Let the Arduino sketch create a GUI with Graphics, Buttons and Sliders on your smartphone by simply connecting a HC-05 to the rx/tx pins of your Arduino. Directly connecting the Arduino with an USB cable and an USB-OTG adapter to your smartphone is also supported.
It receives draw requests from Arduino over Bluetooth and renders it. GUI callback, touch and sensor events are sent back to Arduino. No Android programming needed!

• Touch button + slider objects with tone feedback.
• Button and slider callback as well as touch and sensor events are sent back to Arduino.
• Graphic + text output as well as basic printf implementation.
• Draw chart from byte or short values. Enables clearing of last drawn chart.
• Play system tones.
• Automatic and manually scaling of display region.
• Easy mapping of any UTF-8 characters like Ohm, Celsius etc..
• Up to 115200 Baud using HC-05 modules or OTG cable.
• USB OTG connection can be used instead of Bluetooth.
• Local display of received and sent command log for debugging purposes.
• Hex and ASCII output of received Bluetooth data at log level verbose.
• Debug messages shown as toasts.
• Swipe from the left border opens the options menu.
• C++ Libraries for Arduino. and ARM (STM).

You can load the library with Tools -> Manage Libraries... or Ctrl+Shift+I. Use "BlueDisplay" as filter string. The library includes examples for easy initializing a HC-05 and for a simple DSO with 0.3 megasamples/sec.

Before using the examples, take care that the BT-module (e.g. the the HC-05 module) is connected to your Android device and is visible in the Bluetooth Settings. For full screen applications, the menu is called by swiping from the left edge of the screen. Otherwise, you can call it by touching the area not occupied by the client application (black display area).

All examples initially use the baudrate of 9600. Especially the SimpleTouchScreenDSO example will run smoother with a baudrate of 115200. For this, change the example baudrate by deactivating the line #define HC_05_BAUD_RATE BAUD_9600 and activating #define HC_05_BAUD_RATE BAUD_115200. AND change the BT-Module baudrate e.g. by using the BTModuleProgrammer.ino example.

Android axis are defined for natural screen orientation, which is portrait for my devices:

• When the device lies flat on a table and its left side is down and right side is up or pushed on its left side toward the right, the X acceleration value is positive.
• When the device lies flat on a table and its bottom side is down and top side is up or pushed on its bottom side toward the top, the Y acceleration value is positive.
• When the device lies flat on a table, the acceleration value along Z is +9.81 (m/s^2).

The BlueDisplay application converts the axis, so that this definition holds for each screen orientation.

V Hex= 00 4C 13 A5 01 08 00 53 65 74 74 69 6E 67 73 A5
V Asc=     L                 S  e  t  t  i  n  g  s
V Hex= 70 12 00 04 00 00 00 00 00 60 00 34 00 00 F8 0B
V Asc=  p                          `     4
V Hex= 03 00 00 30 21 A5 01 07 00 48 69 73 74 6F 72 79
V Asc=           0  !              H  i  s  t  o  r  y

If you need debugging with print() you must use the debug() functions since using Serial.print() etc. gives errors (we have only one serial port on the Arduino) . E.g.

BlueDisplay1.debug("\r\nDoBlink=", (uint8_t) doBlink);

To enable programming of the Arduino while the HC-05 module is connected, use a diode to connect Arduino rx and HC-05 tx. On Arduino MEGA 2560 TX1 is used, so no diode is needed.

                 |\ |
   Arduino-rx ___| \|___ HC-05-tx
                 | /|
                 |/ |

BlueDisplay example breadboard picture Fritzing schematic for BlueDisplay example DSO with passive attenuator on breadboard At work Fritzing Schematic DSO settings menu DSO frequency generator menu Hacked RC car

RC car control display

• Targeted Android 13 / 33

• Targeted Android 12 / 32
• Support for new function disableAutorepeatUntilEndOfTouch().
• Added Flag FLAG_SLIDER_VALUE_CAPTION_TAKE_DEFAULT_MARGIN. Margin is set to RequestedCanvasHeight / 60.
• Inproved color handling for red / green button.

• Fixed Permission bug for Andoid 12 / 32

• New command FUNCTION_CLEAR_DISPLAY_OPTIONAL to enable resynchronization of slow displays.
• Bluetooth random delay detection.
• Fixed bug for micro-swipe suppressing.
• Added Slider command SUBFUNCTION_SLIDER_SET_DEFAULT_COLOR_THRESHOLD.
• Opening options menu by swipe now not restricted on full screen and connected.
• Strings printed with Serial.print() are not interpreted, but stored in the log for debug purposes.
• Fixed bug in FUNCTION_BUTTON_REMOVE.
• Fixed bug in SUBFUNCTION_SLIDER_SET_POSITION.

• Swipe from the left border in application full screen mode opens the options menu.
• Removed unnecessary message on no data received under certain circumstances.
• Added parameter values *LOCK_SENSOR_LANDSCAPE and *LOCK_SENSOR_PORTRAIT for function setScreenOrientationLock().
• Slider caption handling improved.
• Added short drawText functions.

• Improved startup. New message if no data received after connect and part of screen is inactive/black, to access the options menu.

• Connection with USB OTG cable now also possible. In this case no Bluetooth adapter is needed.
• Handling of no input for getNumber.
• Slider setScaleFactor() does not scale the current value, which is delivered as initial value at init().
• Improved tone volume setting - can be adjusted at the smartphone too. trim() for all button caption strings.

• connect, reconnect and autoconnect improved/added. Improved debug() command. Simplified Red/Green button handling.

• Slider scaling changed and unit value added.

• Timeout for data messages. Get number initial value fixed.
• Bug autorepeat button in conjunction with UseUpEventForButtons fixed.

• Fixed silent tone bug for Lollipop and other bugs.Multiline text /r /n handling.
• Android time accessible on Arduino. Debug messages as toasts. Changed create button.
• Slider values scalable. GUI multi touch. Hex and ASCII output of received Bluetooth data at log level verbose.

• Improved tone and fullscreen handling. Internal refactoring. Bugfixes and minor improvements.

• Local display of received and sent commands for debug purposes.

• Android sensor accessible by Arduino.

The USB driver library used in this project is Kai Morichs fork of usb-serial-for-android