It also may be required to eject the mass storage device, using "Safely Remove Hardware and Eject Media" from the Windows systray. But such a switch is not possible on-the-fly, most probably the board has to be detached from the PC USB port and reconnected, so that Windows has a chance to detect a different device in that port, and attaches it to the proper Windows driver (COM or mass storage). Then it may be possible to check an input pin on startup, and switch the controller into either an COM port or some other (mass storage) port. With two Arduino boards you can make these communicate via SoftwareSerial, so that you can use the Serial Monitor or a terminal program with the COM port of the second board, to display debug information from your mass storage controller, sent to the second board and from there to your PC.Īnother solution may be an Arduino board without an extra 8u2, where both the USB handler and your application code can be implemented in the controller code. I'd never try such an ambitious project, without being familiar with the low-level USB protocols, and without debugging aids for the controller.
Details should be available with the 8u2 firmware, if you ever can find one. More problematic IMO is the communication between the controller and the 8u2, because now your Arduino code must handle the mass storage protocol expected by the 8u2 firmware code. Afterwards you put the programmed chip back into your mass storage board. Then you can program the controller as usual (from the Arduino IDE). you can not program the Arduino (ATmel chip) via COM any more!Ī somewhat simple solution can be a second Arduino board, from which you can remove the controller chip and replace it by the chip for your mass storage board. Once you have updated the 8u2, the Arduino board will behave as such a memory device, no more as a serial device. Drivers for an mass storage port should be part of a Windows distribution as well (external HD, memory sticks.).Įvery USB driver uses its own protocol in the communication with the USB device, so that you'll have to find the appropriate firmware code for the 8u2, that implements the desired protocol. AFAIR Arduino installs its own driver, that turns the USB port into a serial device (COM). Most popular is HID (Human Interface Device), designed for mouse and keyboard input, because such a driver is available in every Windows installation.
USB devices need specific drivers (and protocols) for different device types. A note on USB, please somebody correct me if I'm wrong:
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