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Electrical interface

More detailed information can be found in the relevant datasheet.

Connectors

The TapNLink modules have 3 connectors:

  • P1 extension connector, composed of two rows (P1A and P1B) of contacts.
  • J1 connects the TAP to the target board's debug connector (ARM-SWD standard).
  • J3 connects the TAP to the target board (it is a subset of J1). We recommend you move CLK (SWDCLK) away from DATA (SWDIO). Do not use a ribbon cable with these two signals adjacent. This pdf shows a wiring that has been tested with a 150cm cable.

Cable

The cable between the Tap and the application board must be less than 1 meter (the shorter, the better). You must guard against electromagnetic interference, and you may have to use a shielded cable.

Electrical characteristics

The TAP signals are connected to the main microcontroller via a 22 ohm resistance:

Image

The power source is lowered by a diode (NSR20F30) (typically 250 mV drop) to allow NFC to provide the power supply.

Image

Note: Full Energy harvesting is only available for the NFC-only module (ref TnL-FIT203).

The applicable voltage levels are those of the main MCU (STM32L432K).

Symbol Parameter Min Typ Max Unit
Vtarget(1) Voltage supplied by target 2 3 3.5 V
VIL I/O signals input low level - 0.25xVcc(2) V
VIH I/O signals input high level 0.75xVcc(2) V
VOH Output high level voltage for I/O signals 0.8xVcc - V
VOL Output low level voltage for I/O signals - 0.35xVcc
ICC Current supplied by target 10mA 15mA 18mA mA
  1. Vtarget is the voltage supplied by the application board (the target) at the J1/J3 connector.

  2. VCC is the TAP voltage (typically Vcc = Vtarget – 250mV).

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