Projects, past & present

The Dawn Clock

This project was embarked upon after buying (at some expense) two different alarm clocks that used a light source to simulate dawn breaking - accompanied by selectable sounds.

Neither worked satisfactorily. I wanted a realistic (and gentle) awakening to the morning sunrise, to be followed by bird, sea or lapping water. Anyhow, the proprietary devices were pretty poor. At best the lamps used reached max brilliance in about four levels and the sounds were predetermined and very artificial.

I wanted an alarm that produced a very gradual increase in light intensity (finally to be about 4,000 steps over a period of 1 to 30mins) and having reached maximum brillians, one of a series (nine were deemed enough) of pre-recorded sounds would play for a chosen duration (ie length depending on record time).

I based the design upon the 16F877, this had the necessary EEPROM and I/O needed. The display was a backlight LCD (standard Hitachi configuration - 2 rows x 16 chars). After much deliberation, I settled for the 'easy' option of using a Real Time Clock (RTC), freeing up processor time for the 'fun' bits!. For the sound generation I selected an MP3 module, as each of these devices were readily available and extremely affordable.

The Dawn Alarm Clock Operation


The clock shows the current time (24hr format) and can be set to simulate the dawn sunrise, after which an alarm sound can be played.


  • The Dawn/Alarm light can be set to have a ‘sunrise’ duration of 1 to 30mins (or OFF).
  • When the Dawn duration expires, any alarm sound track (labelled 1-9) that has been selected will be played (track durations vary).
  • Once the Dawn time and duration settings have been entered and the Alarm has been set to ON, the display will show the current time and the Dawn start time (eg ‘Dawn @ 7:50’).
  • When the Dawn Alarm has been set to OFF, the display will show the current time and the three setting options (ie ‘Hms Dawn Snd’).
  • Once the Dawn time is reached, the light will gradually brighten. When the Dawn light reaches full brightness, the selected sound track will be played. The sound will continue until the sound track ends or until the DOWN (yellow) button is pressed to cancel the sound.
  • If both the UP & DOWN (green & yellow) buttons are pressed simultaneously, the sound and light are turned off, and the Dawn Alarm condition is reset.
  • If the alarm is not cancelled (ie green & yellow buttons not pressed simultaneously) the Dawn Light will extinguish after 20mins.


There are three clock setting options: Set Time; Set Dawn & Set Sound


Pressing the SET TIME (Hms) button will allow the current HOUR, followed by the current MINUTE and finally the current SECONDS to be set. The UP/DOWN buttons allow the current time setting to be increased/decreased. NB The clock uses a 24hr format. A final press of SET TIME will exit the routine.


  • Pressing the SET DAWN (Dawn) button for the first time, allows the Dawn ALARM function to be toggled between ON & OFF using the UP & DOWN buttons.
  • If ‘OFF’ has been selected, the SET DAWN routine will terminate when the SET DAWN button is again pressed.
  • If ‘ON’ has been selected the options continue, allowing the HOUR & MINUTE that DAWN is to begin (ie the lamp will begin to light). The UP/DOWN are used to increase/decrease the DAWN start time.
  • A further press of the SET DAWN button continues ‘Dawn’ duration. This can be set to between 1 and 30 minutes (and OFF). This is the period over which the Dawn light will increase from off to fully illuminated. A final press of the SET DAWN button will exit the routine. NB the Dawn light will be turned off after 20mins.


Pressing the SET SOUND (Snd) button for the first time, allows one of the Dawn alarm sounds to be selected (1 to 9 and OFF). The UP & DOWN buttons cycle through the sound tracks, a sample of each is played when selected. Having chosen a specific alarm sound, pressing the SET SOUND button will continue to the sound volume setting. The UP & DOWN buttons allow a sound level of 1 to 4 (ie 1=quiet; 4 = loud).

A final press of the SET SOUND button will exit the routine.


The display backlight adjusts to the level of the ambient light (NB the sensor is at the back of the unit). However, pressing either of the three SET buttons will increase the backlight to full brightness. At the end of a ‘setting’ operation the backlight will return to the ambient light level setting.

Pressing the UP button (green) turns the backlight to full brightness.

Pressing the DOWN buttons returns the backlight to its ambient light setting.


Pressing the UP & DOWN keys simultaneously will turn both the Dawn Light and alarm sound OFF and cancel the Alarm ON condition.

If the sound track is playing, it can be turned off by pressing the DOWN (yellow) button.

The Dawn Clock has been in daily use for over three years (@ 2014) and has not let us down once, and 'yes' it does exactly what I had hoped. It offers complete control of timing and duration of the Dawn, the wake-up sounds and sound level. what's more, with home-made device, every part is easily replaceable.


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