Summary of Tag Archives: arduino speaking clock
This article details the construction of a Speaking Clock using an Arduino Mega 2560 and a Wave Shield. It explains pin remapping for DACs, configuring the LCD in 4-bit mode, and using a hex Schmitt inverter (U2) for button debouncing. Audio is generated by recording tracks in Audacity as mono WAV files (16-bit PCM, 22 KHz), which are stored on a FAT-formatted SD card. The system reads these files to play time announcements in English or Yoruba.
Parts used in the Speaking Clock:
- Arduino Mega 2560
- Wave Shield
- SD/MMC Card
- LCD Display
- Hex Schmitt Inverter IC (U2)
- Speaker
- Resistors and Capacitors for RC circuit
- Audacity Software
How to: Speaking Clock
Hello 🙂
Setup and Procedure
The wave shield is interfaced with the Arduino Mega 2560 as normal. A couple of pins were remapped because the wave shield was initially made for a different device. The DAC pins were remapped to pins 22,23,24 and 25 on the Arduino board. The WaveHC library also has to be modified to accommodate these changes. It is self-explanatory. The SD card communications pins MISO (Master-in-slave-out), MOSI (Master-out-slave-in), CS (chip select) and SCK (clock) are unchangeable and specific for every microcontroller used. For this project, they are pins 50,51,52 and 53. Refer to the pin mapping diagram for details.
Only four data pins were connected from the LCD to the Arduino. This is the 4-bit data transfer mode. The 4-bit mode is efficient for simple alphanumeric data transfer. The RW (Read/Write) pin was grounded because data is only being sent to the LCD and not read from it. RV1 is contrast control for the LCD.
U2 is a hex Schmitt inverter IC used in this case for debouncing the button. The RC time constant = 0.1s which is good enough for the debounce. This could have also been achieved by software easily. Note: In my project, all the buttons were debounced using U2. Software debouncing could have been used as well, I only had a few problems doing that.
The sounds could have been achieved using a voice synthesizer but that incurs some cost. Instead, the sounds were recorded and converted to forms easy to process by the microcontroller.
Each individual audio track was recorded in Audacity and converted to WAV files understandable by the computer. The track properties were set to 16-bit PCM and rate was set to 22 KHz. It is not the best audio quality but the DAC can certainly handle the processing fairly well. The tracks were converted to mono because there is only one speaker. Stereo works but would be ambiguous and pointless.
An easy procedure is to record all the tracks on a single WAV file and export selected WAV’s. Every audio track is saved to the root directory on the SD card with relatively simple files names such as ’01.WAV’ for quick access to the root folder by the microcontroller.
The SD/MMC card must be formatted with the FAT file system before any recording is stored in it. FAT16 and FAT32 file systems are common and compatible with almost every system including cameras and microcontrollers.
*Check the English and Yoruba folders for recordings.
For more detail: Tag Archives: arduino speaking clock
- Which pins were remapped for the DAC?
The DAC pins were remapped to pins 22, 23, 24, and 25 on the Arduino board. - What file system must the SD card be formatted with?
The SD/MMC card must be formatted with the FAT file system, such as FAT16 or FAT32. - How was the LCD connected to the Arduino?
Only four data pins were connected from the LCD to the Arduino using the 4-bit data transfer mode. - Why was the RW pin grounded?
The RW pin was grounded because data is only being sent to the LCD and not read from it. - What component was used for debouncing the buttons?
A hex Schmitt inverter IC labeled U2 was used for debouncing the buttons. - What audio format settings were used for the recordings?
The tracks were recorded as 16-bit PCM at a rate of 22 KHz. - Why were the audio tracks converted to mono?
The tracks were converted to mono because there is only one speaker and stereo would be ambiguous. - Can software debouncing be used instead of hardware?
Yes, software debouncing could have been used, but the author encountered problems doing that. - Where are the audio files saved on the SD card?
Every audio track is saved to the root directory on the SD card with simple filenames like 01.WAV.
