Count down timer based on PIC16F628A and a watch crystal. Included C code and circuit diagram. Time span is 100 minutes. Setting the time is by MINUTES /
SECONDS pushbuttons which advances the minutes display by 1 per second.
Holding the pushbutton counts faster. Pressing MINUTES and SECONDS
together resets the display. Pressing START / STOP starts the countdown.
Pressing START / STOP during count pauses or restarts the counting. When the time reaches zero the buzzer sounds for
10 seconds and the display flashes.
2 DIGITS LED EGG TIMER
Timer based on PIC16F628A and a watch crystal. Included ASM, C code, and circuit diagram. Time span is 1 to 99 minutes. Setting the time is by +MINUTE/RESET pushbutton which advances the minutes display by 1 per second, the +MINUTE X 10 pushbutton advances the tens of minutes digit. Pressing START sounds the buzzer for 0.25 sec and starts the countdown. When the time reaches zero the buzzer sounds for 20 seconds and the display flashes 'AL'. Pressing +MINUTE/RESET pushbutton resets the timer and/or stops the buzzer.
You are free to use the circuit diagram and the software with no
limitations.
Transistors are BC337 or equivalent. The oscillator
is a watch crystal of 32.768 KHz. The 22pF can vary with different
crystal makes.
The 4 digits display is common cathode, the 7 resistors of 220 ohms enable current of
16 mA max averages at 4 mA through each segment which is on for quarter time. The seven segments, a to g, of one digit are linked to the corresponding seven segments in the other digits.
The decimal point can be used between minutes and seconds. Alternatively
you can use different colour or smaller size digits for the seconds
display.
The buzzer, piezo buzzer is driven by a frequency of
2KHz.
Transistors are BC337 or equivalent.
The 2 digits display is common cathode, the 7 resistors of 390 ohms enable current of 6 mA total averages at 3 mA through each segment which is on for half the time. The seven segments, a to g, of one digit are linked to the corresponding seven segments in the other digit.
The 2 digits are multiplexed by pins 17 and 18 that drive the common cathodes.
The buzzer is driven by a frequency of 1KHz, a piezo buzzer for that frequency will give optimal output.
PCB for 2 Digits Timer by GAB GOB
Gabriel designed a PCB for this project using EAGLE PCB 5.9 .
05.02.2018 - 19:18 Name: Moty Comment: Hi Imsa, You probably need an alarm clock, there are many projects on the net, look at this one: https://github.com/srashid3/embedded-alarm-clock
05.02.2018 - 07:01 Name: Imsa Naga Comment: Dear Sir,
I trying to learn PIC and found your circuit very encouraging.
Would you be kind enough to modify your circuit such that:
1. The timer continues for at least 30 days.
2. Timer Switch ON Buzzer/Relay for 10-15 seconds and switch off and this cycle repeat for the 30 days duration.
3. Provide Re-set Switch
4. Provide Temp&Humidity Sensor with LCD Display
If the above can be shared with all your esteemed readers I am sure there would be may useful applications for the same.
Thank you very much in advance.
imsayuba@gmail.com
30.08.2016 - 08:09 Name: tarek Comment: Bien
11.04.2016 - 06:11 Name: mat Comment: this circuit works?
08.01.2016 - 00:43 Name: JESUS SANCHEZ V Comment: ME PARESEN MUY INTERESANTES TUS DISEŅOS Y PROYECTOS QUIERO PROBAR ESTE TAIMER GRACIAS.
26.12.2015 - 20:02 Name: Moty Comment: Thank you.
I don't use simulators.
26.12.2015 - 13:40 Name: Naser Comment: Hi Dear,
Nice work! Can I have the Proteus project as well please?
Keep up the good work and god bless you.
Naser
28.03.2015 - 16:57 Name: Moty Comment: Hi Sumit, this project doesn't have an output for relay.
27.03.2015 - 18:29 Name: sumit kumar Comment: sir,where add the relay in this circuit...??????
23.01.2015 - 16:30 Name: QAMAR SHAIKH
Comment: LOOKS VERY NICE PROJECT I WILL TRY IT
THANKS
REGARDS.
28.11.2014 - 04:17 Name: Jack Schmidling Comment: Everything works but the countdown. I can set the mins and 10mins but all it does is blink when I press start. The beeper blinks also but that is the end of the joy.
Any ideas what I am doing wrong?
Jack
Marengo, Illinois
27.11.2014 - 20:37 Name: Moty Comment: Hi Jack,
I've never tested the HEX file generated by MPLAB X so that could be a source of problems. Try programming the pic with the HEX file in the MPLAB or ASM folder.
If any of the LED digits goes off after pressing Start then it could be the crystal oscillator, try changing the 2 caps of 47pF to 22pF.
Check that your 5V supply doesn't dip below 4.5V when you press Start, the brown-out reset operates at 4.5V.
27.11.2014 - 04:55 Name: Jack Schmidling Comment: Everything works but the countdown. I can set the mins and 10mins but all it does is blink when I press start. The beeper blinks also but that is the end of the joy.
Any ideas what I am doing wrong?
Jack
Marengo, Illinois
21.08.2014 - 12:55 Name: Moty Comment: Hi Guptab.
Yes, you can use this project in your commercial circuit. You are free to use the circuit diagram and the software with no limitations.
I'll be happy to look at your final product when you have info for it.
20.08.2014 - 19:59 Name: guptab Comment: Can i use it in my commercial circuit
26.04.2014 - 17:56 Name: jayendra Comment: we want memory back up
24.04.2014 - 00:25 Name: manoj soorya Comment: I get this error while compile
Build C:\Documents and Settings\sethu\Desktop\egg_timer\New Folder\t for device 16F628
Using driver C:\Program Files\HI-TECH Software\PICC\std\9.60\bin\picc.exe
Executing: "C:\Program Files\HI-TECH Software\PICC\std\9.60\bin\picc.exe" -q -g --asmlist --chip=16F628 "--errformat=Error [%n] %f; %l.%c %s" "--msgformat=Advisory[%n] %s" "--warnformat=Warning [%n] %f; %l.%c %s" -P --char=unsigned -C "C:\Documents and Settings\sethu\Desktop\egg_timer\egg_timer.c"
Warning [176] C:\Documents and Settings\sethu\Desktop\egg_timer\egg_timer.c; 144.0 missing newline
Error [987] C:\Documents and Settings\sethu\Desktop\egg_timer\egg_timer.c; 30.16 arguments redeclared
Warning [361] C:\Documents and Settings\sethu\Desktop\egg_timer\egg_timer.c; 107.1 function declared implicit int
Warning [361] C:\Documents and Settings\sethu\Desktop\egg_timer\egg_timer.c; 119.1 function declared implicit int
Warning [337] C:\Documents and Settings\sethu\Desktop\egg_timer\egg_timer.c; 143.15 line does not have a newline on the end
********** Build failed! **************
24.04.2014 - 00:07 Name: manoj soorya Comment: Hi moty,
Can you give me the hex file for what i Want? Its a request...I cant compile with Hi-Tech compiler...I dont know why?...
23.04.2014 - 23:56 Name: manoj soorya Comment: Hi moty,
Can you give me the hex file for what i Want? Its a request...I cant compile with Hi-Tech compiler...I dont know why?...
23.04.2014 - 22:31 Name: Moty
Comment: Hi Manoj, For the C code I use the free Hi-Tech compiler that comes with the MPLAB. To use another compiler you need to migrate the code.
It is quite easy to change the code to a power off timer and I'm sure you will enjoy doing it.
23.04.2014 - 18:26 Name: Manoj Soorya Comment: Which compailore you used?
22.04.2014 - 23:37 Name: manoj soorya Comment: Power Off Timer means when press the start button, the 13th pin of 16F628 was ON. When the time reaches 00, the 13th pin OFF. Please provide me the code and schematic.
Thank you for your GREAT PROJECT.
22.04.2014 - 23:32 Name: Manoj Soorya Comment: Hi Motty...
Can you make a power off timer as same as the above timer...Its super for me.
Thank you for sharing.
21.04.2014 - 20:55 Name: edo Comment: super projekt,thank you!
21.04.2014 - 20:21 Name: edo Comment: super projekt,thank you!
14.04.2014 - 16:36 Name: jayendra Comment: We want memory in this timer
16.09.2013 - 02:21 Name: Moty Comment: Hi Ray.
I don't have a basic code for the projects. Try Google or MikroElectronica for a converter.
15.09.2013 - 01:36 Name: Ray Comment: Could you email me a copy in basic.?? I don't know asm or hex programing or do you know of a program that will convert hex or asm to basic??? I would like to change the time from 99 minutes to ten and remove all start buttons works on power up in other words a 10 minute timer Thanks for any comments Ray
11.09.2013 - 15:59 Name: spirou Comment: very nice, thank you for the sharing
I completed the installation and it works perfectly,
I will wish to make just one change on the asm program for the start button or a switch, the countdown time is running when the contact is closed (and remains closed); if the contact opens the timer is stopped
Thank you very much in advance for all
10.09.2013 - 23:04 Name: michel Comment: very nice project thank you
10.09.2013 - 23:03 Name: Comment:
11.04.2013 - 13:50 Name: Moty Comment: Hi Gabriel.
Thank you for the offer. If you wish I can add the PCB to the website with credit to your name. My egg timer is built on a stripboard, your PCB can be helpful to others.
11.04.2013 - 01:29 Name: Gabriel Comment: Hi Dear,
I'm starting with this project, as I can do to count 99 seconds? if you want I can send the eagle PCB for this project. Very good job, thank you!
03.11.2011 - 14:55 Name: John Comment: Thanks for this fine project.
If you need a PCB board for your next project, I can recomend
www.h-instruments.ecrater.com. 5 pcs 50x50mm 2 layer for 29.95$ 26.05.2010 - 23:43 Name: Comment:
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