topic iMX233 USB connection mode in i.MX Processors

iMX233 USB connection mode

paolomartinetti — Sun, 21 Feb 2016 01:08:38 GMT

Hi everybody.

i have some problem with my device, 233-equipped, when i plug USB cable first on computer and after in device.

The device-plug probably connects D+/ D- pins before power and ground ones.

Could be this wrong? After this 'bad' connection, my device stops working and seems powered off.

Is there any way to avoid this acting on kernel code?

Thanks in advance

igorpadykov — Mon, 22 Feb 2016 01:50:44 GMT

Hi Paolo

it is not allowed to apply voltages to unpowered processor.

This can not be configured in software.

Best regards

igor

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paolomartinetti — Tue, 23 Feb 2016 13:14:49 GMT

My device is powered with a Li-Ion battery. I attach USB connecting data pins before Power and Ground pins.

igorpadykov — Tue, 23 Feb 2016 13:35:52 GMT

it does not matter, if processor is not turned on

(unpowered)

Power-up can be started with one of several events:

PSWITCH pin >= minimum MID level PSWITCH for 100 ms

VDD5V power pin > 4.25 V for 100 ms