Hardware quick-fire questions
How do I upload code to the Arduino Yun?
You can use a USB cable, but it needs the USB A connector (the large flat one) at both ends because the Yun doesn’t have a USB B socket. Much simpler is to use Wi-Fi. Once the Yun is connected to your network, select Tools > Board > Arduino Yun in the Arduino editor. The app will locate the network address to use but this can take a few minutes because the Wi-Fi connection on the Yun is handled by a separate processor running Linux and it is slow to boot up.
Does Blynk cost money to use?
No. Each widget uses in-app currency when you first add it to your UI but you begin with enough free currency for a simple app. Actually running Blynk doesn’t cost anything.