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SAMD21 M0-Mini & CircuitPython

2021-02-24T18:00:00+00:00

SAMD21 M0-Mini is a cheap clone of Arduino M0-mini sold under various names and sellers. RobotDyn offers the same board with and without CircuitPython support. Accidentally I ordered units without one and the following is how to get UF2 bootloader and CircuitPython working on these devices. If you want to skip the following, make sure you order a board with CircuitPython. It will cost you a few more bucks, RobotDyn offers both.

Get the latest Arduino IDE. It should have the correct USB drivers included. Make sure you have samd21 as additional boards installed. The IDE should do it automatically or prompt you.
Download the latest .ino file to update the bootloader. At the of writing it's update-bootloader-zero-v3.13.0.ino.
Open the .ino file and select the correct port. Board: Arduino SAMD (32 bit ARM), programmer: Atmel-SAM-ICE. Compile and upload. An USB disk named ZEROBOOT should appear.
Download the latest correct version of CircuitPython. At the time of writing adafruit-circuitpython-sparkfun_samd21_mini-en_US-6.1.0.uf2. Copy the uf2 file to the root of the ZEROBOOT disk. An USB disk named CIRCUITPY should mount after a few seconds.
As a default, CircuitPython looks for code.py at the root of the USB and executes the code within the file automatically when the board starts up or resets.

Create code.py and test if the board's integrated LED starts blinking fast:

import board
import digitalio
import time

led = digitalio.DigitalInOut(board.D13)
led.direction = digitalio.Direction.OUTPUT

while True:
    led.value = True
    time.sleep(1)
    led.value = False
    time.sleep(0.2)
    led.value = True
    time.sleep(0.2)
    led.value = False
    time.sleep(0.2)

You can always unmount CIRCUITPY and go back to bootloader by double tapping the only button of the board.

More useful information about the board by Bryan Lavery.

i3 transparent placeholder

2020-08-20T21:30:00+01:00

i3 does have i3 open command to open blank/empty container but at least for me it draws weird container borders on desktop and in general is undocumented and unreliable.

To get over it I use Python's tkinter to make a simple 'gui' and use main windows alpha attribute to make it completely transparent.

You can drop a python program in your config folder, something like that:

#!/usr/bin/env python3

import sys
try:
    from tkinter import Tk
    tkinterExist = True
except ModuleNotFoundError:
    tkinterExist = False
    print('Install tkinter module (possibly apt install python3-tk)')

if tkinterExist:
    try:
        args = sys.argv[1]
    except:
        args = 0
    print('Alpha level: {0}'.format(args))

    root = Tk()
    root.wait_visibility(root)
    root.wm_attributes('-alpha', args)
    root.mainloop()

And bind it to some key, mod+o in my case:

bindsym $mod+o exec bash -c 'python3 ~/.config/i3/placeholder.py'

Works like charm, even takes a parameter for the opacity level, defaulting to 0. placeholder.py 0.5 for semi transparency.

Tasmotized Sonoff IFan03 and HASS

2020-07-06T11:00:00+01:00

Sonoff IFan03 is a cheap little device for controlling a ceiling fan that you can manage over WiFi or 433MHz radio. Thankfully, it's very easy to flash open source Tasmota on it.

The case is not glued together, easy to open and put back together by bending the sides.

The pins necessary for flashing are marked, you can solder 2.45mm header and leave it, the case closes just fine afterwards. When you're ready to flash hold down the large white button that you use for RF pairing while you boot up and release after 5 seconds.

It doesn't have a spare GPIO for sensor(s). In most cases it's not worth it, but you can use RX/TX as GPIO if you turn serial logging off completely.

I used ft232r USB to serial UART interface with Tasmotizer flashing tool for Tasmota. Below the wiring.

HASS

Tasmota already has a template for IFan03 and you can communicate with Home Assistant over MQTT. In your configuration.yaml file you need to setup a template something like this.

fan:
  - platform: mqtt
    name: "ifan03"
    state_topic: "ifan03-1/stat/RESULT"
    speed_state_topic: "ifan03-1/stat/RESULT"
    state_value_template: >
        {% if value_json.FanSpeed is defined -%}
          {% if value_json.FanSpeed == 0 -%}0{%- elif value_json.FanSpeed > 0 -%}1{%- endif %}
        {%- else -%}
          {% if states.fan.ifan03.state == 'off' -%}0{%- elif states.fan.ifan03.state == 'on' -%}1{%- endif %}
        {%- endif %}
    speed_value_template: "{{ value_json.FanSpeed }}"
    availability_topic: ifan03-1/tele/LWT
    payload_available: Online
    payload_not_available: Offline
    speed_command_topic: "ifan03-1/cmnd/FanSpeed"
    payload_low_speed: "1"
    payload_medium_speed: "2"
    payload_high_speed: "3"
    command_topic: "ifan03-1/cmnd/FanSpeed"
    payload_off: "0"
    payload_on: "1"
    qos: 1
    speeds:
      - low
      - medium
      - high
  - platform: mqtt
    name: "ifan03_light"
    state_topic: "ifan03-1/tele/STATE"
    value_template: "{{ value_json.POWER }}"
    command_topic: "ifan03-1/cmnd/POWER"
    availability_topic: "ifan03-1/tele/LWT"
    qos: 1
    payload_on: "ON"
    payload_off: "OFF"
    payload_available: "Online"
    payload_not_available: "Offline"

Make sure your MQTT topics correspond to your setup.

As of current version 0.112.3 Home Assistant's Lovelace UI doesn't really have a proper card to represent a fan control. The device is basically three switches (speeds), with default UI you can use horizontal stack card with three entity buttons inside.

cards:
  - entity: fan.ifan03
    name: Low
    show_icon: true
    show_name: true
    tap_action:
      action: call-service
      service: fan.set_speed
      service_data:
        entity_id: fan.ifan03
        speed: 1
    type: entity-button
  - entity: fan.ifan03
    name: Normal
    show_icon: true
    show_name: true
    tap_action:
      action: call-service
      service: fan.set_speed
      service_data:
        entity_id: fan.ifan03
        speed: 2
    type: entity-button
  - entity: fan.ifan03
    name: Fast
    show_icon: true
    show_name: true
    tap_action:
      action: call-service
      service: fan.set_speed
      service_data:
        entity_id: fan.ifan03
        speed: 3
    type: entity-button
  - entity: fan.ifan03
    icon: 'mdi:stop-circle-outline'
    name: 'Off'
    show_icon: true
    show_name: true
    tap_action:
      action: call-service
      service: fan.set_speed
      service_data:
        entity_id: fan.ifan03
        speed: 0
    type: entity-button
type: horizontal-stack

Which would correspond to something like this.

Or you can use a custom card I made for myself, downloadable from github.

i3, XF86 multimedia keys and xdotool

2018-04-16T13:55:00+01:00

Chromium (and Google Chrome) does not let you change the default keyboard shortcuts. Because they decided to remove backspace as a go back in history because it was confusing, the only shortcut left to navigate back is Alt+Right.

Alt is my Mod key and I prefer to navigate between windows with arrows, therefor i3 overwrites Chromium's Alt+Right shortcut.

There are extensions to change keyboard shortcuts, but they all work as injecting scripts to every page. Sometimes it doesn't work and it adds a bloat. My solution was to bind $mod+b to XF86 keyboard shortcut using xdotool. I'm sure there is a better way but I prefer this to adding extensions to my browser.

bindsym --release $mod+b exec --no-startup-id xdotool key --clearmodifiers XF86Back