Hardware reference guide

7535 Hardware Reference Guide 15
Chapter 2: The Hardware
The Tether Port
USB Client Port
The docking port provides a USB client interface to connect the 7535 to a USB host
computer or hub. The 7535 acts as a USB serial device via the USB client port. On
the 7535, this serial device is COM4. The 7535 also can act as a USB client (a Mass
Storage Device), when its bootloader is running, to allow software updates via USB.
Dock ID
By reading a resistance value, the 7535 can identify the device attached to the
docking port. The Docking Services driver reads the ID, identifying the device,
checks the registry to see which driver to load, then loads the appropriate driver.
2.9.2 The Tether Port
Figure 2.4 The Tether Port
The tether port allows an external non-decoded scanner, a serial scanner, or a USB
client device to be connected to the terminal through a single connector. Generic
serial devices, such as printers, GPS receivers, and other serial devices, are also sup-
ported.
The tether port is COM1.
The 7535’s peripheral controller identifies connected devices by sensing a resistor
within the cable of the connected device. It notifies a driver running on the main
processor that a device has been connected. This driver then looks for an appropriate
driver to load, and instructs the peripheral controller to configure the port appropri-
ately and enable power to the port.
The Tether Port