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Topic: voltage drop (Read 1 time) previous topic - next topic


Op's drawing, rotated, cropped, resized and isolated:

What, I need to say something else too?


Jun 14, 2018, 03:26 pm Last Edit: Jun 14, 2018, 03:27 pm by TomGeorge
You need to connect your modules in a star configuration to make sure the display gets sufficient supply current.

Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....


The problem with the erratic response is probably due to signal degradation - as the clock and data
signals move from unit to unit there will be degradation particularly of the clock signal - fast logic signals are
not designed to travel more than a foot or so without some sort of conditioning either at sending end
or receiving end or both.

I would suggest adding 100 ohms in series with the clock signal at receiving end of every cable run, and
using a lower data rate.  If the cable runs are more than a few metres you really need to use a physical
signalling method designed for distance, such as RS485.

Regenerating the clock signal at each stage with a buffer is a very good idea - the data already gets
regenerated by the shift register.
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