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reel board

Overview

reel board 1 is a evaluation board based on the Nordic Semiconductor nRF52840 SoC. The board was developed by PHYTEC Messtechnik GmbH in cooperation with Zephyr Project for the Hackathon - “Get Connected”. The board has a built-in debug adapter based on the DAPLink interface firmware and NXP MK20DX128VFM5 SoC.

It is equipped with the Electrophoretic (electronic ink) Display (EPD), environmental (temperature, humidity, light, accelerometer) sensors, and Bluetooth connectivity making it easy to experiment and evaluate the Zephyr OS in these kinds of use cases:

  • battery powered sensor node

  • low-power, low-cost human-machine interface (HMI) for remote control and environmental sensor monitoring

  • temperature and humidity monitor on your table

  • product, name or price tag

  • interactive badge for meetings and conferences

The board provides support for the Nordic Semiconductor nRF52840 ARM® Cortex®-M4F SoC with an integrated 2.4 GHz transceiver supporting Bluetooth® Low Energy and IEEE® 802.15.4.

The schematic can be found on the reel board website 1.

Hardware

On the front of the board are RGB-LED, ADPS9960 and HDC1010 sensors, and Electrophoretic Display. The RGB-LED is controlled by the nRF52840 via GPIO pins. Display is controlled by the nRF52840 via SPI and 3 GPIOs.

On the back side of the board are all other components such as nRF52840, a circuit for the Debug Adapter, On/Off and power source switch, battery holder, buttons and the MMA8652FC (accelerometer) sensor.

ADPS9960 is a Digital Proximity, Ambient Light, RGB and Gesture sensor. HDC1010 is a digital humidity and temperature sensor. MMA8652FC is a 12-bit Digital Accelerometer. All sensors are connected to the I2C bus and one GPIO pin each, which can be used as an interrupt source.

reel board front

reel board front (Credit: PHYTEC)

reel board back

reel board back (Credit: PHYTEC)

Since PCB version 1507.2, the nRF52840 SoC is not soldered directly to the board but integrated as a module on a NOTM.2 adapter. The wiring is identical for versions 1507.1 and 1507.2.

Display

GDEH0213B1 is the display with which the board was introduced in 2018. Unfortunately, this display has been discontinued. Currently the board is delivered with the display GDEH0213B72. It is expected that the display will be replaced over time due the short product lifecycle of this type of displays. The following table lists the displays used on the reel board. The label on the ribbon cable can help to distinguish the displays. According to the display type, the correct designation must be used for building an application.

Display

Ribbon Cable Label

Controller / Driver

Board Designation

Good Display GDEH0213B1

HINK-E0213

SSD1673 / ssd16xx

reel_board

Good Display GDEH0213B72

HINK-E0213A22

IL3897 / ssd16xx

reel_board_v2

Power supply

The board is optimized for low power applications and supports two power source configurations, battery and micro USB connector.

The On/Off switch can choose which power source is used.

reel board uses a TPS610981 boost converter to generate supply voltage for nRF52840 and peripherals (sensors and EPD). The boost converter has two modes:

  • Active mode - supply voltages for nRF52840 and peripherals are on

  • Low Power mode - only supply voltage for nRF52840 is on

The mode is controlled by MODE pin (P1.00).

Note

Actually there is no possibility to reduce energy consumption by the Low Power mode. Both voltages are always on, see: boards/arm/reel_board/board.c

Supported Features

The reel_board board configuration supports the following hardware features:

Interface

Controller

Driver/Component

NVIC

on-chip

nested vectored interrupt controller

RTC

on-chip

system clock

UART

on-chip

serial port

I2C

on-chip

i2c

PWM

on-chip

pwm

SPI

on-chip

spi

GPIO

on-chip

gpio

FLASH

on-chip

flash

RADIO

on-chip

Bluetooth

SENSOR

off-chip

MMA8652FC polling: ADPS9960 polling: HDC1010 polling

Other hardware features are not supported by the Zephyr kernel.

Connections and IOs

Port P0

Name

Function

Usage

P0.00

XL1

32.768 kHz oscillator

P0.01

XL2

32.768 kHz oscillator

P0.02

expansion connector pin 30

None

P0.03

expansion connector pin 31

None

P0.04

expansion connector pin 19

None

P0.05

expansion connector pin 11

None

P0.06

UART0_TX

UART Console over USB

P0.07

Button

user button (S5)

P0.08

UART0_RX

UART Console over USB

P0.09

expansion connector pin 27

None

P0.10

expansion connector pin 29

None

P0.11

RGB LED (red)

GPIO

P0.12

RGB LED (green)

GPIO

P0.13

PWM LED | Buzzer

GPIO

P0.14

EPD Busy output

GPIO

P0.15

EPD Reset input

GPIO

P0.16

EPD DC input

GPIO

P0.17

EPD SPI3_CS

SPI

P0.18

CPU Reset

Reset (S4)

P0.19

EPD SPI3_CLK

SPI

P0.20

EPD SPI3_MOSI

SPI

P0.21

SPI3_MISO

SPI (not connected)

P0.22

HDC1010 DRDYn

GPIO

P0.23

APDS9960 INT

GPIO

P0.24

MMA8652FC INT1

GPIO

P0.25

MMA8652FC INT2

GPIO

P0.26

I2C_0

I2C

P0.27

I2C_0

I2C

P0.28

expansion connector pin 3

None

P0.29

expansion connector pin 52

None

P0.30

expansion connector pin 1

None

P0.31

expansion connector pin 37

None

Port P1

Name

Function

Usage

P1.00

peripheral power on

GPIO

P1.01

expansion connector pin 32

None

P1.02

expansion connector pin 34

None

P1.03

expansion connector pin 17

None

P1.04

expansion connector pin 15

None

P1.05

expansion connector pin 13

None

P1.06

expansion connector pin 33

None

P1.07

expansion connector pin 35

None

P1.08

expansion connector pin 45

None

P1.09

RGB LED (blue)

GPIO

P1.10

expansion connector pin 47

None

P1.11

expansion connector pin 49

None

P1.12

expansion connector pin 51

None

P1.13

expansion connector pin 36

None

P1.14

expansion connector pin 48

None

P1.15

expansion connector pin 50

None

Solder Jumper and Testpoints

There are several labeled solder jumpers on the board. These can be used to connect a logic analyzer to check the behavior of a driver or to measure the voltage of a signal.

reel board Jumper and Testpoints

reel board testpoints (Credit: PHYTEC)

I2C bus and sensors testpoints

Name

Type

Usage

J19

closed solder jumper

testpoint I2C SDA

J20

closed solder jumper

testpoint I2C SCL

J7

closed solder jumper

testpoint INT1 MMA8652FC

J24

closed solder jumper

testpoint INT2 MMA8652FC

J11

closed solder jumper

testpoint INT APDS9960

J12

closed solder jumper

testpoint DRDYn HDC1010

EPD testpoints

Name

Type

Usage

J13

closed solder jumper

testpoint EPD Busy

J14

closed solder jumper

testpoint EPD Reset

J15

closed solder jumper

testpoint EPD DC

J16

closed solder jumper

testpoint EPD SPI_CS

J17

closed solder jumper

testpoint EPD SPI_CLK

J18

closed solder jumper

testpoint EPD SPI_MOSI

Power supply testpoint

Name

Type

Usage

J21

closed solder jumper

testpoint peripheral voltage on/off

TP11

testpoint

testpoint peripheral voltage

TP12

testpoint

testpoint nRF52840 supply voltage VDD_nRF

TP13

testpoint

testpoint boost converter input voltage

Build-in Debug Adapter

The debug adapter is based on the DAPLink interface firmware and NXP MK20DX128VFM5 SoC. The adapter is powered via a micro USB connector and is always on when the board is connected to the USB host. reel board can be flashed and debugged, powered either from battery or USB. If the Adapter is powered via USB, the Adapter circuit heats the board slightly and the temperature sensor can output values up to 1.5 degrees higher.

reel board Debug Adapter

reel board Debug Adapter overview (Credit: PHYTEC)

Debug Adapter Firmware

DAPLink firmware for the adapter can be found at DAPLink reel board Firmware 2. To update the firmware (if necessary), the adapter must be started in bootloader mode. For this, the board should be disconnected from the USB host, the J22 should be closed (use tweezers for this) and the board reconnected to the USB host.

Debug Adapter Jumper

Name

Type

Usage

J3

open solder jumper

close to pass UART TX to external adapter

J4

open solder jumper

close to pass UART RX to external adapter

J22

open solder jumper

close to start adapter in bootloader mode

Adapter LEDs

Name

Type

Usage

D11

green

flashes when adapter is active

D14

red

reserved

D15

yellow

reserved

Expansion Connector

The expansion connector has the same dimensions and similar pinout as the BBC MicroBit edge connector. The expansion components that are designed especially for the reel board are called link boards.

reel board Expansion Connector

reel board Expansion Connector (Credit: PHYTEC)

Programming and Debugging

Applications for the reel_board board configuration can be built and flashed in the usual way (see Building an Application and Run an Application for more details).

Flashing

If you use Linux, create a udev rule (as root) to fix a permission issue when not using root for flashing.

# echo 'ATTR{idProduct}=="0204", ATTR{idVendor}=="0d28", MODE="0666", GROUP="plugdev"' > /etc/udev/rules.d/50-cmsis-dap.rules

Reload the rules and replug the device.

$ sudo udevadm control --reload-rules

Finally, unplug and plug the board again for the rules to take effect.

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.

$ minicom -D <tty_device> -b 115200

Replace <tty_device> with the port where the reel board can be found. For example, under Linux, /dev/ttyACM0.

Then build and flash the application in the usual way.

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

Note

Please use reel_board_v2 to build a application for the board equipped with the GDEH0213B72, see Display.

# From the root of the zephyr repository
west build -b reel_board_v2 samples/hello_world
west flash

Debugging

You can debug an application in the usual way. Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b reel_board samples/hello_world
west debug

Testing the LEDs and buttons

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.