the clocking errata. I talked with one of the USB experts here and they recommended removing your pullup to VBUS on PB1 (Replace it with a 0 Ohm resistor or short the connection). They have told me that if you connected a oscilloscope on the pin side of the resistor, you would see the voltage droop by ~0.3V when you connect. The resistor is causing enough of a power draw that when you connect it is going below the 4.7V lower limit.
I have connected the PB1 to VBUS with 0 Ohm resistor, The VBUS voltage can reach the 4.97v , and the rise time is 380us. The system has generate the VBUS ERROR before connect the usb disk.
My colleague has suggested that you try driving 5V on PB1 before the device is powered up. He said that this is a requirement listed in section 12.3 in the LM3S3739 errata document.
I have a test according your advice, driving +5V on PB1 before the device is powered up, and connect PB0 to GND through 0 Ohm resistor, But the methods can't resolve the problem. In the key, some is ok among our productions, i have some switch test,but the vbus error follow the lm3s3739.
This problem is related to the version and code date of the chip? I have test two pcb with "LM3S3739-IQC50A0-$9-06P048",the both can't work on usb host, then , test two pcb with "lm3s3739-ICQ50A0-$9-21P072H", the both work well?
Thank you for the information on the part numbers -- this should help the debug. I will consult my colleagues and see if there are any other ideas.
I have talked with my colleagues and we can only conclude that the parts with the LM3S3739-IQC50A0-$9-06P048 date code are damaged. The next step is to contact your local TI Sales office to get them replaced with the parts with the newer date code. It was also recommended that a 4.7 Ohm resistor be connected between the +5V and PB1.
Thanks a lot, Do you mean the chips is okay, only damaged in using ? To say simply, I only want to know what result in the problem, and how to avoid it. your advice adding 4.7 ohm resistor i will have a test, but to get the effect it isn't a short time.
They are most likely defective if you have newer devices that are functioning correctly. Since the newer devices you have are working, our feeling is that the replacement chips should also work.
Sorry, I probably did not describe clearly. In all products using "LM3S3739-IQC50A0-$9-06P048H', most of it is normal.There is a small part of products is not working properly. but We still have a lot of inventory,and not only the date code. if we apply replacement, We must spend long time in the test. All of these will affect the progress of our products. Oh , My GOD!
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