User Manual

ThingMagic Nano User Guide 5
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Control Signal Specification
The module communicates to a host processor via a TTL logic level UART serial port, accessed on the
edge “vias.” The TTL logic level UART supports complete functionality.
TTL Level UART Interface
Only three pins are required for serial communication (TX, RX, and GND). Hardware handshaking is not
supported. This is a TTL interface; a level converter is necessary to connect to devices that use a 12V
RS232 interface.
The RX line is a 3.3-volt logic CMOS input and is internally pulled up with a resistance value of between 20
and 60 kOhms (40 kOhms nominal). It must be low before the module is turned off and low before the
module is turned on. This can be ensured if interface drivers are used that are powered by the module
itself, as shown in the interface board example.
The connected host processor’s receiver must have the capability to receive up to 256 bytes of data at a
time without overflowing.
These are the baud rates supported on the interface (bits per second):
• 9600
• 19200
• 38400
• 115200
• 230400
• 460800
• 921600
NOTE: Upon initial power up, the default baud rate of 115200 will be used. If that baud rate is changed
and saved in the application mode, the new saved baud rate will be used the next time the module
is powered up. (Check the firmware release notes to confirm that saving of settings is
supported.)
Output Low-level Voltage 0.3 V typical, 0.7 V maximum
Output High-level Voltage 3.0 V typical, 2.7 V minimum
Output Low-level Current 10 mA maximum
Output High-level Current 7 mA maximum
Voltage and Current Limits
Specification Limits