4 files changed, 47 insertions, 29 deletions
diff --git a/assignments/blink-a-led/blink-a-led.md b/assignments/blink-a-led/blink-a-led.md
index a08bc4e..72bbb9c 100644
--- a/assignments/blink-a-led/blink-a-led.md
+++ b/assignments/blink-a-led/blink-a-led.md
@@ -6,10 +6,19 @@ Check that your local environment is working properly.
 
 ## Configure the Arduino IDE
 
-Under *Tools* -> *Board* make sure that "NodeMCU 1.0 (ESP-12E Module)"
-is available and selected.
+1. Make sure the "ESP8266" core is installed. If it is not installed
+   follow the installation instructions:
 
-Create a new sketch with *File* -> *New* and compile it with *ctrl-R*.
+   [https://github.com/esp8266/Arduino#installing-with-boards-manager](https://github.com/esp8266/Arduino#installing-with-boards-manager)
+
+1. Under *Tools* -> *Board* make sure that "NodeMCU 1.0 (ESP-12E
+   Module)" is available and selected.
+
+1. Select the correct serial port: *Tools -> Port*.
+
+1. Select the highest upload speed: *Tools -> Upload Speed*.
+
+1. Create a new sketch with *File* -> *New* and compile it with *ctrl-R*.
 
 ## Step 1
 
@@ -24,7 +33,7 @@ orientation is not important, but the LED's orientation is important.
 
 ## Step 2
 
-Implement `setup()` and `loop()`. In `setup()` configure the LED pin and blink the LED in `loop()`.
+Implement `setup()` and `loop()`: In `setup()` configure the LED pin and blink the LED in `loop()`.
 
 Use these functions:
 
@@ -32,9 +41,14 @@ Use these functions:
 Serial.begin(115200);
 Serial.println(string);
 
+// Pin is D1/D2/D..
+// mode is INPUT or OUTPUT
 pinMode(pin, mode);
-digitalWrite(pin, state); // HIGH or LOW
-delay();
+
+// HIGH or LOW
+digitalWrite(pin, state);
+
+delay(ms);
 ~~~
 
 ## Tips
diff --git a/assignments/blink-a-led/blink-a-led.pdf b/assignments/blink-a-led/blink-a-led.pdf
index da370c4..655f964 100644
--- a/assignments/blink-a-led/blink-a-led.pdf
+++ b/assignments/blink-a-led/blink-a-led.pdf
diff --git a/assignments/mqtt-with-button/mqtt-with-button.md b/assignments/mqtt-with-button/mqtt-with-button.md
index c825615..30defc8 100644
--- a/assignments/mqtt-with-button/mqtt-with-button.md
+++ b/assignments/mqtt-with-button/mqtt-with-button.md
@@ -6,6 +6,11 @@
 * Publish a message when a button is pressed.
 * Subscribe to a topic to control the LED
 
+## Preparation
+
+* Install the *PubSubClient* library. Use the library manager under
+  *Sketch -> Include library -> Library Manager* to install it.
+
 ## Step 1
 
 Wire up this schematic on the bread board:
@@ -16,10 +21,8 @@ Wire up this schematic on the bread board:
 
 # Step 2
 
-* Tip: change upload speed to max.
-
-* Read button in `loop()`. If the button's state changes, print a
-  message.
+* Read button's value inside `loop()`. If the button's state changes,
+  print a message.
 
 *Note:* reading the button in a busy loop is not really a best
 practice as it uses lots of energy. Instead use the `attachInterrupt`.
@@ -29,34 +32,35 @@ practice as it uses lots of energy. Instead use the `attachInterrupt`.
 * Connect to the Wi-Fi network
 * Connect to MQTT broker
 
+See the slides for example code.
+
 # Step 4
 
-* Publish a message on button press on the topic
+* Create a subscription for `ndc/$device-id/#` with HiveMQ's web ui:
+  http://www.hivemq.com/demos/websocket-client/
+* Publish a message when the button is pressed on the topic
   `ndc/$device-id/button`
 
 # Step 5 (Bonus)
 
-Subscripe to a topic and do something with the led.
-
-* Subscribe to the topic you're publishing to.
-
-* Subscribe to the topic `ndc/$device-id/led`.
- 
-* Use the value to for example turn the LED on/off, or change the
-  LED's blinking pattern.
+*Feel free to be creative here.*
 
-## Tips
+The other useful half of MQTT is subscribing to topics and reacting to
+messages. Here are some example things you can do:
 
-To generate a client id make something with `ESP.getChipId()`{.cpp}
+* Subscribe to the topic you're publishing to and change the state of
+  the LED when the button is pressed. This will give you a very
+  complicated and brittle way of toggling a LED.
 
-Creating a `String` from a number:
+* In `loop` blink the led. Subscribe to another topic (for example
+  `ndc/$device-id/frequency`), and use the value as a way to control
+  the blink rate.
 
-* `String(123) => "123"`{.cpp}
-* Hex formatted: `String(0x123abc, HEX) => "123abc"`{.cpp}
+# Step 6 (Strech goal)
 
-Some APIs require "plain C strings" aka a `char *`{.cpp}. They can be
-converted with `String::c_str()`:
+Use a last will message to indicate if the device is online or not.
 
-~~~.c++
-char *cStr = myString.c_str();
-~~~
+* When connecting, include a last will message with topic
+  `ndc/$device-id/online` and payload `0`.
+* After a successfull connection, publish a similar message with the
+  payload `1`. Observe what happens when you unplug the device.
diff --git a/assignments/mqtt-with-button/mqtt-with-button.pdf b/assignments/mqtt-with-button/mqtt-with-button.pdf
index 8fcccf7..ccb511e 100644
--- a/assignments/mqtt-with-button/mqtt-with-button.pdf
+++ b/assignments/mqtt-with-button/mqtt-with-button.pdf