Board: Airfy Beacon

Overview

The Airfy Beacon is utilizing a Nordics NRF51822QFAA SoC. The SoC features 16Kb of RAM, 256Kb of flash ROM and comes on top of the usual micro-controller peripherals with a 2.4GHz radio that supports both Nordics proprietary ShockBurst as well as Bluetooth Low Energy (BLE).

The board was available via Indiegogo.

Hardware

MCU	NRF51822QFAA
Family	ARM Cortex-M0
Vendor	Nordic Semiconductor
RAM	16Kb
Flash	256Kb
Frequency	16MHz
FPU	no
Timers	3 (2x 16-bit, 1x 32-bit [TIMER0])
ADCs	1x 10-bit (8 channels)
UARTs	1
SPIs	2
I2Cs	2
Vcc	1.8V - 3.6V
Reference Manual	Reference Manual

Unlocking the flash memory

If you're holding a new device in your hands, there is a high change that your device's flash memory is locked and RIOT's make flash command will fail, saying something like erasing the flash was not possible.

A solution for this is to reset the chips code memory and user information registers. Just follow these steps:

1. Follow the steps described above for manually flashing the device:

   1. start openocd using the correct config file openocd -f boards/airfy-beacon/dist/openocd.cfg
   2. connect to openocd using telnet telnet localhost 4444

2. type halt to stop the device

3. type nrf51 mass_erase to reset the code memory

4. all done, make flash should now work as expected.

Flashing and Debugging

The Airfy Beacon comes without any on-board programming and flashing capabilities. It supports however to be programmed using off-the-shelf programmers such as Segger's JLink or STM's STLink.

A very simple and affordable way to program and debug this module is to use the integrated ST-Link/V2 programmer of any STM32Fx-discovery board. The needed steps are described in the following sections. If you want to use a standalone ST-Link adapter, you just simply have to alter the wiring to fit for your programmer, the software part is identical.

Hardware

First of all make sure the your ST-Link device is detected and can be accessed properly. In Linux you might have to adept your udev rules accordingly:

> cat 49-stlinkv2.rules
# stm32 discovery boards, with onboard st/linkv2
# ie, STM32L, STM32F4.
# STM32VL has st/linkv1, which is quite different

SUBSYSTEMS=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="3748", \
    MODE:="0666", \
    SYMLINK+="stlinkv2_%n"

# If you share your linux system with other users, or just don't like the
# idea of write permission for everybody, you can replace MODE:="0666" with
# OWNER:="yourusername" to create the device owned by you, or with
# GROUP:="somegroupname" and mange access using standard unix groups.

> sudo cp 49-stlinkv2.rules /etc/udev/rules.d/
> sudo udevadm control --reload-rules
> sudo udevadm trigger

now replug the usb cable and flash.

Have a look at the 'Setting up udev rules' section in this README file if you need help.

Second you need to enable the standalone ST-Link mode of the discovery board by removing the two CN2 jumpers, found somewhere in the upper left part of the board. This disconnects the ST-Link programmer from the micro-controller part of the port and enables direct access through the pin-header CN3, also labled SWD.

This module supports the Serial Wire Debug (SWD) interface. To access the device the following four lines need to be connected with the STM32x-discovery board:

                 Airfy Beacon    STM32Fx-discovery
common ground:       GND <-----------> GND
supply voltage:      VDD <-----------> 3V
SWD clock:        SWDCLK <-----------> SWCLK (CN3, pin2)
SWD data I/O:      SWDIO <-----------> SWDIO (CN3, pin4)

The following image shows the wiring for an SWD flasher board:

Software

Debugging and programming this module works well with OpenOCD.

We suggest to use a fairly recent version, best use the upstream version from their git repository. Version Open On-Chip Debugger 0.9.0-dev-00184-g885f438 (2014-10-19-14:49) is reported to work.

Programming the Device

To program the Airfy Beacon, just go to your RIOT application and type:

make flash

and voila, the new firmware should be flashed onto your device.

Resetting the Device

As the Airfy Beacon module does not provide a reset button, RIOT includes a target to reset the board. To do that, just type

make reset

and your board will reboot.

Debugging the Device

The debugging setup comprises of two parts: a GDB server and a GDB client. To usual workflow is to start the GDB server first and then connect to it with some kind of front-end (e.g. command line, IDE, ...).

To start the GDB server, just type

make debug-server

This will start a local GDB server on port 3333.

If you are fine with working with the GDB command line client, you can start debugging your device by just typing

make debug

in a second terminal window. This will automatically connect to your previously opened GDB server and will also load your corresponding .elf file.

Alternatively you can configure your IDE (e.g. eclipse or similar) to connect directly to the GDB server. See here for more information on how to configure Eclipse

Program the device manually

For OpenOCD to work correctly, you need the following configuration file (which you can also find in RIOTDIR/boards/airfy-beacon/dist/openocd.cfg:

 $ cat RIOTDIR/boards/airfy-beacon/openocd.cfg
# nRF51822 Target
source [find interface/stlink-v2.cfg]

transport select hla_swd

set WORKAREASIZE 0x4000
source [find target/nrf51.cfg]

# use hardware reset, connect under reset
#reset_config srst_only srst_nogate

You can now program your device by doing the following:

1. start openocd with: openocd -d3 -f RIOTDIR/boards/airfy-beacon/dist/openocd.cfg
2. open a new terminal an connect with telnet: telnet 127.0.0.1 4444
3. do the following steps to flash (only use bank #0 starting from address 0):

> flash banks
#0 : nrf51.flash (nrf51) at 0x00000000, size 0x00040000, buswidth 1, chipwidth 1
#1 : nrf51.uicr (nrf51) at 0x10001000, size 0x000000fc, buswidth 1, chipwidth 1

> halt
target state: halted
target halted due to debug-request, current mode: Thread 
xPSR: 0x61000000 pc: 0x00000e1a msp: 0x20001b2c

> flash write_image erase PATH-TO-YOUR-BINARY/YOUR-BINARY.bin 0
wrote xxx bytes from file PATH-TO-YOUR-BINARY/YOUR-BINARY.bin in xx.yys (x.yyy KiB/s)

> reset

Debugging manually

First you have to start OpenOCD as described in the section above.

Then enter the following in a new terminal:

$ arm-none-eabi-gdb -tui "<your binary ELF>"

(gdb) target remote localhost:3333
Remote debugging using localhost:3333
0x000119ce in ?? ()

(gdb) load
Loading section .text, size 0x2284 lma 0x16000
Loading section .ARM.exidx, size 0x8 lma 0x18284
Loading section .data, size 0x458 lma 0x1828c
Loading section .jcr, size 0x4 lma 0x186e4
Transfer rate: x KB/sec, xxxx bytes/write.

(gdb) monitor reset halt
target state: halted
target halted due to debug-request, current mode: Thread 
xPSR: 0xc1000000 pc: 0x000006d0 msp: 0x000007c0

(gdb) break main
Breakpoint 3 at 0x123123: file ../main.c, line xx.
(gdb) continue
Continuing.

Using UART

The UART pins are configured in boards/airfy-beacon/include/periph_conf.h. The default values are PIN 17 and 18.

The default Baud rate is 115 200.