diff --git a/.travis.yml b/.travis.yml
index 1857565..ea71553 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,22 +9,29 @@ cache:
         - "~/.platformio"
 
 env:
-    - PLATFORMIO_CI_SRC=examples/ChangeUID/ChangeUID.ino
-    - PLATFORMIO_CI_SRC=examples/DumpInfo/DumpInfo.ino
-    - PLATFORMIO_CI_SRC=examples/firmware_check/firmware_check.ino
-    - PLATFORMIO_CI_SRC=examples/FixBrickedUID/FixBrickedUID.ino
-    - PLATFORMIO_CI_SRC=examples/MifareClassicValueBlock/MifareClassicValueBlock.ino
-    - PLATFORMIO_CI_SRC=examples/ReadAndWrite/ReadAndWrite.ino
-    - PLATFORMIO_CI_SRC=examples/ReadUidMultiReader/ReadUidMultiReader.ino
-    - PLATFORMIO_CI_SRC=examples/rfid_default_keys/rfid_default_keys.ino
-    - PLATFORMIO_CI_SRC=examples/rfid_write_personal_data/rfid_write_personal_data.ino
-    - PLATFORMIO_CI_SRC=examples/Ntag216_AUTH/Ntag216_AUTH.ino
-    - PLATFORMIO_CI_SRC=examples/ReadNUID/ReadNUID.ino
-    - PLATFORMIO_CI_SRC=examples/servo_motor/servo_motor.ino
-    - PLATFORMIO_CI_SRC=examples/RFID-Cloner/RFID-Cloner.ino
+    # add examples here and define which boards should be tested (only compile test)
+    - PLATFORMIO_CI_SRC=examples/ChangeUID/ChangeUID.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/DumpInfo/DumpInfo.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/firmware_check/firmware_check.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/FixBrickedUID/FixBrickedUID.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/MifareClassicValueBlock/MifareClassicValueBlock.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/ReadAndWrite/ReadAndWrite.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/ReadUidMultiReader/ReadUidMultiReader.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/rfid_default_keys/rfid_default_keys.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/rfid_write_personal_data/rfid_write_personal_data.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/Ntag216_AUTH/Ntag216_AUTH.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/ReadNUID/ReadNUID.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
+    - PLATFORMIO_CI_SRC=examples/servo_motor/servo_motor.ino TESTBOARD=arduino_avr,teensy
+    - PLATFORMIO_CI_SRC=examples/RFID-Cloner/RFID-Cloner.ino TESTBOARD=arduino_avr,arduino_arm,teensy,esp
 
 install:
     - pip install -U platformio
 
 script:
-    - platformio ci --lib=. --board=uno --board=megaatmega1280 --board=teensy31
+    # short the string comparison
+    - stringContain() { [ -z "${2##*$1*}" ]; }
+    # selectable board tests @Rotzbua
+    - board="arduino_avr";  if stringContain "$board" "$TESTBOARD"; then echo "check board $board"; platformio ci --lib=. --board=uno --board=megaatmega1280; else echo "skip board test of $board"; fi
+    - board="arduino_arm";  if stringContain "$board" "$TESTBOARD"; then echo "check board $board"; platformio ci --lib=. --board=due --board=zero; else echo "skip board test of $board"; fi
+    - board="teensy";  if stringContain "$board" "$TESTBOARD"; then echo "check board $board"; platformio ci --lib=. --board=teensy31; else echo "skip board test of $board"; fi
+    - board="esp";  if stringContain "$board" "$TESTBOARD"; then echo "check board $board"; platformio ci --lib=. --board=d1_mini; else echo "skip board test of $board"; fi
diff --git a/README.rst b/README.rst
index 7555ec0..87ec696 100644
--- a/README.rst
+++ b/README.rst
@@ -13,8 +13,14 @@ Interface (SPI) interface.
 Set the UID, write to sector 0, and unbrick Chinese UID changeable MIFARE cards.
 
 
-.. _pin layout:
+.. _compatible boards:
+Compatible boards
+----------
 
+This library is compatible to Teensy and ESP8266, but not all examples are available for every board. Also you have to change pins, see `pin layout`_.
+
+
+.. _pin layout:
 Pin Layout
 ----------
 
@@ -43,6 +49,7 @@ The following table shows the typical pin layout used:
 .. [3] The SDA pin might be labeled SS on some/older MFRC522 boards. 
 
 
+.. _hardware:
 Hardware
 --------
 
@@ -133,6 +140,7 @@ Troubleshooting
   #. Hardware may be corrupted, most products are from china and sometimes the quality is really poor. Contact your seller.
   #. Newer versions of Mifare cards like DESFire/Ultralight maybe not work according to missing authentification, see `security`_ or different `protocol`_.
 
+
 * **My mobile phone doesn't recognize the MFRC522** or **my MFRC522 can't read data from other MFRC522**
 
   #. Card simmulation is not supported.
@@ -146,6 +154,7 @@ Troubleshooting
   #. If hardware: buy a more expensive like PN532 (supports NFC and many more, but costs about $15)
 
 
+.. _license:
 License
 -------
 This is free and unencumbered software released into the public domain.