pic based 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 r
pic based oscilloscope clock - schematic

ight 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. 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.

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