User's Guide

ThingMagic M6e User Guide 5
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USB Interface
Supports USB 2.0 full speed device port (12 Megabits per second) using the two USB pins (USB_DM and
USB_DP).
Serial Number Added to USB Device Descriptor
Adding a serial number to the USB device descriptor allows the host to assign a COM port number which
follows the device regardless of which physical USB port it is plugged into.
General Purpose Input/Output (GPIO)
The four GPIO connections, provided through the M6e Digital Connector Signal Definition, may be
configured as inputs or outputs using the MercuryAPI. The GPIO pins connect through 100 ohm resistors to
the high current PA0 to PA3 pins of the AT91SAM7X processor. Consult the M6e Specifications for
additional details.
Pins configured as inputs must not have input voltages that exceed voltage range of -0.3 volts to +5.5 volts.
In addition, during reset the input voltages should not exceed 3.3V.
Outputs may source and sink 16 mA. Voltage drop in the series 100 ohm resistor will reduce the delivered
voltage swing for output loads that draw significant current.
Input Mode
• TTL compatible inputs
• Logic low < 0.8 V
• Logic high > 2.0V
• 5V tolerant
Output Mode
• 3.3 Volt CMOS Logic Output with 100 ohms in series
• Greater than 1.9 Volts when sourcing 8 mA
• Greater than 2.9 Volts when sourcing 0.3 mA
• Less than 1.2 Volts when sinking 8 mA
• Less than 0.2 Volts when sinking 0.3 mA
Module power consumption can be adversely affected by incorrect GPIO configuration. Similarly, the power
consumption of external equipment connected to the GPIOs can also be adversely affected. The following
instructions will yield specification-compliant operation.
On power up, the M6e module configures its GPIOs as inputs to avoid contention from user equipment that
may be driving those lines. The input configuration is as a 3.3 volt logic CMOS input and will have a
leakage current not in excess of 400 nA. The input is in an undetermined logic level unless pulled externally
to a logic high or low. Module power consumption for floating inputs is unspecified. With the GPIOs
configured as inputs and individually pulled externally to either high or low logic level, module power
consumption is as listed in the M6e Power Consumption table.
GPIOs may be reconfigured individually after power-up to become outputs. This configuration takes effect
either at API execution or a few tens of milliseconds after power up if the configuration is stored in
nonvolatile memory. The automated configuration into outputs is prevented if the module is held in the boot