12Hrs LED clock ( Almost No Parts Very accurate timing )

[pasanlaksiri]

12Hrs LED clock ( Almost No Parts Very accurate timing   )

The processor that I am using here is PIC16F628A. Im testing this clock for months now still no error.  There are no resistors for displays because
I limit the current using the software instead of using resistors.

More info about Zero-error 1 second Timer >> http://www.romanblack.com/one_sec.htm







PCB Arts

   

Silk Screen Layouts

Controle Board BOTTOM
http://www.4shared.com/file/236695715/97e5185a/Controle_Board_BOTTOM.htmlControle_Board_BOTTOM.html
Controle_Board_TOP
http://www.4shared.com/file/236695744/9d95dc89/Controle_Board_TOP.html
SSD_Board_BOTTOM
http://www.4shared.com/file/236695925/b6566693/SSD_Board_BOTTOM.html
SSD_Board_TOP
http://www.4shared.com/file/236696025/ab32f2f2/SSD_Board_TOP.html

Firmware

http://www.4shared.com/file/236699902/50d22e0a/Firmware.html

Please use mikroC Pro demo to open the files.

Download mikroC Pro Demo
http://www.mikroe.com/zip/mikroc_pic_pro/mikroc_pro_pic_2009_v320_setup.zip


http://pasanmicroprojects.wordpress.com

[bbarney]

pasanlaksiri
You posting just pictures of your projects with no code or schematics is not sharing with the community but just patting yourself on the back saying nice job
You are not going to turn this site into another of your Blog's
Either post the entire project or delete this post and others like it and just keep it on your Blog

[solutions]

I got curious about this Bresenham name-dropping (with no link) as, being an engineer, I don't have a lot of tolerance for academic elitists.

Those of you wondering how pasanlaksiri did it, the source code and "schematics" for a super accurate PIC-based one second clock tick is here  http://www.romanblack.com/one_sec.htm and shows the calibration techniques.

Posted on: March 08, 2010, 04:46:53 04:46 - Automerged
The no resistor LED drive from a PIC trick is on the same website  http://www.romanblack.com/led_none.htm

cheers,

-S

[FriskyFerret]

Did anyone notice Roman Black mentions that he is controlling current with a LED PWM scheme?

The schematic is simple; the 8 segments (includes decimal point) connect direct to 8 PIC pins on PORTB, the 12 digit cathodes connect to 12 PIC pins on PORTA and PORTC. As you can see below the PIC just connects directly to the 20 pin connector on the LED display. It uses SOFTWARE to provide a low duty cycle and control the LED current for each segment.

He's controlling the average power to the LED with direct PWM. Generally, average power is the limiting factor to driving common LEDs. Peak pulse current current may be very high as in the case of pulsed IR used in remote controls.

[solutions]

Yes - I was scratching my head a bit on what Roman was doing - he's relying on the channel saturation of the output stage of the PIC buffers to keep from smoking everything - it is clever (as are many of the things on his website), though the buffer's channels will still get awfully hot at the scale of the transistor with the pulsed power, irrespective of the average temperature of the silicon die.  See Power MOSFET data sheets for the analogy.

I can't help but wonder whether his clock, or the one pictured in this thread, will make it past two years. You'll notice they never put digits on it for day and year....