diff --git a/.travis.yml b/.travis.yml
index b630a5e5..79b24873 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,5 @@
 env:
   global:
-    # - ARDUINO_IDE_VERSION="1.8.13"
   matrix:
     # see https://github.com/arduino/Arduino/blob/master/build/shared/manpage.adoc#options
     # and https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5-3rd-party-Hardware-specification#boardstxt
@@ -30,19 +29,7 @@ addons:
       - python3-setuptools
 
 before_install:
-  # install Arduino
-  # - wget https://downloads.arduino.cc/arduino-$ARDUINO_IDE_VERSION-linux64.tar.xz
-  # - tar xf arduino-$ARDUINO_IDE_VERSION-linux64.tar.xz
-  # - mv arduino-$ARDUINO_IDE_VERSION $HOME/arduino-ide
-  # - export PATH=$PATH:$HOME/arduino-ide
-  # firewall Arduino IDE noise (https://github.com/per1234/arduino-ci-script/issues/1#issuecomment-504158113)
-  # - sudo iptables -P INPUT DROP
-  # - sudo iptables -P FORWARD DROP
-  # - sudo iptables -P OUTPUT ACCEPT
-  # - sudo iptables -A INPUT -i lo -j ACCEPT
-  # - sudo iptables -A OUTPUT -o lo -j ACCEPT
-  # - sudo iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
-
+  # install Arduino CLI
   - curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | sh
   - export PATH=$PATH:$PWD/bin
 
@@ -65,85 +52,66 @@ before_install:
 
     elif [[ "$BOARD" =~ "esp8266:esp8266:" ]]; then
       export BUILD_EXAMPLES=false;
-      # arduino --pref "boardsmanager.additional.urls=http://arduino.esp8266.com/stable/package_esp8266com_index.json" --save-prefs 2>&1;
-      # arduino --install-boards esp8266:esp8266;
       arduino-cli core update-index --additional-urls http://arduino.esp8266.com/stable/package_esp8266com_index.json;
-      arduino-cli core install esp8266:esp8266;
+      arduino-cli core install esp8266:esp8266 --additional-urls http://arduino.esp8266.com/stable/package_esp8266com_index.json;
       export SKIP_PAT='(HTTP|MQTT).*ino';
 
     elif [[ "$BOARD" =~ "esp32:esp32:" ]]; then
       export BUILD_EXAMPLES=false;
-      # arduino --pref "boardsmanager.additional.urls=https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json" --save-prefs 2>&1;
-      # arduino --install-boards esp32:esp32;
       arduino-cli core update-index --additional-urls https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json;
-      arduino-cli core install esp32:esp32;
+      arduino-cli core install esp32:esp32 --additional-urls https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json;
 
     elif [[ "$BOARD" =~ "STM32:stm32:" ]]; then
       export BUILD_EXAMPLES=false;
-      # arduino --pref "boardsmanager.additional.urls=https://github.com/stm32duino/BoardManagerFiles/raw/master/STM32/package_stm_index.json" --save-prefs 2>&1;
-      # arduino --install-boards STM32:stm32;
       arduino-cli core update-index --additional-urls https://github.com/stm32duino/BoardManagerFiles/raw/master/STM32/package_stm_index.json;
-      arduino-cli core install STM32:stm32;
+      arduino-cli core install STM32:stm32 --additional-urls https://github.com/stm32duino/BoardManagerFiles/raw/master/STM32/package_stm_index.json;
 
     elif [[ "$BOARD" =~ "arduino:samd:" ]]; then
       export BUILD_EXAMPLES=false;
       arduino-cli core update-index;
-      # arduino --install-boards arduino:samd;
       arduino-cli core install arduino:samd;
 
     elif [[ "$BOARD" =~ "arduino:sam:" ]]; then
       export BUILD_EXAMPLES=false;
       arduino-cli core update-index;
-      # arduino --install-boards arduino:sam;
       arduino-cli core install arduino:sam;
 
     elif [[ "$BOARD" =~ "adafruit:nrf52:" ]]; then
       pip3 install --user adafruit-nrfutil;
       export BUILD_EXAMPLES=false;
-      # arduino --pref "boardsmanager.additional.urls=https://www.adafruit.com/package_adafruit_index.json" --save-prefs 2>&1;
-      # arduino --install-boards adafruit:nrf52;
       arduino-cli core update-index --additional-urls https://www.adafruit.com/package_adafruit_index.json;
-      arduino-cli core install adafruit:nrf52;
+      arduino-cli core install adafruit:nrf52 --additional-urls https://www.adafruit.com/package_adafruit_index.json;
 
     elif [[ "$BOARD" =~ "Intel:arc32:" ]]; then
       export BUILD_EXAMPLES=false;
       arduino-cli core update-index;
-      # arduino --install-boards Intel:arc32;
       arduino-cli core install Intel:arc32;
 
     elif [[ "$BOARD" =~ "arduino:megaavr:" ]]; then
       export BUILD_EXAMPLES=false;
       arduino-cli core update-index;
-      # arduino --install-boards arduino:megaavr;
       arduino-cli core install arduino:megaavr;
 
     elif [[ "$BOARD" =~ "SparkFun:apollo3:" ]]; then
       export BUILD_EXAMPLES=false;
-      # arduino --pref "boardsmanager.additional.urls=https://raw.githubusercontent.com/sparkfun/Arduino_Boards/master/IDE_Board_Manager/package_sparkfun_index.json" --save-prefs 2>&1;
-      # arduino --install-boards SparkFun:apollo3;
       arduino-cli core update-index --additional-urls https://raw.githubusercontent.com/sparkfun/Arduino_Boards/master/IDE_Board_Manager/package_sparkfun_index.json;
-      arduino-cli core install SparkFun:apollo3;
+      arduino-cli core install SparkFun:apollo3 --additional-urls https://raw.githubusercontent.com/sparkfun/Arduino_Boards/master/IDE_Board_Manager/package_sparkfun_index.json;
 
     elif [[ "$BOARD" =~ "arduino:mbed:" ]]; then
       export BUILD_EXAMPLES=false;
       arduino-cli core update-index;
-      # arduino --install-boards arduino:mbed;
       arduino-cli core install arduino:mbed;
       export SKIP_PAT='(HTTP|MQTT).*ino';
 
     elif [[ "$BOARD" =~ "stm32duino:STM32F1:" ]]; then
       export BUILD_EXAMPLES=false;
-      # arduino --pref "boardsmanager.additional.urls=http://dan.drown.org/stm32duino/package_STM32duino_index.json" --save-prefs 2>&1;
-      # arduino --install-boards stm32duino:STM32F1;
       arduino-cli core update-index --additional-urls http://dan.drown.org/stm32duino/package_STM32duino_index.json;
-      arduino-cli core install stm32duino:STM32F1;
+      arduino-cli core install stm32duino:STM32F1 --additional-urls http://dan.drown.org/stm32duino/package_STM32duino_index.json;
 
     elif [[ "$BOARD" =~ "adafruit:samd:" ]]; then
       export BUILD_EXAMPLES=false;
-      # arduino --pref "boardsmanager.additional.urls=https://www.adafruit.com/package_adafruit_index.json" --save-prefs 2>&1;
-      # arduino --install-boards adafruit:samd;
       arduino-cli core update-index --additional-urls https://www.adafruit.com/package_adafruit_index.json
-      arduino-cli core install adafruit:samd;
+      arduino-cli core install adafruit:samd --additional-urls https://www.adafruit.com/package_adafruit_index.json
 
     elif [[ "$BOARD" =~ "arduino-beta:mbed:" ]]; then
       export BUILD_EXAMPLES=false;