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Sentrius BT610 Sensor

Overview

The Sentrius™ BT610 Sensor is a battery powered, Bluetooth v5 Long Range integrated sensor platform that uses a Nordic Semiconductor nRF52840 ARM Cortex-M4F CPU.

The sensor has the following features:

  • ADC

  • CLOCK

  • FLASH

  • GPIO

  • I2C

  • MPU

  • NVIC

  • PWM

  • QSPI

  • RADIO (Bluetooth Low Energy and 802.15.4)

  • RTC

  • Segger RTT (RTT Console)

  • SPI

  • UART

  • WDT

Sentrius BT610 Sensor, rear view

Sentrius BT610 Sensor, rear view

More information about the board can be found at the Sentrius BT610 website [1].

Hardware

Supported Features

The BT610 Sensor supports the following hardware features:

Interface

Controller

Driver/Component

ADC

on-chip

adc

CLOCK

on-chip

clock_control

FLASH

on-chip

flash

GPIO

on-chip

gpio

I2C(M)

on-chip

i2c

MPU

on-chip

arch/arm

NVIC

on-chip

arch/arm

PWM

on-chip

pwm

QSPI

on-chip

qspi

RADIO

on-chip

Bluetooth, ieee802154

RTC

on-chip

system clock

RTT

Segger

console

SPI(M)

on-chip

spi

UART

on-chip

serial

WDT

on-chip

watchdog
Sentrius BT610 Sensor, board layout

Sentrius BT610 Sensor, board layout

Connections and IOs

LED

Two LEDs are visible through the BT610 housing lid. Note that the LEDs can be driven either directly, or via PWM. PWM should be used when current consumption is required to be minimised.

  • LED_1 (red) = LED0 = P1.07 (Red LED 1)

  • LED_2 (green) = LED1 = P1.03 (Green LED 2)

  • LED_PWM_1 (red) = LED0PWM = P1.07 (Red PWM LED 1)

  • LED_PWM_2 (green) = LED1PWM = P1.03 (Green PWM LED 2)

Push button

The BT610 incorporates three mechanical push buttons. Note these are only accessible with the housing cover removed.

Two of the buttons are available for use via the board DTS file, as follows.

  • BUTTON_1 = SW0 = P0.24 (Boot button SW1)

  • BUTTON_2 = SW1 = P1.01 (Tamper switch SW2)

A third mechanical push button is provided to allow reset of the on-board microcontroller.

Magnetoresistive sensor

The BT610 incorporates a Honeywell SM351LT magnetoresistive sensor. Refer to the Honeywell SM351LT datasheet [2] for further details.

  • MAG_1 = SW2 = P1.15 (SM3531LT_0)

External flash memory

A 64Mbit external flash memory part is available for storage of application images and data. Refer to the Macronix MX25R6435FZNIL0 datasheet [6] for further details.

The flash memory is connected to the on-board QSPI device controller.

  • MX25R64 = QSPI

Voltage reference

A precision 2.5V voltage reference is provided on the V_REF input for use during AD measurements.

This can deliver up to 50mA peak and 20mA continuous current.

Sensor connectivity

The BT610 incorporates three terminal blocks J5, J6 & J7 that allow connectivity to its sensor inputs, as follows.

Terminal Block J5

Pin No.

Name

Description

Direction

1

EXT_SPI_CS_2

External SPI CS 2

OUT

2

GND

GND

(N/A)

3

AIN4

Analog Input 4

IN

4

AIN3

Analog Input 3

IN

5

GND

GND

(N/A)

6

AIN2

Analog Input 2

IN

7

AIN1

Analog Input 1

IN

8

GND

GND

(N/A)

9

DIN2

Digital Input 2

IN

10

DO2

Digital Output 2

OUT

Terminal Block J6

Pin No.

Name

Description

Direction

1

DO1

Digital Output 1

OUT

2

DIN1

Digital Input 1

IN

3

GND

GND

(N/A)

4

THERM4

Thermistor Input 4

IN

5

THERM3

Thermistor Input 3

IN

6

GND

GND

(N/A)

7

THERM2

Thermistor Input 2

IN

8

THERM1

Thermistor Input 1

IN

9

GND

GND

(N/A)

10

B+ OUT

Ext. sensor power supply

(N/A)

Terminal Block J7

Pin No.

Name

Description

Direction

1

UART_1_RTS

UART 1 RTS

IN

2

UART_1_CTS

UART 1 CTS

OUT

3

UART_1_RXD

UART 1 RXD

IN

4

UART_1_TXD

UART 1 TXD

OUT

5

EXT_I2C_SCL

External I2C SCL

OUT

6

EXT_I2C_SDA

External I2C SDA

IN/OUT

7

EXT_SPI_CLK/TRACEDATA3

Ext. SPI CLK/TRACE DATA 3

OUT

8

EXT_SPI_MISO

External SPI MISO

IN

9

EXT_SPI_MOSI

External SPI MOSI

OUT

10

EXT_SPI_CS_1

External SPI CS 1

OUT

Analog inputs

The four external Analog Inputs are multiplexed to a single host microcontroller AD input, AIN_1, via a TI TMUX1204 multiplexer.

Refer to the TI TMUX1204 datasheet [4] for further details.

Signals up to 12V, to a maximum of 50mA, can be applied to the external Analog Inputs.

External Analog Input connections are made to the multiplexer as follows.

Input

MUX Input

AIN1

S1

AIN2

S2

AIN3

S3

AIN4

S4

A TI TCA9538 port expander is used to determine the mode of each Analog Input, for either voltage or current measurement, and also to control the mutliplexer. A high level applied to the appropriate expander port pin enables the associated analog input as a current input; when a low logic level is applied, voltage measurement mode is selected.

Refer to the TI TCA9538 datasheet [5] for further details.

The expander port connections are as follows.

Pin

Function

P0

AIN1 mode

P1

AIN2 mode

P2

AIN3 mode

P3

AIN4 mode

P4

MUX A0

P5

MUX A1

P6

(N/C)

P7

(N/C)

The following illustrates some possible configuration values for the port expander. Note that it is possible for combinations of voltage and current measurement to be applied such that some external Analog Inputs measure current and others voltage. This is not shown below.

Expander value

Selected Analog Input & mode

b’00000000’

AIN1, voltage measurement

b’00000001’

AIN1, current measurement

b’00010000’

AIN2, voltage measurement

b’00010010’

AIN2, current measurement

b’00100000’

AIN3, voltage measurement

b’00100100’

AIN3, current measurement

b’00110000’

AIN4, voltage measurement

b’00111000’

AIN4, current measurement

Circuitry associated with the analog input measurements can be disabled when not in use.

A GPIO is used to control this behaviour, as shown below.

ANALOG_ENABLE

Behaviour

0

Disabled

1

Enabled

Thermistor inputs

The four external thermistor inputs are connected to a single AD input, AIN_2, via a TI TMUX1204 multiplexer.

Refer to the TI TMUX1204 datasheet [4] for further details.

External analog input connections are made to the multiplexer as follows.

Input

MUX Input

THERM1

S1

THERM2

S2

THERM3

S3

THERM4

S4

The same port expander used to select external analog inputs is also used to select external thermistor inputs.

The table below defines possible values that can be written.

Expander value

Selected Analog Input

b’00000000’

THERM1

b’00010000’

THERM2

b’00100000’

THERM3

b’00110000’

THERM4

A GPIO line is used to enable electronics associated with thermistor measurement. This is controlled as shown below.

THERM_ENABLE

Behaviour

0

Enabled

1

Disabled

Note the thermistor circuit must be calibrated before use. A suggested method for achieving this is described in the BT610 Zephyr Application Thermistor Calibration [7] application note.

Digital inputs

Two external digital inputs are available for connection to external signals. For the digital level being applied to be detected, an appropriate output pin must first be set. This approach is taken to ensure supporting circuitry can be powered down when the input state is not being determined. When in use, the external digital input level can be read from the appropriate input pin.

The output and input pins required are as follows.

Enable Pin

Input Read Pin

DIN_1_ENABLE

DIN_1

DIN_2_ENABLE

DIN_2

Digital outputs

Two external digital outputs are available to provide signals to or to directly drive external equipment.

To provide a high level on the external digital output, a high logic level is applied to the appropriate host microcontroller output.

The output pins required are as follows.

Output Pin

External Sensor Terminal

DO_1_MCU

DO1

DO_2_MCU

DO2

External power supply

Power can be supplied to external sensors via the B+ OUT terminal. This is enabled by setting the BATTERY_OUTPUT_ENABLE GPIO line. In addition, the external supply can be boosted to 5V by setting the HIGH_SUPPLY_ENABLE GPIO line. When 5V is not selected, the external power supply follows the battery voltage.

Up to 50mA peak and 20mA continuous current can be delivered by the External Power Supply.

External sensor I2C port

External I2C sensors can be connected on the external I2C port. Note that external I2C sensors should be powered from the B+ terminal to ensure applied voltage levels match those expected internally by the board.

Required pins are as follows.

Output Pin

External Sensor Terminal

SCL_PIN

EXT_I2C_SCL

SDA_PIN

EXT_I2C_SDA

External sensor SPI port

Up to 2 external SPI sensors can be connected on the external SPI port. Note that external SPI sensors should be powered from the B+ terminal to ensure applied voltage levels match those expected internally by the board.

Required pins are as follows.

Output Pin

External Sensor Terminal

SCK_PIN

EXT_I2C_SCL

MOSI_PIN

EXT_I2C_SDA

MISO_PIN

EXT_SPI_MISO

SDA_PIN

EXT_I2C_SDA

CS_GPIOS

EXT_I2C_SDA

CS_GPIOS

EXT_I2C_SDA

Programming and Debugging

Applications for the bt610 board configuration can be built and flashed in the usual way (see Building an Application and Run an Application for more details); however, the standard debugging targets are not currently available.

The BT610 features a 10 way header, J3, for connection of a programmer/debugger, with pinout as follows.

Pin No.

Name

Description

1

3.3V

Power Supply, 3.3V

2

SWDIO

Data Input/Output

3

GND

GND

4

SWDCLK

Clock Pin

5

GND

GND

6

SWO

Trace Output Pin

7

(N/C)

Not Connected

8

(N/C)

Not Connected

9

GND

GND

10

nRESET

Reset Pin

Access to the sensor debug UART is facilitated by a 6 pin header, J1, with pinout as follows.

Pin No.

Name

Description

Direction

1

GND

GND

N/A

2

UART_0_RTS

UART 0 RTS Pin

IN

3

3.3V

Power Supply, 3.3V

N/A

4

UART_0_RX

UART 0 RX Pin

IN

5

UART_0_TX

UART 0 TX Pin

OUT

6

UART_0_CTS

UART 0 CTS Pin

OUT

Note that pin 3 requires a solder bridge to be closed to enable powering of the BT610 board via the UART connector.

Flashing

Follow the instructions in the Nordic nRF5x Segger J-Link page to install and configure all the necessary software. Further information can be found in Flashing. Then build and flash applications as usual (see Building an Application and Run an Application for more details).

Here is an example for the Hello World application.

First, run your favorite terminal program to listen for output.

NOTE: On the BT610, the UART lines are at TTL levels and must be passed through an appropriate line driver circuit for translation to RS232 levels. Refer to the MAX3232 datasheet [3] for a suitable driver IC.

$ minicom -D <tty_device> -b 115200

Replace <tty_device> with the port where the BT610 can be found. For example, under Linux, /dev/ttyUSB0.

Then build and flash the application in the usual way.

# From the root of the zephyr repository
west build -b bt610 samples/hello_world
west flash

Note that an external debugger is required to perform application flashing.

Debugging

The bt610 board does not have an on-board J-Link debug IC as some nRF5x development boards, however, instructions from the Nordic nRF5x Segger J-Link page also apply to this board, with the additional step of connecting an external debugger.

Testing Bluetooth on the BT610

Many of the Bluetooth examples will work on the BT610. Try them out:

Testing the LEDs and buttons on the BT610

There are 2 samples that allow you to test that the buttons (switches) and LEDs on the board are working properly with Zephyr:

You can build and flash the examples to make sure Zephyr is running correctly on your board. The button, LED and sensor device definitions can be found in boards/ezurio/bt610/bt610.dts.

References