topic How to soft-reset USB MSD? in 8-bit Microcontrollers

How to soft-reset USB MSD?

leesp — Wed, 26 Mar 2014 08:06:26 GMT

I am implementing a USB MSD Bootloader using MC9s08JM32.

After the bootloading process, the MCU will re-enumerate as a MSD device.

I would like to be able to send a command to soft-reset the MSD device at this point. My application is designed in such way that, if I soft-reset it, it will enter User code and enumerate as a HID device.

Question: How can I soft-reset a MSD device? By sending raw SCSI command? I do not want to implement a composite USB device, so soft-resetting by sending command to HID endpoint is out of the question.

Re: How to soft-reset USB MSD?

david_diaz — Thu, 10 Mar 2016 01:43:28 GMT

Hello Lee,

What do you mean with soft-reset?

In case you are pretending to restart the USB module, you may refer to the following recommendations:

1.Set the USBRESET bit from the USB Control Register 0 (USBCTL0).

2. Set the USBPU bit from the USB Control Register 0 (USBCTL0).

Please find more detailed information at the MC9S08JM32 datasheet , especially at chapter 17.3.1:

I hope this information will be useful for you.

If I misunderstood your question, feel free to let me know. I will be glad to help.

Have a great day.

David Diaz.