B402 Datasheet (001)

Functional description

Overview

The B Series System-on-a-Module (SoM) can act as either a standalone cellular endpoint or LTE enabled gateway for Particle Mesh networks. It is based on the Nordic nRF52840 micro-controller.

The B Series is designed to be integrated into your circuit board design, plugging 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 (Boron LTE)
    • LTE CAT M1 module with global hardware support (MVNO support for US 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
    • IEEE 802.15.4-2006: 250 Kbps
    • 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 mesh system (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 Mesh radio (nRF52840) and a cellular radio (u-blox). We have provided two u.FL connectors to plug in the cellular and Mesh antenna. These are required if you wish to use the cellular and Mesh connectivity.

  • 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 mesh 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

Peripheral Type Qty Input(I) / Output(O)
Digital 24 (max) I/O
Analog (ADC) 8 (max) I
UART 1 I/O
SPI 1 I/O
I2C 1 I/O
USB 1 I/O
PWM 4 (max) O
NFC 1 O

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 E402 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 (128KB, @0xD4000)
  • 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

Pinout

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

Additionally there are reserved pins, whose functions vary depending on the SoM. For example, nRF52 MCU-based modules use some of these pins for additional ADC and GPIO.

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

Pin description

# Pin Common Function nRF52 Description
1 GND GND POWER System ground.
2 VCC VCC POWER System power in, connect to the +LiPo or supply a fixed 3.6-4.2v power.
3 GND GND POWER System ground.
4 VCC VCC POWER System power in, connect to the +LiPo or supply a fixed 3.6-4.2v power.
5 GND GND POWER System ground.
6 VCC VCC POWER System power in, connect to the +LiPo or supply a fixed 3.6-4.2v power.
7 GND GND POWER System ground.
8 VCC VCC POWER System power in, connect to the +LiPo or supply a fixed 3.6-4.2v power.
9 GND GND POWER System ground.
10 3V3 3V3 POWER System power in, supply a fixed 3.0-3.6v power.
11 USB D+ USB D+ IO Data+ pin of the NRF52840 USB port.
12 3V3 3V3 POWER System power in, supply a fixed 3.0-3.6v power.
13 USB D- USB D- IO Data- pin of the NRF52840 USB port.
14 NC RESERVED3 NC Leave unconnected.
15 GND GND POWER System ground.
16 VUSB VUSB POWER System power in, USB detect pin for nRF52840. 5V on this pin enables the USB interface.
17 NFC1 SOM33 NFC input P0.9 NFC antenna connection.
18 NC RESERVED3 NC Leave unconnected.
19 NFC2 SOM43 NFC input P0.10 NFC antenna connection.
20 D1 SCL IO P0.27 I2C SCL, and digital only GPIO.
21 GND GND POWER System ground.
22 D0 SDA IO P0.26 I2C SDA, and digital only GPIO.
23 A0 ADC0 IO P0.3 Analog input ADC02, and digital GPIO.
32 MODE MODE IO P0.11 Connected to the MODE button input, and digital only GPIO.
33 A1 ADC1 IO P0.4 Analog input ADC12, and digital GPIO.
34 RESET RESET I Active-low reset input.
35 A2 ADC2 IO P0.28 Analog input ADC22, and digital GPIO.
36 D9 TX IO P0.6 Primarily used as UART TX, but can also be used as a digital GPIO.
37 A3 ADC3 IO P0.29 Analog input ADC32, and digital GPIO.
38 D10 RX IO P0.08 Primarily used as UART RX, but can also be used as a digital GPIO.
39 AGND AGND POWER System analog ground.
40 D3 RESERVED3 IO P1.1 UART flow control interface CTS, SCL1 (Wire1), SPI1 MOSI, and digital only GPIO.
41 A4 RESERVED3 IO P0.30 Analog input ADC42, and digital GPIO.
42 D2 RESERVED3 IO P1.2 UART flow control interface RTS, SDA1 (Wire1), SPI1 SCK, and digital only GPIO.
43 A5 RESERVED3 IO P0.31 Analog input ADC52, and digital GPIO.
44 u-blox USB D+ SOM0 IO Data+ pin of the R410M USB port.
45 A6 RESERVED3 IO P0.5 Analog input ADC62, and digital GPIO.
46 u-blox USB D- SOM1 IO Data- pin of the R410M USB port.
47 A7 RESERVED3 IO P0.2 Analog input ADC72, and digital GPIO.
48 D8 CS IO P1.3 SPI interface CS, and digital only GPIO.
49 AGND AGND POWER System analog ground.
50 D11 MISO IO P1.14 SPI interface MISO, and digital only GPIO.
51 NC RESERVED3 NC Leave unconnected.
52 D12 MOSI IO P1.13 SPI interface MOSI, and digital only GPIO.
53 NC RESERVED3 NC Leave unconnected.
54 D13 SCK IO P1.15 SPI interface SCK, and digital only GPIO.
55 NC RESERVED3 NC Leave unconnected.
56 GND GND POWER System analog ground.
57 NC RESERVED3 NC Leave unconnected.
58 NC RESERVED3 NC Leave unconnected.
59 NC RESERVED3 NC Leave unconnected.
60 NC RESERVED3 NC Leave unconnected.
61 RGBR RED IO P0.13 Red pin of the RGB LED.
62 D22 GPIO0 IO P0.24 GPIO0, digital only.
63 RGBG GREEN IO P0.14 Green pin of the RGB LED.
64 D23 GPIO1 IO P1.9 GPIO1, digital only.
65 RGBB BLUE IO P0.15 Blue pin of the RGB LED.
66 D4 PWM0 IO P1.8 SPI1 MISO, Digital only GPIO, and PWM0.
67 SIM_VCC1 SOM53 POWER Leave unconnected, 1.8V/3V SIM Supply Output from R410M.
68 D5 PWM1 IO P1.10 Digital only GPIO, and PWM1.
69 SIM_RST1 SOM63 IO Leave unconnected, 1.8V/3V SIM Reset Output from R410M.
70 D6 PWM2 IO P1.11 Digital only GPIO, and PWM2.
71 SIM_CLK1 SOM73 IO Leave unconnected, 1.8V/3V SIM Clock Output from R410M.
72 D7 PWM3 IO P1.12 Digital only GPIO, and PWM3.
73 SIM_DATA1 SOM83 IO Leave unconnected, 1.8V/3V SIM Data I/O of R410m with internal 4.7 k pull-up.
74 u-blox VBUS SOM23 IO USB detect pin for R410M. 5V on this pin enables the u-blox USB interface.
75 NC SOM93 NC Leave unconnected.

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.

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

Parameter Symbol Min Typ Max Unit
Supply voltages
Supply Input Voltage VCC -0.3 +6.0 V
Supply Input Voltage 3V3 -0.3 +3.9 V
VBUS USB supply voltage VUSB -0.3 +5.8 V
I/O pin voltage
VI/O, VDD ≤ 3.6 V IO -0.3 VDD + 0.3 V
VI/O, VDD > 3.6 V IO -0.3 +3.9 V
NFC antenna pin current
INFC1/2 NFC1/NFC2 80 mA
Radio
BT RF input level (52840) 10 dBm
Environmental
Storage temperature -40 +85 °C

[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.

Parameter Symbol Min Typ Max Unit
Supply voltages
Supply Input Voltage VCC +3.6 +3.8 +4.2 V
Supply Input Voltage 3V3 +3.0 +3.3 +3.6 V
VBUS USB supply voltage VUSB +4.35 +5.0 +5.5 V
Environmental
Normal operating temperature1 -20 +25 +65 °C
Extended operating temperature2 -40 +85 °C
Humidity Range Non condensing, relative humidity 95 %

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)


Radio specifications

Boron has two radio modules.

nRF52840

  • Bluetooth® 5, IEEE 802.15.4-2006, 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

Parameter Value
Protocol stack 3GPP Release 13
RAT LTE Cat M1 Half-Duplex
LTE FDD Bands Band 12 (700 MHz)
Band 17 (700 MHz)
Band 28 (700 MHz)
Band 13 (750 MHz)
Band 20 (800 MHz)
Band 26 (850 MHz)
Band 18 (850 MHz)
Band 5 (850 MHz)
Band 19 (850 MHz)
Band 8 (900 MHz)
Band 4 (1700 MHz)
Band 3 (1800 MHz)
Band 2 (1900 MHz)
Band 25 (1900 MHz)
Band 1 (2100 MHz)
LTE TDD bands Band 39 (1900 MHz)
Power class Class 3 (23 dBm)

I/O Characteristics

These specifications are based on the nRF52840 datasheet.

Symbol Parameter Min Typ Max Unit
VIH Input high voltage 0.7 xVDD VDD V
VIL Input low voltage VSS 0.3 xVDD V
VOH,SD Output high voltage, standard drive, 0.5 mA, VDD ≥1.7 VDD - 0.4 VDD V
VOH,HDH Output high voltage, high drive, 5 mA, VDD >= 2.7 V VDD - 0.4 VDD V
VOH,HDL Output high voltage, high drive, 3 mA, VDD >= 1.7 V VDD - 0.4 VDD V
VOL,SD Output low voltage, standard drive, 0.5 mA, VDD ≥1.7 VSS VSS + 0.4 V
VOL,HDH Output low voltage, high drive, 5 mA, VDD >= 2.7 V VSS VSS + 0.4 V
VOL,HDL Output low voltage, high drive,3 mA, VDD >= 1.7 V VSS VSS + 0.4 V
IOL,SD Current at VSS+0.4 V, output set low, standard drive, VDD≥1.7 1 2 4 mA
IOL,HDH Current at VSS+0.4 V, output set low, high drive, VDD >= 2.7V 6 10 15 mA
IOL,HDL Current at VSS+0.4 V, output set low, high drive, VDD >= 1.7V 3 mA
IOH,SD Current at VDD-0.4 V, output set high, standard drive, VDD≥1.7 1 2 4 mA
IOH,HDH Current at VDD-0.4 V, output set high, high drive, VDD >= 2.7V 6 9 14 mA
IOH,HDL Current at VDD-0.4 V, output set high, high drive, VDD >= 1.7V 3 mA
tRF,15pF Rise/fall time, standard drivemode, 10-90%, 15 pF load1 9 ns
tRF,25pF Rise/fall time, standard drive mode, 10-90%, 25 pF load1 13 ns
tRF,50pF Rise/fall time, standard drive mode, 10-90%, 50 pF load1 25 ns
tHRF,15pF Rise/Fall time, high drive mode, 10-90%, 15 pF load1 4 ns
tHRF,25pF Rise/Fall time, high drive mode, 10-90%, 25 pF load1 5 ns
tHRF,50pF Rise/Fall time, high drive mode, 10-90%, 50 pF load1 8 ns
RPU Pull-up resistance 11 13 16
RPD Pull-down resistance 11 13 16
CPAD Pad capacitance 3 pF
CPAD_NFC Pad capacitance on NFC pads 4 pF
INFC_LEAK Leakage current between NFC pads when driven to different states 1 10 μA

1Rise and fall times based on simulations

Mechanical specifications

Dimensions and Weight

Parameters Value Unit
Width 30 mm
Height 42 mm
Thickness 5.5 mm
Weight 6.2 grams

Mechanical drawing

Mechanical Drawing


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.

Connector


Screw Assembly

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

Standoff

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

Bottom

  • As these parts may be difficult to source, for prototyping you can use a M3 screw, 6.5mm long, and a M3 nut. Use a 3mm non-plated hole in the base board. Note that a screw is required, as the M.2 connector does not self-lock.

Design Considerations

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

Keep-Out Area

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 connectors are a very fragile piece of hardware (and is fancy too with all the gold plating). The connector was not designed to be constantly plugged and unplugged. Care must be taken not to put stress on it at any time (yes, swinging the B series by the antenna is a very bad idea, this is not your cat). The antenna pin is also the most static sensitive and you can destroy the radio with improper handling. If you are feeling adventurous, we highly recommend putting a tiny dab of glue (epoxy, rubber cement, liquid tape or hot glue) on the connector to 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

Microcontroller

u-blox cellular modem

u-blox cellular modem

M.2 connector

Connector

SIM and Flash

SIM and Flash

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.

Revision history

Revision Date Author Comments
001 29 Apr 2019 RK Initial Release