We have an issue about USB connection as below.
Could you tell us the suggested configuration range of LDO_USB and LDO_2P5?
(Currently BSP provided their values LDO_USB = 3.2V and LDO_2P5 = 2.5V, but we would like to know your suggested range of them for tuning them.)
If do you know the same issue and solution for it, could you tell us them?
Sometimes i.MX cannot recognize the USB hub.
In this case, i.MX couldn't keep the USB specification Twidch (max 100us) in reset Hand shake protocol.
i.MX over the above time (USB Hub stop the CHIRP K, and i.MX start the CHIRP K.).
We checked the i.MX configuration and its time, and found below result.
1. When we down the LDO_USB voltage, its time is decreased.
2. When the deference of voltage LDO_USB and LDO_2P5 is small, the USB connection will be stable.
MPU : MCIMX6U5EVM10AC
USB Hub : USB2514B-I/M2
OS : Linux 3.14.52 (fsl-yocto-3.14.52_1.1.0)