What is the "Reserved USB_FS_M deselect" pin?

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What is the "Reserved USB_FS_M deselect" pin?

Post by admin » Wed Jul 15, 2015 2:06 pm

All Decaf boards (LCD and IOC) are USB2, and the boards have to appear as a USB Device, rather than as a USB Host. This is done by asserting one of the USB signals (USB_FS_M) while the board is operational. This is done with a transistor circuit that is controlled by one of the GPIO port pins. This control circuit is built on to all the LCD host boards except for the Decaf-0. On the Decaf-0 and IOC boards, the circuit is on the IO daughter pcb, and connects to the USB-FS_M jumper.

The USB-FS_M circuit used for two operations:
[*] The Device Firmware Upgrade utility. After the upgrade is done, the utility has a "Exit DFU mode" button (in effect a reboot) and the control signal is cycled to disconnect and reconnect the Defac board.
[*] The HID REBOOT command when issued from an app does the same.
Stewart (Admin) @ pixcl

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