LEA-M8S / LEA-M8T - Hardware integration manual
UBX-15030060 - R06 Hardware description Page 8 of 33
Production information
☞ SPI is not available in the default configuration because its pins are shared with the UART and DDC
interfaces. The SPI interface can be enabled by connecting D_SEL to ground. For speed and clock
frequency, see the NEO / LEA-M8T Data sheet
[2].
1.4.5 TX_READY
The TX_READY function is used to indicate when the receiver has data to transmit. A listener can wait
on the TX_READY signal instead of polling the DDC or SPI interfaces. The UBX-CFG-PRT message lets
you configure the polarity and the number of bytes in the buffer before the TX_READY signal goes
active. The TX_READY function can be mapped to TXD (PIO 06). The TX_READY function is disabled
by default.
☞ The TX_READY functionality can be enabled and configured by AT commands sent to the u-blox
cellular module supporting the feature. For more information, see the GPS Implementation and
Aiding Features in u-blox Wireless Modules [7].
1.5 I/O pins
1.5.1 RESET_N: Reset
Driving RESET_N low activates a hardware reset of the system. Use this pin only to reset the module.
Do not use RESET_N to turn the module on and off, since the reset state increases power
consumption. With LEA-M8S and LEA-M8T module RESET_N is an input only.
☞ The RTC time is also reset (but not BBR).
1.5.2 EXTINT: External interrupt
EXTINT0 and EXTINT1 are external interrupt pins with fixed input voltage thresholds with respect to
VCC (see the LEA-M8S Data sheet
[1] and the NEO / LEA-M8T Data sheet
[2] for more information).
They can be used for wake-up functions in power save mode and for aiding. Leave open if unused.
The EXTINT0 pin can also be configured as a generic PIO (PIO13).
The EXTINT1 pin can also be configured as an active antenna open circuit detection function
(ANT_DET_N). For further information see sections 1.5.5 and 2.4.4.
Power control
The power control feature allows overriding the automatic active/inactive cycle of power save mode.
The state of the receiver can be controlled through the EXTINT0 and EXTINT1 pin. The receiver can
also be forced OFF using EXTINT0 and EXTINT1 when power save mode is not active.
Frequency aiding
The EXTINT0 and EXTINT1 pins can be used to supply time or frequency aiding data to the receiver.
For time aiding, hardware time synchronization can be achieved by connecting an accurate time pulse
to the EXTINT0 pin.
Frequency aiding can be implemented by connecting a periodic rectangular signal with a frequency up
to 500 kHz and arbitrary duty cycle (low/high phase duration must not be shorter than 50 ns) to the
EXTINT0 pin. Provide the applied frequency value to the receiver using UBX messages.
1.5.3 SAFEBOOT_N
The SAFEBOOT_N pin is for future service, updates and reconfiguration.
☞ Do not pull low during reset.
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