ThingMagic M6e - Manual (Page 28)

Hardware Interfaces
A D I V I S I O N O F T R I M B L E
28 Hardware Overview
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 configuration to outputs is
defeated if the module is held in the boot loader by
Reset Line being held low. Lines
configured as outputs consume no excess power if the output is left open. Specified
module power consumption is achieved for one or more GPIO lines set as output and left
open. Users who are not able to provide external pull ups or pull downs on any given
input, and who do not need that GPIO line, may configure it as an output and leave it
open to achieve specified module power consumption.
Configuring GPIO Settings
The GPIO lines are configured as inputs or outputs through the MercuryAPI by setting the
reader configuration parameters /reader/gpio/inputList and /reader/gpio/outputList. Once
configured as inputs or outputs the state of the lines can be Get or Set using the gpiGet()
and gpoSet() methods, respectively. See the language specific reference guide for more
details.
Reset Line
Upon power up the RESET (pin 15) line is configured as an input. The input value will
determine whether the
Boot Loader (pulled LOW) will wait for user commands or
immediately load the Application Firmware (left open) image and enter application mode.
After that action is completed, this line is configured as an output line. While the unit
continues to be in bootloader the line is driven high.
Once in application mode, the RESET line is driven low. if the module returns to the
bootloader mode, either due to an assert or “boot bootloader”, the RESET line will again
be driven high.
To minimize power consumption in the application, the RESET line should be either left
open or pulled weakly low (1.5k Ohm to ground).
See Note about baud rate applicable when using TTL Level UART Interface .