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Demonstration of Talkie voltmeter example	Intoduction by Gadget Reboot

Improvements to the original and to the non blocking version of PaulStoffregen

• Improved code so Talkie now runs on 8 MHz Arduino (with millis() interrupt disabled while talking).
• Fixed the ISR_RATIO Bug for plain Arduino.
• Added utility functions sayQNumber(), sayQFloat(), sayQVoltageMilliVolts() extracted from the examples.
• Inverted output at pin 11 is enabled by default to increase volume for direct attached piezo or speaker.
• Added comments and did refactoring to better understand the functionality.
• Added compatibility to Arduino Tone library by stopping timer1 interrupts at every end of speech.
• Extracted initializeHardware() and terminateHardware() functions for easy adapting to other platforms.
• Currently supporting:
  • ATmega328 as found on the Uno and Nano boards.
  • ATmega2560 as found on the MEGA 2560 board.
  • ATmega32U4 as found on the Leonardo and CircuitPlaygound boards.
  • ARM M0 (Tested for Arduino Zero) as found on the SAMD, Teensy and Particle boards.
  • ESP32. ESP8266 is theoretical possible using FRC2, but for now Arduino shares the FRC1 timer between interrupts and PWM.
  • ARM M3 (Tested for BluePill) for Roger Clarks as well as STM core.

Pin and timer mapping table for different platforms

Timer usage

Timer 1 (Servo timer) is used at all ATmegas for updating voice output data at 8 kHz.
Timer 2 (Tone timer) on ATmega328 (62500 Hz / 16 µs) or Timer 4 on ATmega2560 + ATmega32U4 (5 µs) is used to generate the 8 bit PWM output.
Both timers are therefore not available for other libraries / purposes, like servo control or tone output.

Differences between BluePill cores

There are two cores for the BluePill.

• The STM32F1 by Roger Clark; http://dan.drown.org/stm32duino/package_STM32duino_index.json
• The CMSIS based stm32 by ST Microsystems; https://github.com/stm32duino/BoardManagerFiles/raw/master/STM32/package_stm_index.json

Generation of the high speed PWM is complicated for Roger Clark core and easy for the STM core. Program size for VoltmeterSayQ.cpp is 21 kByte for Roger Clark core and 32 kByte for STM core. The 8 kHz interrupt handling requires 8 µs for Roger Clark core and 12 µs for STM core.

Hints

• As default both inverted and not inverted outputs are enabled to increase volume if speaker is attached between them.
• The library uses Timer 1 and Timer 2 on ATmega328, so libraries like Tone, Servo, analogWrite(), and some other libraries cannot be used while speaking.
• After a call to say...() you can use tone() again.
• using [Sloeber]ervo write() after a call to say... you must detach() and attach() the servo before first write() in order to initialize the timer again for Servo.
• If you want to use SPI functions on ATmega328 while Talkie is speaking, then disable Talkies usage of pin 11 by Talkie Voice(true, false); instead of Talkie Voice; or Voice.doNotUseInvertedOutput();.
• Porting to ATtinys is not possible, since they lack the hardware multiplication. ( Believe me, I tried it! )
• I use the speakers from old earphones or headphones, which have approximately 16 to 32 Ω, directly without a series resistor on my ATmegas. The headphone speaker tend to be much louder, especially when they stay in their original housings. If you do not connect the speaker between non inverted and inverted output, you must use a series capacitor of 1 to 10 uF do block the DC current. Look for the right polarity. The AC current is proportional to the rectance of the speaker, not its resistance in Ω, and it is between 10 and 40 mA. The latter is definitely out of specification for ATmegas but quite loud -what you hear is what you supply- and running for hours on my desk. If you are not sure, just use a piezo speaker or a power amplifier.

Predefined vocabulary

The predefined vocabulary can be found in the Vocab_*.h files, especially in Vocab_US_Large.h.

Own vocabulary

To create LPC data you can use the python_wizard like described here or the BlueWizard for Mac OS X.

Another way to create LPC data is to use Qboxpro, an unsupported old Windows application running under XP, which can produce Talkie compatible data streams. The missing BWCC.DLL (Borland Windows Custom Control Library) can be found e.g. here. The process is described here and goes like this:

• Create a new project using the following project parameters : byte / 8 KHz / 5220 coding table
• Goto Project and add the audio file
• Choose process using : medium bit rate and pressing OK
• Edit concatenation : insert concatenation after by adding a name; then insert phrase and press OK
• Format it by choosing the first line in the format menu : LPC 10V, 4UV

OUTPUT FILTER

    C to avoid clicks  Low pass 1600Hz  DC decoupling (optional)
                      _____
  D3 >------||-------| 10k |---+----------||-------> to Power amplifier
           100nF      -----    |         10nF
                              ---
                              --- 10 nF
                               |
                               |
                               _ GND

Compile options / macros for this library

To customize the software to different requirements, there are some compile options / macros available.
Modify them by enabling / disabling them, or change the values if applicable.

Changing include (*.h) files with Arduino IDE

First, use Sketch > Show Sketch Folder (Ctrl+K).
If you have not yet saved the example as your own sketch, then you are instantly in the right library folder.
Otherwise you have to navigate to the parallel libraries folder and select the library you want to access.
In both cases the library source and include files are located in the libraries src directory.
The modification must be renewed for each new library version!

Modifying compile options / macros with PlatformIO

If you are using PlatformIO, you can define the macros in the platformio.ini file with build_flags = -D MACRO_NAME or build_flags = -D MACRO_NAME=macroValue.

Modifying compile options / macros with Sloeber IDE

If you are using Sloeber as your IDE, you can easily define global symbols with Properties > Arduino > CompileOptions.

Schematic for voltmeter example

Revision History

Version 1.3.2

• Fixed ESP32 timer bug.

Version 1.3.1

• Updated _1_Voltmeter example and renamed example names.
• Improved SAMD support.

Version 1.3.0

• Removed blocking wait for ATmega32U4 Serial in examples.
• 10 bit Coefficients are working now, but they do not sound better 😞.
• Tested on an ESP32.
• Tested on a BluePill.

Version 1.2.0

• Corrected wrong function name doNotUseUseInvertedOutput().
• Added functions digitalWriteNonInvertedOutput() and digitalWriteInvertedOutput().

Version 1.1.0

• SAMD support.
• ESP32 support.
• Teensy support.
• Version number.
• Renamed *.c to *.cpp files.
• Added function sayQTimeout() in TalkieUtils.cpp.
• Added example USDistanceToVoice.
• Added function sayQVoltageVolts().
• Improved end handling to minimize clicks.

Version 1.0.2

• ATmega2560 supported and tested
• Always set pins to input when finishing, to avoid a click.

Version 1.0.1

• Added SPI compatibility by not resetting pin 11 to input if SPI is detected
• Added new constructor Talkie(bool aUseNonInvertedOutputPin, bool aUseInvertedOutputPin);

Version 1.0.0

• Initial Arduino library version

CI

The library examples are tested with GitHub Actions for the following boards:

• arduino:avr:uno
• arduino:avr:leonardo
• arduino:avr:mega
• arduino:sam:arduino_due_x
• esp8266:esp8266:huzzah:eesz=4M3M,xtal=80
• esp32:esp32:featheresp32:FlashFreq=80
• STMicroelectronics:stm32:GenF1:pnum=BLUEPILL_F103C8

Requests for modifications / extensions

Please write me a PM including your motivation/problem if you need a modification or an extension.

If you find this library useful, please give it a star.