IoT Kernel#

The IoT Kernel is a specialized Jupyter kernel that evaluates MicroPython code on connected microcontrollers. Features include:

  • discover and connect to wired and wireless microcontrollers (%discover and %connect)

  • synchronize files with the host (%rsync)

  • softreset (%softreset)

  • evaluate code on the host (%%host)

  • exchange variables between microcontrollers and the host (%store)

  • access the shell (%%bash)

  • access other services of ide49, e.g. cross-compilers (%%service)

Magics#

Many of these features are accessed via magics. %lsmagic lists available magics.

%lsmagic
Hide code cell output 
Line Magic:    -h shows help (e.g. %discover -h)
  %cat         Output contents of file stored on microcontroller
  %cd          Change current working directory on host
  %connect     Connect to device by name, uid, or url
  %cp          Copy files between host and microcontroller
  %discover    Discover available devices
  %gettime     Query microcontroller time
  %hardreset   Reset microcontroller by calling 'machine.reset()'. 
  %info        Summary about connected device
  %loglevel    Set logging level.
  %lsmagic     List all magic functions
  %mkdirs      Create all directories on the microcontroller, as needed (similar to Linux mkdir -p)
  %name        Print the name of the currently connected device
  %pip         Install packages from PyPi
  %rdiff       Show differences between microcontroller and host directories
  %register    Register device
  %rlist       List files on microcontroller
  %rm          Remove files on microcontroller
  %rsync       Synchronize microcontroller to host directories
  %softreset   Reset microcontroller.
  %store       Copy variables between microcontroller and storage
  %synctime    Synchronize microcontroller time to host
  %uid         Print the uid of the currently connected device
  %unregister  Unregister device
  %upip        Install MicroPython packages
  !            Pass line to bash shell for evaluation

Cell Magic:    -h shows help (e.g. %%connect -h)
  %%bash       Pass cell to bash shell for evaluation
  %%connect    Generalization of %connect to run code on several devices sequentially
  %%service    Send code to bash in named container for execution
  %%ssh        Pass cell body to ssh.
  %%writefile  Write cell contents to file

The -h option on any magic returns additional information. E.g.

%discover -h

usage: %discover [-h] [-a] [-v]

Discover available devices

optional arguments:
  -h, --help     show this help message and exit
  -a, --all      list all devices connected to USB ports
  -v, --verbose  show uid


%%host -h

usage: %%host [-h]

Pass cell to host (cPython) for evaluation.

optional arguments:
  -h, --help  show this help message and exit

MicroPython#

At any one time, the kernel is connected to one (or no) microcontroller. Code typed into Jupyter cells is sent to the “connected” microcontroller for evaluation. The %discover magic scans USB ports and listens for advertisements sent over the internet. For each device to which connection is successful (verified by connecting to the device and running a short piece of code), discover shows the device name, URL, and, optionally, UID (-v flag). Device names are specified in configuration files).

Note: Use a powered USB hub to reliably connect more than one microcontroller (especially power hungry ESP32’s) to a Raspberry Pi!

%discover

test-esp32  ws://10.39.40.135:8266  
samd51      serial:///dev/ttyACM0   
stm32       serial:///dev/ttyACM1   
test-esp32  serial:///dev/ttyUSB2   
pico        serial:///dev/ttyUSB0   
nrf52840    serial:///dev/ttyACM2   
huzzah32    serial:///dev/ttyUSB1

The test-esp32 is available both over USB (serial:///dev/ttyUSB2) and wirelessly via webrepl (ws://10.39.40.135:8266).

%connect test-esp32 ws

for i in range(5): print(i, i**20)

Connected to test-esp32 @ ws://10.39.40.135:8266
0 0
1 1
2 1048576
3 3486784401
4 1099511627776

Connection to a device is maintained until changed. Hint: open several notebooks to connect to more than one device simultaneously.

The %%connect cell magic runs code sequentially on one or more processors:

%%connect --all --host

import sys
print("{:18}   ({})".format(sys.platform, sys.implementation.name))
Hide code cell output 

----- HOST

linux                (cpython)

----- test-esp32

esp32                (micropython)

----- samd51

MicroChip SAMD51     (circuitpython)

----- stm32

pyboard              (micropython)

----- test-esp32

esp32                (micropython)

----- pico

esp32                (micropython)

----- nrf52840

nRF52840             (circuitpython)

----- huzzah32

esp32                (micropython)

The %softreset magic resets the MicroPython interpreter, freeing assigned variables and deallocating most peripherals:

%name

a = 5
print(a)
%softreset
print("this will fail ...")
print(a)

test-esp32
5

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!   softreset ...     !!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

this will fail ...

Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
NameError: name 'a' isn't defined

Consult the documentation for device configuration for automated file upload.