Ublox EVK-NORA-B1, Руководство пользователя

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EVK-NORA-B1 - User guide
UBX-20030319 - R06 Hardware description Page 9 of 31
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2.2 Reset
The EVK-NORA-B1 provides a configurable hardware reset to the NORA-B1 module. The Reset button
can be configured to connect to an input on the interface IC or to directly connect to
nRESET signal in
the module.
The reset button is connected to the debug interface chip by default. Pressing reset while the
interface IC is powered causes a momentary reset signal on the
nMOD_RESET output of the interface
IC, which converted to the VSYS I/O voltage for the module. If the reset button is held down during the
EVK power on, it causes the interface IC to enter its bootloader mode, which allows programming of
the SEGGER J-Link interface.
Solder jumpers JRST1 and JRST2 allow the reset button to bypass the interface circuit and connect
directly to the nRESET signal on the module.
Figure 3: EVK schematic – reset
Signal name Description
IMCU_BOOT Input to interface chip. During normal operation, drive low to reset the NORA-B1. Drive low during
power-up to enter bootloader mode on the interface chip.
nRESET NORA-B1 reset signal at the NORA-B1 I/O voltage.
nMOD_RESET NORA-B1 reset signal at the interface chip I/O voltage.
nSHLD_RESET I/O header shield reset signal (J27, pin 3)
Table 3: EVK reset signals
2.3 Buttons
The evaluation board has four user buttons that are active low and connect to ground when pressed.
Table 4 associates the button number and corresponding components.
Button Switch GPIO Jumper Protection diode
1 SW4 P0.23 J24 D7
2 SW5 P0.24 J21 D8
3 SW7 P0.08 J22 D11
4 SW8 P0.09 J23 D12
Table 4: User button components
The internal pull-up resistor of each NORA-B1 GPIO pin must be enabled for proper operation.
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Example programs in the SDK enable the pull-up resistors by default.
The buttons and ESD protection can be completely removed from the circuit by breaking the
associated jumper.