Introduction

A Wirepas 5G Mesh node has two basic architectures:

• Single-MCU: The application and the Wirepas stack firmware run on the same MCU
• Dual-MCU: The application and the Wirepas stack run on two different MCU’s. The other MCU might be another microcontroller or for example a gateway unit.

Please for more details on architectures and APIs take a look at [1].

Note! Sections preceded by Warning word will highlight important points that must be understood and respected.

Supported SiPs

Wirepas Essential Hardware Requirements

Wirepas 5G Mesh stack firmware is designed to run with Nordic Semiconductor's nRF9161/nRF9151/nRF9131 SiP hardware. The Wirepas 5G Mesh firmware is running in application CPU core and requires Nordic Semiconductor’s NR+ modem firmware which is run in the modem CPU core.

Below chapters are listed the essential HW requirements for a product running Wirepas 5G Mesh firmware. The nRF9161/nRF9151/nRF9131 SiP related HW requirements are provided by Nordic Semiconductor.

External SPI Flash Memory

In order to enable Nordic Semiconductor NR+ modem firmware to be updated as full modem update using Wirepas OTAP, external flash is mandatory to be included in all the nodes in 5G Mesh network (also in sink node).

Interface

• SPI interface
  1. SCK
  2. MOSI
  3. MISO
  4. CS
• recommendation is to use nRF9161/nRF9151/nRF9131 SiP’s Master SPI interface

Size of the external SPI Flash memory

• minimum size is 1 MB (to support modem FW OTAP)
  1. Note! If external flash is intended to be used for other purposes, the use case is dictating the size of external flash thus the end user need to decide the external flash size (> 1 MB)

nRF9161/nRF9151/nRF9131 SiP IOs are using 1.8V - thus the power supply for SPI flash has to be 1.8V (see [4])

Serial Interface (UART)

The serial interface is needed for the sink node for communication with the gateway host processor subsystem.

Interface

• UART interface
  1. RX
  2. TX
• UART pins can be freely selected by HW integrator with the following limitation by Nordic Semiconductor NR+ modem:
  1. Warning: check from Nordic Semiconductor which GPIOs are reserved for the ETM debug trace interface - thus these pins should not be used for UART (or some other purposes)
• The internal pull resistors are not enabled in the default configuration. If necessary, this can be changed by modifying the pin configurations in mcu/nrf/common/hal/usart_dma.c.

nRF9161/nRF9151/nRF9131 SiP IOs are using 1.8V - thus the power supply for UART has to be 1.8V (see [4])

Note (Nordic Thingy:91 X / pca20065 reference hardware)

For the Nordic Thingy:91 X pca20065 retail revision v1.0.0, the onboard nRF53 interface MCU exposes two virtual COM ports (VCOMs) over USB with fixed baud rates:

On this hardware, the Wirepas reference board configuration for pca20065 uses UART_0 / VCOM0 by default, which means that applications intended to use the USB serial interface must be built with a baud rate of 115200 out of the box. It is also possible to use UART_1 / VCOM1 with a baud rate of 1000000 if the corresponding UART pins are selected for the product design.

Older prototype or pre‑production Thingy:91 / pca20065 revisions are not officially supported and may have different UART/USB bridge behaviour.

Programming Interface (SWD)

The initial flashing of nRF9161/nRF9151/nRF9131 SiP is done using the SWD interface. This requires that the nRF9161/nRF9151/nRF9131 SiP SWD interface and nRESET are taken into a flashing and debug connector in the target HW.

Interface

• SWD interface
  1. nRESET
  2. SWDCLK
  3. SWDIO

nRF9161/nRF9151/nRF9131 SiP IOs are using 1.8V - thus the power supply for SPI flash has to be 1.8V (see [4])

The initial programming requires that the modem subsystem and application subsystem is programmed, see flashing guide in [2].

Special Note for Thingy:91x (pca20065 v1.0.0)

The retail Thingy:91x (pca20065) v1.0.0 does not provide a standard J-Link interface via its on-board nRF53 Interface MCU (IMCU).

• The IMCU exposes CMSIS-DAP, not J-Link. Standard J-Link tooling through IMCU will fail.
• Recommended flashing method:
  1. Use an external SEGGER J-Link connected directly to the nRF91 debug pins.
  2. Alternatively, use CMSIS-DAP tooling (e.g., pyOCD) if you choose IMCU path. Wirepas does not guarantee CMSIS-DAP workflows; follow Nordic documentation.
• Warning: Double-check target selection when using the tools and the physical switch on the board selecting whether the nRF91/nRF53 is connected to the debug pins. Ensure you program the nRF91, not the nRF53, to avoid erasing the IMCU firmware.
• Nordic’s preferred upgrade path is via MCUboot, which is not supported by Wirepas firmware.

Nordic Semiconductor Essential Hardware Requirements

nRF9161, nRF9131 and nRF9151 SiPs have different requirements and Nordic Semiconductor customer support and documentation will provide the details. The table below outlines the main differences between the SiPs.

• Warning: for starting the hardware design, it is advised to look at Nordic Semiconductor provided documentation and/or contact Nordic Semiconductor customer support for getting the details on the specific hardware design requirements per SiP - also what calibration is needed for each SiP and the tools for R&D phase and production phase testing.

Harmonized Standard EN 301 406-2 Testing

Harmonized Standard testing is defined in ETSI EN 301 406-2. It consists of radio tests and channel access tests.

Radio tests and needed tools are provided by Nordic Semiconductor. Please contact Nordic Semiconductor for further details on test cases.

Channel access tests and needed tools are provided by Wirepas. See detail in [3].

References

[1] Wirepas Software and APIs Overview 

[2] https://developer.wirepas.com/support/solutions/articles/77000560717

[3] https://developer.wirepas.com/support/solutions/articles/77000566272

[4] nRF9161 power supply & GPIO power supply

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