PIC Oscilloscope Clock

For those are not into electronics, you must know that an oscilloscope has basically only one timebase to move the spot horizontally from left to right with the same intensity. The vertical deviation is function to the input voltage. You understand immediately that you can't directly display 7 segment digits, because you can't move the spot from right to left.



By using X/Y mode, where the spot is controlled on two axes by two different voltages, it is possible to draw a picture (as in the examples mentioned above), but a fast digital to analog converter with two channels and at least 8 bits of resolution would be needed.

So we have to deal with a spot that always goes from left to right in the same period of time.
If we want to have a 7segment-like display, we have to draw :

vertical segments : easy to do, just change voltage up and down quickly a few times.
horizontal segments : easy to do, just set a voltage level and keep it as long as you need.

By using 2 PIC outputs and a basic R2R digital to analog converter, we can have up to four different voltage levels : 3 for the vertical segment, and another one where to put the spot when it is not in use to draw a segment.

But the problem is that a 7 segment digit may have up to 3 horizontal lines at a time (like 2, 3, 8, 9..) but we can draw only one during one spot deviation.
So we will have to cheat with retinal persistence and use multiple frames : since we can have only one vertical segment per period, three periods will be needed to draw a full 7 segment digit.

Supposing we want to display 12:34:56 on the screen :

During the first period, we will draw all vertical segments, and horizontal upper segments only :

As a game, I let you try to find out the spot trajectory.
Don't forget the rules :

you can't go backward
you can't clear the spot

But you can move so fast vertically that the eye can't see the spot moving.

The lowest line under the digits is not significant, it his the place where the spot is parked when not used to draw a segment.

Schematic Diagram:






Working Video



for more details see this LINK
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ExperimenterUK
Mon Dec 03 2018, 05:17 PM
Please post questions in the forum. The chat box is for chat
Mon Dec 03 2018, 06:43 AM
help!me!
help! I don't understand busy flag!
Sun Dec 02 2018, 08:01 PM
ile
hello
Mon Nov 12 2018, 05:58 AM
Pavan_user
i have seen your replica of I2C programming using AT89C51 but i am unable to understand the "ack_bit" variable usage ...looks like it is always 1...can you elaborate how acknowledgment is working....
bgk3678
Tue Nov 06 2018, 02:36 PM
kindly any one give solution for my problem
ExperimenterUK
Mon Nov 05 2018, 09:48 PM
Pins high is the normal state. You need a program to set them low
mayengbam
Sun Nov 04 2018, 05:41 PM
hello, i am niranjoy, alll the port of my 8051 is always high, even i erase all the program. why is it so happen and what is the problem. any one please help me!
Sun Nov 04 2018, 02:16 PM
BASAVARAJ g kudamble
hi I am interfacing GSM 300 to 8051 microcontroller to receive message from mobile
ExperimenterUK
Sat Sep 29 2018, 06:28 PM
Please post questions in the forum.
Sat Sep 29 2018, 11:26 AM
Ashfaq Ch
hi i have some AT89C51RC microcontrollers already programed. some one help us to how to download from AT89C51RC and after study and edit all corractions reload to AT89C51RC controller

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