Rainbow Electronics FARGO MAESTRO 100 (with TCP_IP) - Manual (Page 783)

APPENDIXES
Technical Appendixes
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WM_DEV_OAT_UGD_049 - 001 APPENDIXES August 23, 2007
3.9 USB CDC feature
3.9.1 Software Specification
The Wireless CPU
® implements an Abstract Control Modem as specified in the
Communication Device Class 1.1 specification, therefore a host can use the Wireless
CPU
® either as a Wireless CPU ® device or as a virtual communication port (VCOM).
3.9.2 Managing the USB Feature
3.9.2.1 Enabling the USB Port
To activate the USB feature, in CDC mode, the application must send the
AT+WMFM=0,1,3 command to the Wireless CPU ® . The Wireless CPU ® replies:
• OK if the USB stack successfully started,
• +CME ERROR: 3 if the USB stack failed to start.
From here there is 2 possibilities:
1 – The Wireless CPU ® is wired to the host, the device enumeration is done: if the
enumeration is successfully completed, a VCOM and a Wireless CPU ® device
(viewable in the devices manager) are created at the host side otherwise the
failure is notified to the user (by the host).
2 – The Wireless CPU ® is not wired to the host: the USB stack is waiting for the
USB cable plugging. As soon as the cable is plugged, the enumeration stage
described above starts.
3.9.2.2 Disabling the USB Port
To deactivate the USB feature the application must send the AT+WMFM=0,0,3
command by using either the UART1 or the UART2.
Two cases are supported:
1- The USB stack is running in CDC mode: if the stack is successfully stopped the
Wireless CPU ® replies OK otherwise it replies '+CME ERROR: 3' (note the USB
stack is still running in CDC mode).
2- The USB stack is stopped: the Wireless CPU ® replies unconditionally '+CME
ERROR: 3'.
A Wireless CPU ® reset, whatever its origin, stops the USB stack. If the user has saved
the USB CDC configuration in EEPROM the stack will be restarted while the Wireless
CPU ® is rebooting.
Stopping the USB stack and then disabling the CDC device implies that the VCOM
and Wireless CPU
® are getting unavailable at the host side. The applications using
these resources must be closed since the piece of software drivers they are using
does not longer exist.