Modes
USB direct mode
Digi XBee3 Cellular LTE-M/NB-IoT Global Smart Modem User Guide
125
USB direct mode
Note
In order to use USB direct mode in Digi XBee development kits, you must use the XBIB-C-TH
development board.
Note
You should use this mode if you want to connect using PPP through the cellular modem while
using a host operating system, such as embedded Linux.
This mode allows you to access the XBee Smart Modem's USB interface directly through XBee pins 7
and 8. VBUS functionality is optionally provided on XBee pin 6 if you wish to enable and disable USB
mode based on an external source. While in USB mode the cellular modem is not able to communicate
serially with the XBee MCU. All communication with the cellular modem must be performed by the
user via the USB port.
Configure the data pins
Set
to
7
to configure pins 7 and 8 for USB direct mode.
If USB Direct is not enabled (
P1
is not set to
7
), then
bit 2 and
P0
being set to
6
have no effect on the USB VBUS state.
Enable USB direct mode
You can enable USB direct mode in two ways:
1. Enable via software: Set
bit 2. Ensure that
is not set to
6
as that would override the
DO
setting.
2. Enable based on the state of VBUS (pin 6): Set
P0
to
6
. Apply a logic high signal to DIO10/PWM0
(pin 6) to enable USB or a logic low signal to disable USB.
Note
Although pin 6 is 5 V tolerant on this device, it operates with the same 3.3 V logic as the other
XBee device pins. For compatibility with other XBee devices we recommend driving the line with no
more than 3.3 V. Moreover, driving the pin at 5 V will cause input leakage current to increase to 3.3 µA
typical.
You must reset the device to enable or disable USB direct mode.
While in USB direct mode,
returns 0x2B.
Bypass operating mode (DEPRECATED)
WARNING!
Bypass mode is now deprecated and is not recommended for new designs.
XBee3 Cellular products support direct USB to access the cellular modem directly. See
for details on how to configure your XBee to use direct USB.
CAUTION!
Bypass operating mode is an alternative to Transparent and API modes for
advanced users with special configuration needs. Changes made in this mode might change
or disable the device and we do not recommended it for most users.