Instructions for use and setting of the Digital Alarm Clock

Introduction

The clock is assembled using components purchased from Adafruit and other commonly available sources.

It uses either an Adafruit Feather M0 Express or an Adafruit M4 Express,

(NB. The two processors use different Audio Libraries I recommend the Adafruit Feather M4 Express as it has an Adafruit maintained audio library),

an Adafruit Adalogger Featherwing which includes a Real Time Clock and an SD card reader,

an Adafruit 4-Digit 7-Segment LED Matrix Display FeatherWing (or alternative 14 segment display),

An Adafruit Mono 2.5W Class D Audio Amplifier.

The microprocessor is programmed using the Arduino IDE. The date and time can be set using the buttons provided and, in addition the “Daylight Saving Time” zone (currently Europe or USA) can be set for automatic corrections and the options of 12 or 24 hour display.

The brightness of the display is reduced during night hours either set by specific times, or using a Photo Transistor Light Sensor.

Buttons

Alarm button

The central button on the top of the clock is the Alarm button. This is the only button which latches down and is released when pressed.

When the Alarm button is down the Alarm is turned off and the “+” and “-” buttons on the rear of the clock can be used to adjust the time. The LED light in the button is off.

When the Alarm button is released the button light is switched on and the display indicates the current alarm time for several seconds (the default is 8:30 AM). Depending on the display used a dot in the lower right of the display may be turned on as an additional indication that the alarm is active. When the Alarm button is in the up position the “+” and “-” buttons on the rear of the clock can be used to adjust the Alarm time.

When the Alarm sounds (music or tone stored on the SD card) pressing the Alarm button to the down position turns the Alarm off and returns the rear buttons to time setting mode.

Optional Talk the Time button.

The clock may optionally be fitted with a button that can be used to vocally speak the time using prerecorded numbers and phrases. This is useful for people with impaired vision. In this case the button is always lit and pressing the button for one second will trigger a vocal announcement of the time. If the Talk the Time button is fitted the Alarm button may be optional.

“+” and “-” buttons

The “+” and “-” buttons are situated to the left and right on the rear of the clock.

When the Alarm button is depressed the buttons are in time setting mode. The buttons will increase or decrease the time by minutes. After being held down for several seconds the speed of change will increase. Note that passing midnight will also change the date!

When the buttons are released the minute is set to with zero seconds. Hint: for accurate time setting the clock time can intentionally be set a minute above or below the actual time then, on the exact change of minute ether the “+” or “-” button can be momentarily pressed to set the exact time. This may require a couple of attempts to get right. Alternatively a single click on the OK button will zero the seconds of the currently displayed minute.

When the Alarm button is released (in the up position and with the light on) the setting buttons are in Alarm setting mode. The “+” and “-” buttons will increase or decrease the Alarm time by minutes. After being held down for several seconds the speed of change will increase. The Alarm time can only be set for a particular hour and minute.

Note that passing midnight will NOT change the date!

“OK” button

The “OK” button is mainly used to set the clock parameters, “Daylight Saving Time” zone (currently Europe or USA), 12 or 24 hour display and, if necessary, the date. It can also be used, if necessary as a reset.

Double click: a double click of the “OK” button will restart the clock program. This will normally not affect stored parameters or the time and date. In the case that parameters or time is obviously incorrect the parameters, date, and time may need to be reset.

Hint: the fastest way to reset the alarm time is with a double click on the “OK” button.

Long press: a long press of the “OK” button for more than 2 seconds will cause the clock to enter the “Parameter” and date setting mode. Note that if no button is pressed for one minute the clock will exit back to its normal function.

Single click: a single click of the “OK” button accepts the parameter or date and moves on to the next function.

When in normal time display mode a single click of the “OK” button synchronises the clock to a known time source by adjusting the seconds up to the next minute if the clock is less than 30 seconds slow or, if the clock is up to 30 seconds fast it will reduce the seconds to the current minute.

Hint: for accurate time setting set the clock to the time displayed on the reference device as closely as possible and then, when the time displayed on the reference device changes, a single click of the “OK” button will zero the seconds to match the reference device time. This is easiest if the reference device shows the time with seconds.

Setting the Parameters and Date

After a long press (3 seconds) on the Ok button the display will flash “DST” and then show the current “Daylight Saving Time” zone. Using the + or – button will change the zone, currently No, US, or EU.

If the zone is correct click the OK button.

The display will flash 24hr – 12hr followed by the current display mode. Using the + or – button will change the display mode between 24hr and 12hr.

When the correct display mode is selected click the OK button.

The display will then flash “YYYY” followed by the current year. Using the + or – button will increase or decrease the year.

If the year is correct click the OK button.

The display will then flash “MM:DD” with only “MM” flashing. (Note: “nn” on the 7 segment display because the letter “M” can not be displayed). The current month and day will then be displayed. Using the + or – button will increase or decrease the month.

If the month is correct click the OK button.

The display will then flash “ DD”. The current month and day will then be displayed. Using the + or – button will increase or decrease the day.

Note: passing over the end or beginning of the month will change the month.

If the month and day is correct click the OK button.

The clock will then return to normal timekeeping mode and the hour and minute can be adjusted (always provided that the Alarm button, if it exists, is depressed). When in normal time display mode a single click of the “OK” button synchronises the clock to a known time source by adjusting the seconds up to the next minute if the clock is less than 30 seconds slow or, if the clock is up to 30 seconds fast it will reduce the seconds to the current minute.

Updated: 30 January 2024