# MicroPython Port To The Nordic Semiconductor nRF Series

This is a port of MicroPython to the Nordic Semiconductor nRF series of chips.

## Supported Features

* UART
* SPI
* LEDs
* Pins
* ADC
* I2C
* PWM (nRF52 only)
* Temperature
* RTC (Real Time Counter. Low-Power counter)
* BLE support including:
  * Peripheral role on nrf51 targets
  * Central role and Peripheral role on nrf52 targets
  * _REPL over Bluetooth LE_ (optionally using WebBluetooth)
  * ubluepy: Bluetooth LE module for MicroPython
  * 1 non-connectable advertiser while in connection

## Tested Hardware

* nRF51
  * [micro:bit](http://microbit.org/)
  * PCA10000 (dongle)
  * PCA10001
  * PCA10028
  * PCA10031 (dongle)
  * [WT51822-S4AT](http://www.wireless-tag.com/wireless_module/BLE/WT51822-S4AT.html)
* nRF52832
  * [PCA10040](http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.nrf52%2Fdita%2Fnrf52%2Fdevelopment%2Fnrf52_dev_kit.html)
  * [Adafruit Feather nRF52](https://www.adafruit.com/product/3406)
  * [Thingy:52](http://www.nordicsemi.com/eng/Products/Nordic-Thingy-52)
  * [Arduino Primo](http://www.arduino.org/products/boards/arduino-primo)
  * [IBK-BLYST-NANO breakout board](https://www.crowdsupply.com/i-syst/blyst-nano)
  * [BLUEIO-TAG-EVIM BLYST Nano Sensor board](https://www.crowdsupply.com/i-syst/blyst-nano)
  * [uBlox EVK-NINA-B1](https://www.u-blox.com/en/product/evk-nina-b1)
* nRF52840
  * [PCA10056](http://www.nordicsemi.com/eng/Products/nRF52840-Preview-DK)
  * [PCA10059](https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF52840-Dongle)
  * [Particle Xenon](https://docs.particle.io/xenon/)
  * [nRF52840 MDK USB Dongle](boards/nrf52840-mdk-usb-dongle/README.md)
* nRF9160
  * [PCA10090](https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF9160-DK)
  * [Actinius Icarus](https://www.actinius.com/icarus)

## Compile and Flash

Prerequisite steps for building the nrf port:

    git clone <URL>.git micropython
    cd micropython
    make -C mpy-cross

By default, the PCA10040 (nrf52832) is used as compile target. To build and flash issue the following command inside the ports/nrf/ folder:

    make submodules
    make
    make deploy

Alternatively the target board could be defined:

    make submodules
    make BOARD=pca10040
    make BOARD=pca10040 deploy

## Compile without LTO enabled

As a space optimization, LTO (Link Time Optimization) has been enabled on all
targets in the nrf-port. The `-flto` linker flag can be toggled easily by using
the argument LTO when building. The example below shows how to disable LTO for
the compilation:

    make BOARD=pca10040 LTO=0

**Note**: There have been several issues with use of LTO in conjunction with
GNU ARM Embedded Toolchain 7.2.1/4Q17. It's recommended to use a toolchain after
this release, for example 7.3.1/2Q18 or 8.2.1/4Q18. The alternative would be to
build the target using the LTO=0 as described above.

## Compile and Flash with Bluetooth Stack

First prepare the bluetooth folder by downloading Bluetooth LE stacks and headers:

     ./drivers/bluetooth/download_ble_stack.sh

If the Bluetooth stacks has been downloaded, compile the target with the following command:

    make BOARD=pca10040 SD=s132

The **make sd** will trigger a flash of the bluetooth stack before that application is flashed. Note that **make sd** will perform a full erase of the chip, which could cause 3rd party bootloaders to also be wiped.

    make BOARD=pca10040 SD=s132 sd

Note: further tuning of features to include in bluetooth or even setting up the device to use REPL over Bluetooth can be configured in the `bluetooth_conf.h`.

## Compile with frozen modules

Frozen modules are Python modules compiled to bytecode and added to the firmware
image, as part of MicroPython. They can be imported as usual, using the `import`
statement. The advantage is that frozen modules use a lot less RAM as the
bytecode is stored in flash, not in RAM like when importing from a filesystem.
Also, frozen modules are available even when no filesystem is present to import
from.

To use frozen modules, put them in a directory (e.g. `freeze/`) and supply
`make` with the given directory. For example:

     make BOARD=pca10040 FROZEN_MPY_DIR=freeze

## Compile with freeze manifest

Freeze manifests can be used by definining `FROZEN_MANIFEST` pointing to a
`manifest.py`. This can either be done by a `make` invocation or by defining
it in the specific target board's `mpconfigboard.mk`.

For example:

    make BOARD=pca10040 FROZEN_MANIFEST=path/to/manifest.py

In case of using the target board's makefile, add a line similar to this:

    FROZEN_MANIFEST ?= $(BOARD_DIR)/manifest.py

In these two examples, the manual `make` invocation will have precedence.

## Enable MICROPY_VFS_FAT
As the `oofatfs` module is not having header guards that can exclude the implementation compile time, this port provides a flag to enable it explicitly. The MICROPY_VFS_FAT is by default set to 0 and has to be set to 1 if `oofatfs` files should be compiled. This will be in addition of setting `MICROPY_VFS` in mpconfigport.h.

For example:

     make BOARD=pca10040 MICROPY_VFS_FAT=1

## Enable MICROPY_VFS_LFS1 or MICROPY_VFS_LFS2

In order to enable `littlefs` as device flash filesystem, `MICROPY_VFS_LFS1`
or `MICROPY_VFS_LFS2` can be set. This will be in addition of setting
`MICROPY_VFS` in mpconfigport.h or mpconfigboard.h.

For example:

    make BOARD=pca10056 MICROPY_VFS_LFS2=1

## Set file system size

The size of the file system on the internal flash is configured by the linker
script parameter `_fs_size`. This can either be overriden by the linker script
or dynamically through the makefile. By seting a value to the `FS_SIZE`.
The number will be passed directly to the linker scripts in order to calculate
the start and end of the file system. Note that the parameter value must be in
linker script syntax as it is passed directly.

For example, if we want to override the default file system size set by the
linker scripts to use 256K:

    make BOARD=pca10056 MICROPY_VFS_LFS2=1 FS_SIZE=256K

Also note that changing this size between builds might cause loss of files
present from a previous firmware as it will format the file system due to a new
location.

## Target Boards and Make Flags

Target Board (BOARD) | Bluetooth Stack (SD)    | Bluetooth Support      | Bootloader     | Default Flash Util
---------------------|-------------------------|------------------------|----------------|-------------------
microbit             | s110                    | Peripheral             |                | [PyOCD](#pyocdopenocd-targets)
pca10000             | s110                    | Peripheral             |                | [Segger](#segger-targets)
pca10001             | s110                    | Peripheral             |                | [Segger](#segger-targets)
pca10028             | s110                    | Peripheral             |                | [Segger](#segger-targets)
pca10031             | s110                    | Peripheral             |                | [Segger](#segger-targets)
wt51822_s4at         | s110                    | Peripheral             |                | Manual, see [datasheet](https://4tronix.co.uk/picobot2/WT51822-S4AT.pdf) for pinout
pca10040             | s132                    | Peripheral and Central |                | [Segger](#segger-targets)
feather52            | s132                    | Peripheral and Central |                | Manual, SWDIO and SWCLK solder points on the bottom side of the board
arduino_primo        | s132                    | Peripheral and Central |                | [PyOCD](#pyocdopenocd-targets)
ibk_blyst_nano       | s132                    | Peripheral and Central |                | [IDAP](#idap-midap-link-targets)
idk_blyst_nano       | s132                    | Peripheral and Central |                | [IDAP](#idap-midap-link-targets)
blueio_tag_evim      | s132                    | Peripheral and Central |                | [IDAP](#idap-midap-link-targets)
evk_nina_b1          | s132                    | Peripheral and Central |                | [Segger](#segger-targets)
pca10056             | s140                    | Peripheral and Central |                | [Segger](#segger-targets)
pca10059             | s140                    | Peripheral and Central | OpenBootloader | [nrfutil](#nrfutil-targets)
particle_xenon       | s140                    | Peripheral and Central |                | [Black Magic Probe](#black-magic-probe-targets)
nrf52840-mdk-usb-dongle | s140                 | Peripheral and Central | OpenBootloader | [nrfutil](#nrfutil-targets)
pca10090             | None (bsdlib.a)         | None (LTE/GNSS)        |                | [Segger](#segger-targets)
actinius_icarus      | None (bsdlib.a)         | None (LTE/GNSS)        |                | [Segger](#segger-targets)

## IDAP-M/IDAP-Link Targets

Install the necessary tools to flash and debug using IDAP-M/IDAP-Link CMSIS-DAP Debug JTAG:

[IDAPnRFProg for Linux](https://sourceforge.net/projects/idaplinkfirmware/files/Linux/IDAPnRFProg_1_7_190320.zip/download)
[IDAPnRFProg for OSX](https://sourceforge.net/projects/idaplinkfirmware/files/OSX/IDAPnRFProg_1_7_190320.zip/download)
[IDAPnRFProg for Windows](https://sourceforge.net/projects/idaplinkfirmware/files/Windows/IDAPnRFProg_1_7_190320.zip/download)


## Segger Targets

Install the necessary tools to flash and debug using Segger:

[JLink Download](https://www.segger.com/downloads/jlink#)

[nrfjprog Download](https://www.nordicsemi.com/Software-and-Tools/Development-Tools/nRF5-Command-Line-Tools/Download#infotabs)

note: On Linux it might be required to link SEGGER's `libjlinkarm.so` inside nrfjprog's folder.

## PyOCD/OpenOCD Targets

Install the necessary tools to flash and debug using OpenOCD:

    sudo apt-get install openocd
    sudo pip install pyOCD

## Black Magic Probe Targets

This requires no further dependencies other than `arm-none-eabi-gdb`.

`make deploy` will use gdb to load and run new firmware. See
[this guide](https://github.com/blacksphere/blackmagic/wiki/Useful-GDB-commands)
for more tips about using the BMP with GDB.

## nRFUtil Targets

Install the necessary Python packages that will be used for flashing using the bootloader:

    sudo pip install nrfutil
    sudo pip install intelhex

The `intelhex` provides the `hexmerge.py` utility which is used by the Makefile
to trim of the MBR in case SoftDevice flashing is requested.

`nrfutil` as flashing backend also requires a serial port paramter to be defined
in addition to the `deploy` target of make. For example:

    make BOARD=nrf52840-mdk-usb-dongle NRFUTIL_PORT=/dev/ttyACM0 deploy

If the target device is connected to `/dev/ttyACM0` serial port, the
`NRFUTIL_PORT` parameter to make can be elided as it is the default serial
port set by the Makefile.

When enabling Bluetooth LE, as with the other flash utils, the SoftDevice
needs to be flashed in the first firmware update. This can be done by issuing
the `sd` target instead of `deploy`. For example:

    make BOARD=nrf52840-mdk-usb-dongle SD=s140 NRFUTIL_PORT=/dev/ttyACM0 sd

## Bluetooth LE REPL

The port also implements a BLE REPL driver. This feature is disabled by default, as it will deactivate the UART REPL when activated. As some of the nRF devices only have one UART, using the BLE REPL free's the UART instance such that it can be used as a general UART peripheral not bound to REPL.

The configuration can be enabled by editing the `bluetooth_conf.h` and set `MICROPY_PY_BLE_NUS` to 1.

When enabled you have different options to test it:
* [NUS Console for Linux](https://github.com/tralamazza/nus_console) (recommended)
* [WebBluetooth REPL](https://aykevl.nl/apps/nus/) (experimental)

Other:
* nRF UART application for IPhone/Android

WebBluetooth mode can also be configured by editing `bluetooth_conf.h` and set `BLUETOOTH_WEBBLUETOOTH_REPL` to 1. This will alternate advertisement between Eddystone URL and regular connectable advertisement. The Eddystone URL will point the phone or PC to download [WebBluetooth REPL](https://aykevl.nl/apps/nus/) (experimental), which subsequently can be used to connect to the Bluetooth REPL from the PC or Phone browser.


## Pin numbering scheme for nrf52840-based boards

Software Pins 0-31 correspond to physical pins 0.x and software Pins 32-47
correspond to physical pins 1.x.

Example:
`Pin(47)` would be 1.15 on the PCA10059
