Really useful information! Get yourself a cup of tea and spend ten minutes reading!GUI Layout Images Cannot Build or Install APK Project File Care Getting Help on the App Inventor Forum Android Versions Extensions For App Inventor Extensions Installation Guide How to Update-Replace an Extension General: App Inventor Learning App Inventor App Inventor For Teachers External Storage Video Arduino, other Microcontrollers & Related Subjects inc Wireless Technologies
My Golden Rules:
Note that if deploying image buttons, especially for toolbars, they may have to be defined in pixels (height and width) to minimise distortion. In my experience, square buttons 50pix x 50pix (min 44pix x 44pix) can serve a range of different phone sizes. A Horizontal Scroll Arrangement (aka container) can ensure the User has access to all of the buttons on the toolbar.Simple GUI 'How To' Movie
Defined and or managed incorrectly, images will take up too much memory and could cause a crash:
Things to look out for:
"Good Housekeeping" pays dividends!
An average of 400,000 Users per month means that you have a lot of competition for the attention of the Power Users (Technical Support Volunteers). Therefore, it is in your best interests to ensure that your help request is very carefully described and where appropriate supported with images and a small Test Project File (.aia) that demonstrates the problem.
If you are communicating with (IOT) hardware such as Arduino, BBC Microbit, Raspberry Pi, Banana Pi -include your Sketch/Script and connectivity (BlueTooth, BlueTooth LE [BLE], Network, WiFi, USB). Include your schematic or circuit diagram too.
If you are having trouble with App Inventor (rather than your work on your App) try this first: MIT: Troubleshooting for App Inventor 2
Description: Tell Us:
How to insert an image of your Blocks into your Forum Post:
How to attach a Project File (.aia) to your Forum Post:
|Name||Version No||API version||Release Date|
|Ice Cream Sandwich||4.0, 4.0.4||14~15||18-10-2011|
|Jelly Bean||4.1, 4.3.1||16~18||09-07-2012|
Learning App InventorMIT Beginner Videos
Hot Tip: Ardunio Sketch (Script): Use println() to separate messages when you transmit.
App Inventor: Set DelimiterByte to 10 in BlueTooth Block.
Check that: Bytes Available > 0 in BlueTooth Block.
Then request -1 bytes to get full message.
Specification of an AC To DC Power Adaptor For Arduino: 9v to 12V max DC output, 250mA to 1A max current output, 2.1mm diameter plug which is centre pin positive.
If you are connecting kit like lots of LEDs, LCDs, servo motors etc, the Adapter should supply at least 500mA, upto 1A max.
Arduino Uno R3 Hole Dimensions mm
Atmel ATtiny85/ATtiny84 (Atmel is part of Microchip Tech) BackOfficial ATtiny85 Website
ESP8266 WiFi Module Back
Hot Tip: The ESP8266 ESP-01 WiFi Module can be used with or without a companion microcontroller. It is an SOC - System On a Chip.ESP8266 Community Forum
LinkIt BackMIT: IoT: Introduction: LinkIt
micro:bit BackMIT: App Inventor Extension for micro:bit
Nordic Thingy 52 BackNordic Semiconductor: Nordic Thingy 52 home page
STM32 32bit microcontroller (ARM Cortex) BackSolderer TV: Communication Between The STM32 And Android Via Bluetooth (HC-06)
PIC micrcontrollers BackDesignSpark: Basics of PIC16F877A microcontroller
8051 8-bit microcontroller (Intel MCS-51) [Embedded Systems] BackNPTEL: PDF: Specifications: Intel 8051 microcontroller
App Inventor BLE requires your device (e.g. SmartPhone) to have Android v5.0 or higher to avoid known issues with Google's Bluetooth LE support prior to Android 5.0.
Some Smartphones will not work with BLE unless Google Location is activated. Particularly so with Alcatel devices.
Hot Tip for BLE: Some of the BLE modules arrive with very little information (or none at all). To communicate with them, you need their UUIDs. Bluepixel Technology have written a Scanner App to help verify UUIDs. Down load it from the Google Play Store: BLE ScannerJon Gunnar Sponås: Effective Range of Bluetooth Communications
|Text String Character Sets Supported by App Inventor Bluetooth Classic|
|US-ASCII||Seven-bit ASCII (ISO646-US), the basic Latin block of the Unicode character set. 127 characters|
|ISO-8859-1||ISO Latin Alphabet Nº1, (ISO-LATIN-1)|
|UTF-8||Eight-bit UCS Transformation Format|
|UTF-16BE||Sixteen-bit UCS Transformation Format, big-endian byte order|
|UTF-16LE||Sixteen-bit UCS Transformation Format, little-endian byte order|
|UTF-16||Sixteen-bit UCS Transformation Format, byte order identified by an optional byte-order mark|
|BR:||Basic Data Rate max 1Mbps|
|EDR:||Enhanced Data Rate max 3MBps|
|HS:||High Speed Data Rate max 24Mbps|
|SAM:||Slot Availability Masking - detect and prevent interference on neighbouring radio bands|
|Classic:||Higher power consumption, less advanced comms. *version 3.x consumes more power than v2.x|
|BLE:||Bluetooth Low Energy (for battery powered devices), advanced comms with GATT Generic Attributes hierarchical data structure|
Wireless Technologies Back
Including Bluetooth, there are many other wireless technologies to choose from!John Teel: Comparison of Wireless Technologies Bluetooth Classic, WiFi, BLE, Zigbee, Z-Wave, 6LoWPAN, NFC, WiFi Direct, GSM, LTE, LoRa, NB-IoT, and LTE-M
App Inventor Extensions
Extensions Library maintained by App Inventor Expert Taifun Baer, including his own excellent ProductsPura Vida: App Extensions
ClientSocket (TCP) Extension by Jean-Rodolphe Letertre. An extension to send/receive data directly, App to/from WiFi Device (ESP8266)
How to install an Extension in App Inventor
Example Extension: MIT Bluetooth Lite Edition (BLE) Extension
How to Update or Replace an Extension without losing the associated Blocks
I use the BLE extension as an example. The process is the same for any Extension being updated or replaced.
Follow the following Steps, in the order listed:
Blocks Work Area
Designer Work Area
Blocks Work Area