The oscilloscope I am using
Having an oscilloscope makes tinkering with electronics much easier. You can see what is actually happening on the wire.
For example, without an oscilloscope, I wouldn't have gotten my OV7670 camera library working. With these kinds of projects where timing is critical, you absolutely need to see the signals.
The Rigol DS1054Z is a relatively low-cost entry-level scope. You get a lot of bang for your buck. It has a lot of internal memory to record a signal that you can then analyze.
A good review of Rigol DS1054Z by EEVblog:
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