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When I connect my oscilloscope probes to my SPI lines, the line voltages get affected a lot and so my SPI comms fail.
I am using a breadboard as an intermediary between the two devices and adding cables to the breadboard to scope from.
Is there a better way to probe SPI? I'm currently looking to snip my wires to expose the metal and probe that way to reduce the length of the SPI connections.
Any better ideas would be appreciated.
Running SPI at 10 MHz
Your problem isn't so much the scope probes as the breadboard.
The breadboard adds series inductance (as though you had installed coils in series with the SPI signals) and parallel capacitance (as though you had put small capacitors from the SPI signals to ground.) This will slow the rising and falling edges, making it more difficult to detect level changes. The inductance can also cause ringing - there can be false level transitions from the ringing.
Attach your probes directly to the SPI signals, right at the point where the wires connect to one of your boards.
Use 10X probes if you have them - they are less of a load on the signal lines.
SPI uses relatively fast signals, and isn't intended to be used between circuit boards.
It is intended for use on a single board with short connections.
The wires between the boards are probably making your SPI signals "unhappy," never mind the breadboard and the additional load of the oscilloscope.
Put the breadboard down and back away slowly. Nobody has to be injured here.
The thing to look out for is the parasitic capacitance you create on the communication lines.
Also how is your oscilloscope grounded ? Make sure you clip the ground probe somewhere. If your device under test is floating, you can't rely on the earth reference.
While other answers are fairly correct, in my experience the big problem with breadboards, especially the cheap ones, is that as soon as you use wires of different sizes, it spreads apart the breadboard spring plates and causes bad contacting.
My guess is when you insert your scope wire into the breadboard, this is exactly what happens. Try to probe a different way, use a higher quality breadboard, or solder your circuit on a test PCB (they are cheap these days).
Personally, I mostly stopped working with breadboard altogether because of these issues, and as the cost of PCBs has become so low that you can just make a PCB for 5$, and there are fewer and fewer DIP components.
