Hi Team,
I met one issue related with the AM3352 USB1_OCn pin. My customer is using the USB1 as the host mode.
The software they're using is the Starterware 02_00_01_01. The demo they're using the usb_device_host_msc project is under the directory C:\ti\AM335X_StarterWare_02_00_01_01\build\armv7a\cgt_ccs\am335x\beaglebone\usb_device_host_msc.
In their first hardware version, they took the BBB's EVM's design on the USB part as the reference exactly, they used the ZCZ T16 ball(GPIO1_26) as the USB1_OCn pin. It worked well with the USB function.
But in the second version, they removed the TPS2051, connected the VBUS to the 5V input of the board directly, finding the USB1 port could not work properly. Then we measured the USBDRVVBUS, it is low, but not high. According to the datasheet, USBDRVVBUS should be high when working correctly as the host.
We checked this issue very carefully with the first version hardware, if they removed the TPS2051, connecting the VBUS to the 5V system power. It worked well when the USB1_OCn is pulled high with 10K resistor to 3.3V, but failed if the USB1_OCn is left unconnected. The issue observation is similar with the second version board.
So my question is:
1. Is USB1_OCn is a must for the host function when using Starterware? As i checked the Starterware codes, I found nothing related with the USB1_OCn(GPIO1_26) function, I'm very curious about the USB1_OCn's function during a USB1 host usage, I would appreciate if anyone could give some comments on the details.
2. for the Starterware application, is it all right to use the system power 5V directly as the VBUS?