NINA-W1 series - User Manual
⚠ When taking VCC supplies from an SMPS make sure that the AC ripple voltage is kept as low as
possible at the switching frequency. Design layouts should focus on minimizing the impact of
any high-frequency ringing.
Use an LDO linear regulator for primary VCC supplies that have a relatively low voltage. As LDO
linear regulators dissipate a considerable amount of energy, LDOs are not recommended for the
step down of high voltages.
DC/DC efficiency should be regarded as a trade-off between the active and idle duty cycles of an
application. Although some DC/DC devices achieve high efficiency at light loads, these efficiencies
typically degrade as soon as the idle current drops below a few milliamps. This can have a negative
impact on the life of the battery.
If decoupling capacitors are needed on the supply rails, it is best practice to position these as close
as possible to the NINA-W1 series module. The power routing of some host system designs makes
decoupling capacitance unnecessary.
For electrical specifications, see the NINA-W1 series Data Sheets.
1.5 System function interfaces
1.5.1 Boot strapping pins
For normal operation, several boot configuration pins must be in their default state during the
module boot. Left unconnected in the application design, the default state of these pins is
automatically chosen with internal pull-up or pull-down resistors in the module. See data sheet for
more information.
Care must be taken if an RMII interface is to be included in the application design. Pin 25 and pin 27
connect to the RMII. It is important that both of these pins are in the correct state during the
module boot and before the RMII interface turns on. For connection information, see section 1.6.2.1.
☞ On NINA-W13/W15 modules, pin 25 and pin 27 must be in default state during the boot.
☞ On NINA-W10 modules, pin 27 is used to enter the ESP bootloader. Consequently, this pin must
be exposed on a pin header (or similar) to flash the module.
Pin 32 is used to control the Universal Asynchronous Serial Interface (UART) debug printout. With
this pin left unconnected, NINA-W1 prints some short debug information when it boots before the
module software starts up. For u-connectXpress software, this means before +STARTUP. To disable
the printout, this pin must be pulled low during start-up.
1.6 Data interfaces
1.6.1 Universal asynchronous serial interface (UART)
For data communication and firmware upgrade, NINA-W1 series modules support an interface
comprised of three UARTs. Each UART supports the following signals:
Data lines (RXD as input, TXD as output)
Hardware flow control lines (CTS as input, RTS as output)
DSR and DTS set and indicate the system modes
You can use the UARTs in 4-wire mode with hardware flow control, or in 2-wire mode with TXD and
RXD only. In 2-wire mode, CTS must be connected to the GND on the NINA-W1 module.
For further information, see chapter 2.
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