B404/B402 Datasheet ⁽⁰¹⁴⁾

Functional description

Overview

The B Series System-on-a-Module (SoM) is a cellular device with support for BLE (Bluetooth LE). It is based on the Nordic nRF52840 micro-controller.

The B Series is designed to be integrated into your circuit board design, plugging into a M.2 NGFF connector on your board, allowing the module to be changed or upgraded easily.

Features

• u-blox SARA-R410-02B LTE modem
  • LTE Cat M1 module
  • Support for United States, Canada, and Mexico only
  • 3GPP Release 13 LTE Cat M1
  • Cat M1 bands: 2, 3, 4, 5, 8, 12, 13, 20, 28
• Nordic Semiconductor nRF52840 SoC
  • ARM Cortex-M4F 32-bit processor @ 64MHz
  • 1MB flash, 256KB RAM
  • Bluetooth 5: 2 Mbps, 1 Mbps, 500 Kbps, 125 Kbps
  • Supports DSP instructions, HW accelerated Floating Point Unit (FPU) calculations
  • ARM TrustZone CryptoCell-310 Cryptographic and security module
  • Up to +8 dBm TX power (down to -20 dBm in 4 dB steps)
  • NFC-A tag
• On-module additional 4MB SPI flash
• 24 mixed signal GPIO (8 x Analog, 4 x PWM), UART, I2C, SPI
• USB 2.0 full speed (12 Mbps)
• JTAG (SWD) pins
• RGB status pins for LED
• Reset and Mode pins for buttons
• On-module MFF2 Particle SIM
• Two on-module U.FL connectors for external antennas
• M.2 interface
• FCC and PTCRB certified
• RoHS compliant (lead-free)

Interfaces

Block diagram

Power

VCC

VCC is used to supply power to the u-blox SARA-R410M cellular module. The recommended input voltage range on this pin is between 3.6V to 4.2V DC. Make sure that the supply can handle currents of at least 2 A.

3V3

3V3 is used to supply power to nRF52840, logic ICs, memory, etc. and 3.3v is recommended. VCC input voltage range is between 3V to 3.6V DC. Make sure that the supply can handle currents of at least 150mA.

VBus

VBus is connected to the USB detect pin of nRF52840 to enables the USB interface. The recommended input voltage range is between 4.35V to 5.5V DC.

Antenna

There are two radios on the B402 module. A BLE radio (nRF52840) and a cellular radio (u-blox). We have provided two u.FL connectors to plug in the cellular and BLE antenna. These are required if you wish to use the cellular and BLE. If you do not need BLE, you do not need to connect the BLE antenna.

Certified Cellular Antenna

• Type: LTE Ultra Wide Band Flex Antenna
• Frequency/band: 698 MHz-2690 MHz
• RoHS Compliant
• Mechanical Specs:
  • Dimensions: 97 x 21 x 0.2 mm
  • Mounting: 3M adhesive backed for application on non-metallic surfaces
  • Connector type: FPC + IPEX connector
  • Cable length: 210 mm
  • Gain: 4.71 dBi

General Antenna Guidance

• The antenna placement needs to follow some basic rules, as any antenna is sensitive to its environment. Mount the antenna at least 10mm from metal components or surfaces, ideally 20mm for best radiation efficiency, and try to maintain a minimum of three directions free from obstructions to be able to operate effectively.
• Needs tuning with actual product enclosure and all components.
• For the BLE antenna, it is recommended to use a 2.4 GHz single-frequency antenna and not a 2.4 GHz + 5 GHz antenna, so as to avoid large gain at the frequency twice of 2.4 GHz which can cause the second harmonic radiation of 2.4 GHz to exceed standards.

Peripherals and GPIO

There are some optional B402 module specific I/O:

• u-blox USB and VBUS (for u-blox firmware upgrades)

Note: All GPIOs are only rated at 3.3VDC max.

JTAG and SWD

The B402 module has 4 pads at the bottom exposing the SWD interface of the nRF52840. This interface can be used to debug your code or reprogram your B402 bootloader, device OS, or the user firmware. We use 4 pogo-pins connecting to these pads during production for firmware flashing.

Memory map

nRF52840 Flash Layout Overview

• Bootloader (48KB, @0xF4000)
• User Application
  • 256KB @ 0xB4000 (Device OS 3.1 and later)
  • 128KB @ 0xD4000 (Device OS 3.0 and earlier)
• System (656KB, @0x30000)
• SoftDevice (192KB)

External SPI Flash Layout Overview (DFU offset: 0x80000000)

• OTA (1500KB, @0x00289000)
• Reserved (420KB, @0x00220000)
• FAC (128KB, @0x00200000)
• LittleFS (2M, @0x00000000)

Pins and button definitions

Pinout diagram

Pins SOM0 to SOM9 will vary across various SoM modules. For example, cellular-specific pins exists in this range.

Additionally there are RESERVED³ pins, whose functions vary depending on the SoM. For example, nRF52 MCU-based modules use some of these pins for additional ADC and GPIO. They are able to be used as described on the B402, but their function may be be different on future modules.

For maximum cross-module flexibility, you should try to use only the common pins when possible.

Pin description

¹These pins are connected to the internal MFF2 SIM and should be left open.

²A0-A7 are 12-bit Analog-to-Digital (A/D) inputs (0-4095).

³SoM-specific and Reserved pins will vary depending on module. They are able to be used on the B402, but their function may be be different on future modules.

By default, the Tinker application firmware enables the use of the bq24195 PMIC and MAX17043 fuel gauge. This in turn uses I2C (D0 and D1) and pin A6 (PM_INT). If you are not using the PMIC and fuel gauge and with to use these pins for other purposes, be sure to disable system power configuration. This setting is persistent, so you may want to disable it with your manufacturing firmware only.

System.setPowerConfiguration(SystemPowerConfiguration());

If you are using Ethernet with the B Series SoM, the following pins are used by Ethernet:

LED status

System RGB LED

Unlike the Boron, the B402 module does not have an on-module RGB system status LED. We have provided its individual control pins for you to connect an LED of your liking. This will allow greater flexibility in the end design of your products.

A detailed explanation of different color codes of the RGB system LED can be found here.

Technical specifications

Absolute maximum ratings ^[1]

Supply voltages

^[1] Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

Recommended operating conditions

Notes:

¹ Normal operating temperature range (fully functional and meet 3GPP specifications).

² Extended operating temperature range (RF performance may be affected outside normal operating range, though module is fully functional)

Power consumption

¹The min, and particularly peak, values may consist of very short transients. The typical (typ) values are the best indicator of overall power consumption over time. The peak values indicate the absolute minimum capacity of the power supply necessary, not overall consumption.

Radio specifications

Boron has two radio modules.

nRF52840

• Bluetooth® 5, 2.4 GHz
  • 95 dBm sensitivity in 1 Mbps Bluetooth® low energy mode
  • 103 dBm sensitivity in 125 kbps Bluetooth® low energy mode (long range)
  • 20 to +8 dBm TX power, configurable in 4 dB steps

u-blox SARA-R410M-02-B

I/O Characteristics

These specifications are based on the nRF52840 datasheet.

• Rise and fall times based on simulations

• GPIO default to standard drive (2mA) but can be reconfigured to high drive (9mA) in Device OS 2.0.0 and later using the pinSetDriveStrength() function.

Mechanical specifications

Dimensions and Weight

Mechanical drawing

Dimensions are in millimeters.

Mating connector and land pattern

The mating connector is a an M.2 (NGFF) type 4. Note that there are several different key configurations for the M.2, and type 4 is different than is commonly used on SSDs.

One compatible connector is the TE 2199230-4. It is widely available including at suppliers such as DigiKey.

Screw Assembly

We recommend this screw assembly to securely affix the B series SoM to your circuit board. From top to bottom:

• M3 screw, 3mm long
• M3 washer
• M3 standoff, 2.45mm

• Mounting hole, 2.6 mm metal hole, 3.1mm metal ring diameter (picture is of the bottom side of the circuit board)

• An alternative design uses a JAE SM3ZS067U410-NUT1-R1200 standoff. It's reflow soldered to your base board and has a threaded hole for a M2*3 screw to hold down the SoM. This may be easier to obtain.

• Note that a hold-down screw is required because the M.2 connector does not have integrated locks and the SoM will pop up if not attached to the base board.

Design Considerations

We strongly recommend against placing components under the SOM board because there is not enough height.

Product Handling

ESD Precautions

The B series contains highly sensitive electronic circuitry and is an Electrostatic Sensitive Device (ESD). Handling an B series without proper ESD protection may destroy or damage it permanently. Proper ESD handling and packaging procedures must be applied throughout the processing, handling and operation of any application that incorporates the B series module. ESD precautions should be implemented on the application board where the B series is mounted. Failure to observe these precautions can result in severe damage to the B series!

Connectors

The U.FL antenna connector is not designed to be constantly plugged and unplugged. The antenna pin is static sensitive and you can destroy the radio with improper handling. A tiny dab of glue (epoxy, rubber cement, liquid tape or hot glue) on the connector can be used securely hold the plug in place.

The M.2 edge connector is static sensitive and should be handled carefully. The M.2 connector is not designed for repeated removal and insertion of the module.

Schematics

Microcontroller

u-blox cellular modem

M.2 connector

Note: The labels for CTS and RTS are reversed in this schematic.

SIM and Flash

Buffers

Default settings

The B series comes pre-programmed with a bootloader and a user application called Tinker. This application works with an iOS and Android app also named Tinker that allows you to very easily toggle digital pins, take analog and digital readings and drive variable PWM outputs.

The bootloader allows you to easily update the user application via several different methods, USB, OTA, Serial Y-Modem, and also internally via the Factory Reset procedure. All of these methods have multiple tools associated with them as well.

Country compatibility

Ordering information

Revision history