Hardware Description

GLIDER is built around the Nordic nRF9151 system-in-package, a Cortex-M33 microcontroller with an integrated LTE-M / NB-IoT cellular modem. This page summarises the technical details that matter when integrating, wiring or extending the device.

Block diagram

Microcontroller

SoC	Nordic nRF9151
Core	ARM Cortex-M33 with TrustZone-M
Security extensions	TF-M (Trusted Firmware-M) IPC backend, non-secure execution domain (*_ns target)
Modem	Integrated LTE-M / NB-IoT
Bootloader	MCUboot with dual-image swap (DFU via AT$FW)
Watchdog	120 s hardware watchdog

The firmware target string used by west build is:

gauger_lte/nrf9151/ns

Pinout

The table below lists every GPIO used by GLIDER, taken from gauger_lte_nrf9151_common.dtsi.

Pin	Net	Function	Notes
P0.00	USB_EN	USB bridge power enable	Active high; default off.
P0.01	INT	(Reserved interrupt input)	-
P0.02 / P0.03	I2C3 SDA/SCL	DS2484 1-Wire master	100 kHz I²C.
P0.04 / P0.05 / P0.06	RS_DE / RS_RE / RS_ON	RS-485 driver enable, receive enable, isolator power	RS_ON active high; default off.
P0.07	SLPZ	DS2484 sleep / wake	Active low.
P0.08 / P0.09 / P0.10	LED_Y / LED_R / LED_G	Yellow / red / green status LEDs	Active high.
P0.13 - P0.20	GP0 - GP7	General-purpose analog headers	Routable to AIN7 - AIN0.
P0.21	DI_EN	Digital input power enable	Active high; default off.
P0.22 / P0.23	DI_CH0 / DI_CH1	Isolated digital inputs (CH1 / CH2)	Active high.
P0.24 / P0.25	UART0 RX / TX	USB-C console (via FT234XD)	1 000 000 baud.
P0.26	USB_DETECT	USB-C cable detection	Active low.
P0.27 / P0.28	UART1 RX / TX	JP5 header debug port	115 200 baud.
P0.29 / P0.30	UART2 RX / TX	RS-485 (Modbus RTU) via ISO1212DBQ	19 200 baud, 8E1.
P0.31	BUTTON	User pushbutton	Internal pull-up; active low.

Connectivity

Cellular

• LTE-M and NB-IoT via the on-board nRF9151 modem.
• nano-SIM slot accessible from the outside.
• LTE bands enabled by default: band 8 and band 20 (Europe). Bands can be reconfigured at build time.

USB-C (AT console)

• USB-C connector → FT234XD USB-UART bridge → UART0 of the nRF9151.
• 1 000 000 baud, 8N1.
• The firmware turns the bridge on automatically when it sees USB_DETECT go low (50 ms debounce).
• See AT Console (USB-C).

J-Link (RTT)

• Standard SWD header (SWDIO, SWCLK, GND, VTref).
• RTT (Real-Time Transfer) provides the Zephyr shell and live log stream.
• See RTT Console (J-Link).

1-Wire (W1, W2)

Two electrically equivalent ports on the screw terminal, both driven by the same Maxim DS2484 1-Wire master on the internal I²C3 bus.

• Up to 8 DS18B20 thermometers can be bound to slots simultaneously.
• Up to 12 devices can be enumerated by therm scan in a single sweep.
• See External Temperature Sensors.

Digital inputs (CH1, CH2)

• 2 galvanically isolated channels routed to P0.22 and P0.23.
• Each channel supports disabled, counter and event modes.
• Configurable debounce (active / inactive durations) and cooldown between events.
• See Configuration → Digital Inputs.

RS-485 (Modbus RTU)

• Isolated RS-485 transceiver (ISO1212DBQ) on UART2.
• 19 200 baud, 8E1, RTU framing, 500 ms response timeout.
• Powered only when explicitly enabled (modbus enable) - saves current when idle.
• See Shell Commands → modbus.

Power and timing

Supply rail	Single 3.3 V (typical for nRF9151)
Watchdog timeout	120 s
Default sample period	60 s (app config interval-sample)
Default uplink period	300 s (app config interval-send)
Default downlink watchdog	36 h (app config downlink-wdg-interval; 0 disables)
Peripheral power gating	USB bridge, digital inputs and RS-485 isolator default off - only powered when needed

Indicators and controls

• LEDs (3): red, green, yellow. Driven by GPIO; controllable via the led shell command.
• Button (1): drives app sample / app send actions depending on click pattern:
• 1 click - force send
• 2 clicks - force sample
• 3 clicks - sample then send
• 4 clicks - reboot the device

Firmware

GLIDER firmware is built on Zephyr / nRF Connect SDK with HARDWARIO's HIO SDK on top, which provides the cloud client, configuration framework, button handling, edge detection and the ATCI interpreter.

Build command:

west build -b gauger_lte/nrf9151/ns application

The internal board name is gauger_lte - GLIDER is the commercial product name; both refer to the same hardware.