Labs Papyr

Overview

Zephyr applications use the nrf52840_papyr board configuration to run on Electronut Labs Papyr hardware. It provides support for the Nordic Semiconductor nRF52840 ARM Cortex-M4F CPU and the following devices:

  • ADC

  • CLOCK

  • FLASH

  • GPIO

  • I2C

  • MPU

  • NVIC

  • PWM

  • RADIO (Bluetooth Low Energy and 802.15.4)

  • RTC

  • SPI

  • UART

  • USB

  • WDT

  • COUNTER

More information about the board is available at https://gitlab.com/electronutlabs-public/papyr.

Hardware

Papyr has two external oscillators. The frequency of the slow clock is 32.768 kHz. The frequency of the main clock is 32 MHz.

Supported Features

The nrf52840_papyr board configuration supports the following hardware features currently:

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

RADIO

on-chip

Bluetooth, ieee802154

RTC

on-chip

system clock

SPI(M/S)

on-chip

spi

UART

on-chip

serial

USB

on-chip

usb

WDT

on-chip

watchdog

Connections and IOs

LED

  • LED1 (green) = P0.13

  • LED2 (blue) = P0.15

  • LED3 (red) = P0.14

Push buttons

  • Reset = SW0 = P0.18 (can be used as GPIO also)

UART

  • TX = P0.8

  • RX = P0.7

I2C

I2C pins connected to onboard sensors (I2C_0):

  • SDA = P0.5

  • SCL = P0.6

SPI

The e-paper display is connected to the chip via SPI on the following pins (SPI_1):

  • SCK = P0.31

  • MOSI = P0.29

  • MISO = P1.1 (not used by the display)

NOTE: P1.1 is pin 33 in absolute enumeration.

Other pins used by the e-paper display are:

  • E-ink enable = P0.11 (cuts off power to the display with MOSFET)

  • CS = P0.30

  • BUSY = P0.3

  • D/C = P0.28

  • RES = P0.2

Programming and Debugging

Applications for the nrf52840_papyr board configuration can be built and flashed in the usual way (see Building an Application and Run an Application for more details); Black Magic Probe debugger presents itself as two USB-serial ports. On Linux, they may come up as /dev/ttyACM0 and /dev/ttyACM1. The first one of these (/dev/ttyACM0 here) is the debugger port. GDB can directly connect to this port without requiring a GDB server by specifying target external /dev/ttyACM0. The second port acts as a serial port, connected to the SoC.

Flashing

By default, papyr is configured to be used with a blackmagicprobe compatible debugger (see _Bumpy).

Applications are flashed and run 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 serial port of Black Magic Probe. For example, under Linux, /dev/ttyACM1.

Then build and flash the application in the usual way.

# From the root of the zephyr repository
west build -b nrf52840_papyr samples/hello_world
west flash

Debugging

Debug and attach configurations are available using Black Magic Probe, and ninja debug, or ninja attach (or with make) are available.

NOTE: You may need to press the reset button once after using ninja flash to start executing the code. (not required with debug or attach)

References