Very Simple LED Clock Using 16F84A or 16F628A - Electronic Circuits Projects Diagrams Free

pasanrobotics · 13th February 2007, 03:37 PM

Its working perfectly.

Go here for more Details

Gayan Soyza · 14th February 2007, 02:06 AM

Nice fully compact design.All with familliar parts.
PORTA drivng the common of the segments directly???????and the rows also same.It can cause load more current through the PIC pin even when its in multiplexing mode.
Thankx for sharing.....

blueroomelectronics · 14th February 2007, 02:15 AM

It is possible with some fancy programming to light only one segment at a time. It's done here with the super probe.
http://members.cox.net/berniekm/super.html

pasanrobotics · 14th February 2007, 02:23 AM

Quote:

Originally Posted by blueroomelectronics

It is possible with some fancy programming to light only one segment at a time. It's done here with the super probe.
http://members.cox.net/berniekm/super.html

Wow that prob is damn superb. Thanks

bananasiong · 14th February 2007, 10:32 PM

Is there any different of connecting the 7-segment display directly to the output port without any current limiting resistor as compared to drive the 7-segment display with transistor plus current limiting resistor? Since the output current of the PIC's is only 25 mA, it won't burn the LED right?

picasm · 14th February 2007, 11:05 PM

Quote:

Originally Posted by bananasiong

Is there any different of connecting the 7-segment display directly to the output port without any current limiting resistor as compared to drive the 7-segment display with transistor plus current limiting resistor? Since the output current of the PIC's is only 25 mA, it won't burn the LED right?

I do not fully trust the "25mA port limit" that is often referred to in various data sheet documents.
I think that what the manufacturers mean is that it must absolutely never exceed 25mA (or about 200mA combined for all ports) - but it is taken by users to mean that it is automatically current limited so that you do not need resistors - which is wrong.

As I see it, the only way that you can get away with exceeding the 25mA limit is to use multiplexing to reduce the average port current, which is ok as long as your multiplex software does not latch-up due to some software error.

**3v0** · 14th February 2007, 11:30 PM

In regards to the Mondo SuperProbe not using limiting resistors. The author points out that SuperProbe is a study in doing the most with the fewest parts. Possibly because it had to fit in an existing probe case.

Quote:

The Superprobe project was designed to see how much could be done with a PIC chip and just a few parts.

If you have the room use limiting resistors.

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13th February 2007, 03:37 PM	(permalink)
pasanrobotics	Very Simple LED Clock Using 16F84A or 16F628A Its working perfectly. Go here for more Details

14th February 2007, 02:06 AM	(permalink)
Gayan Soyza	Nice fully compact design.All with familliar parts. PORTA drivng the common of the segments directly???????and the rows also same.It can cause load more current through the PIC pin even when its in multiplexing mode. Thankx for sharing..... __________________ Gayan My Website http://gsmicro.blogspot.com/ Last edited by Gayan Soyza; 14th February 2007 at 02:25 AM.

14th February 2007, 02:15 AM	(permalink)
blueroomelectronics	It is possible with some fancy programming to light only one segment at a time. It's done here with the super probe. http://members.cox.net/berniekm/super.html __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

14th February 2007, 10:32 PM	(permalink)
bananasiong	Is there any different of connecting the 7-segment display directly to the output port without any current limiting resistor as compared to drive the 7-segment display with transistor plus current limiting resistor? Since the output current of the PIC's is only 25 mA, it won't burn the LED right? __________________ Superman returns..